preprocess_targetlist thought PHVs couldn't appear here.
It was mistaken, as per report from Önder Kalacı.
Surveying other pull_var_clause calls, I noted no similar errors,
but I did notice that qual_is_pushdown_safe's assertion about
!contain_window_function was pointless, because the following
pull_var_clause call would complain about them anyway. In HEAD
only, remove the redundant Assert and improve the commentary.
Discussion: https://postgr.es/m/CACawEhUuum-gC_2S3sXLTcsk7bUSPSHOD+g1ZpfKaDK-KKPPWA@mail.gmail.com
adjust_appendrel_attrs can't transfer nullingrel labeling to a non-Var
translation expression (mainly because it's too late to wrap such an
expression in a PlaceHolderVar). I'd supposed in commit 2489d76c4
that that restriction was unreachable because we'd not attempt to push
problematic clauses down to an appendrel child relation. I forgot that
set_append_rel_size blindly converts all the parent rel's joininfo
clauses to child clauses, and that list could well contain clauses
from above a nulling outer join.
We might eventually have to devise a direct fix for this implementation
restriction, but for now it seems enough to filter out troublesome
clauses while constructing the child's joininfo list. Such clauses
are certainly not useful while constructing paths for the child rel;
they'll have to be applied later when we join the completed appendrel
to something else. So we don't need them here, and omitting them from
the list should save a few cycles while processing the child rel.
Per bug #17832 from Marko Tiikkaja.
Discussion: https://postgr.es/m/17832-d0a8106cdf1b722e@postgresql.org
This function has been semi-deprecated ever since we invented
bms_next_member(). Its habit of scribbling on the input bitmapset
isn't great, plus for sufficiently large bitmapsets it would take
O(N^2) time to complete a loop. Now we have the additional problem
that reducing the input to empty while leaving it still accessible
would violate a planned invariant. So let's just get rid of it,
after updating the few extant callers to use bms_next_member().
Patch by me; thanks to Nathan Bossart and Richard Guo for review.
Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
It's possible, in admittedly-rather-contrived cases, for an eclass
to generate a derived "join" qual that constrains the post-outer-join
value(s) of some RHS variable(s) without mentioning the LHS at all.
While the mechanisms were set up to work for this, we fell foul of
the "get_common_eclass_indexes" filter installed by commit 3373c7155:
it could decide that such an eclass wasn't relevant to the join, so
that the required qual clause wouldn't get emitted there or anywhere
else.
To fix, apply get_common_eclass_indexes only at inner joins, where
its rule is still valid. At an outer join, fall back to examining all
eclasses that mention either input (or the OJ relid, though it should
be impossible for an eclass to mention that without mentioning either
input). Perhaps we can improve on that later, but the cost/benefit of
adding more complexity to skip some irrelevant eclasses is dubious.
To allow cheaply distinguishing outer from inner joins, pass the
ojrelid to generate_join_implied_equalities as a separate argument.
This also allows cleaning up some sloppiness that had crept into
the definition of its join_relids argument, and it allows accurate
calculation of nominal_join_relids for a child outer join. (The
latter oversight seems not to have been a live bug, but it certainly
could have caused problems in future.)
Also fix what might be a live bug in check_index_predicates: it was
being sloppy about what it passed to generate_join_implied_equalities.
Per report from Richard Guo.
Discussion: https://postgr.es/m/CAMbWs4-DsTBfOvXuw64GdFss2=M5cwtEhY=0DCS7t2gT7P6hSA@mail.gmail.com
initsplan.c figured that it could push Var-free qual clauses to
the top of the current JoinDomain, which is okay in the abstract.
But if the current domain is inside some outer join, and we later
commute an inside-the-domain outer join with one outside it,
we end up placing the pushed-up qual clause incorrectly.
In distribute_qual_to_rels, avoid this by using the syntactic scope
of the qual clause; with the exception that if we're in the top-level
join domain we can still use the full query relid set, ensuring the
resulting gating Result node goes to the top of the plan. (This is
approximately as smart as the pre-v16 code was. Perhaps we can do
better later, but it's not clear that such cases are worth a lot of
sweat.)
In process_implied_equality, we don't have a clear notion of syntactic
scope, but we do have the results of SpecialJoinInfo construction.
Thumb through those and remove any lower outer joins that might get
commuted to above the join domain. Again, we can make an exception
for the top-level join domain. It'd be possible to work harder here
(for example, by keeping outer joins that aren't shown as potentially
commutable), but I'm going to stop here for the moment. This issue
has convinced me that the current representation of join domains
probably needs further refinement, so I'm disinclined to write
inessential dependent logic just yet.
In passing, tighten the qualscope passed to process_implied_equality
by generate_base_implied_equalities_no_const; there's no need for
it to be larger than the rel we are currently considering.
Tom Lane and Richard Guo, per report from Tender Wang.
Discussion: https://postgr.es/m/CAHewXNk9eJ35ru5xATWioTV4+xZPHptjy9etdcNPjUfY9RQ+uQ@mail.gmail.com
This was not something that required consideration before MERGE
was invented; but MERGE builds a join tree that left-joins to the
result relation, meaning that remove_useless_joins will consider
removing it. That should generally be stopped by the query's use
of output variables from the result relation. However, if the
result relation is inherited (e.g. a partitioned table) then
we don't add any row identity variables to the query until
expand_inherited_rtentry, which happens after join removal.
This was exposed as of commit 3c569049b, which made it possible
to deduce that a partitioned table could contain at most one row
matching a join key, enabling removal of the not-yet-expanded
result relation. Ooops.
To fix, let's just teach join_is_removable that the query result
rel is never removable. It's a cheap enough test in any case,
and it'll save some cycles that we'd otherwise expend in proving
that it's not removable, even in the cases we got right.
Back-patch to v15 where MERGE was added. Although I think the
case cannot be reached in v15, this seems like cheap insurance.
Per investigation of a report from Alexander Lakhin.
Discussion: https://postgr.es/m/36bee393-b351-16ac-93b2-d46d83637e45@gmail.com
For no clearly good reason, make_modifytable assumed that it
could not reach its get-the-FDW-info-the-hard-way path in MERGE.
It's currently possible to demonstrate that assertion failing,
which seems to be due to an upstream planner bug; but there's no
good reason to do it like this at all. Let's apply the principle
of separation of concerns and make the MERGE check separately,
after getting or not getting the fdwroutine pointer.
Per report from Alexander Lakhin. No test case, since I think
the potential test condition will go away soon.
Discussion: https://postgr.es/m/36bee393-b351-16ac-93b2-d46d83637e45@gmail.com
The RelOptInfo->userid field (the user ID to check permissions as) of an
"otherrel" relation was being copied from its parent relation, which is
correct in most cases but wrong when the parent is a subquery. In that
case, using the value from the RTEPermissionInfo of the child itself is
the appropriate thing to do.
Coming up with a test case where user-visible behavior changes proves
hard enough, so we don't add one here.
Bug introduced by a61b1f7482, discovered by Amit while reviewing
nearby code.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqE0WY_AhLnGtTsY7eYebG212XWbM-D8gr2A_ToOHyCywQ@mail.gmail.com
In generate_orderedappend_paths(), when match_partition_order_desc was
true, we would lcons() items to various lists in a loop over each live
partition. When the number of live partitions was large, the lcons()
could show up in profiles due to it having to perform memmove() to make
way for the new list item.
Here we adjust things so that we just perform the loop over the live
partitions backwards when match_partition_order_desc is true. This allows
us to simplify the logic in the loop. Now, as far as the guts of the loop
knows, there's no difference between match_partition_order and
match_partition_order_desc. We can just set match_partition_order to true
so that we build the correct list of paths for the asc and desc case. Per
idea from Andres Freund.
Discussion: https://postgr.es/m/20230217002351.nyt4y5tdzg6hugdt@awork3.anarazel.de
force_parallel_mode is meant to be used to allow us to exercise the
parallel query infrastructure to ensure that it's working as we expect.
It seems some users think this GUC is for forcing the query planner into
picking a parallel plan regardless of the costs. A quick look at the
documentation would have made them realize that they were wrong, but the
GUC is likely too conveniently named which, evidently, seems to often
result in users expecting that it forces the planner into usefully
parallelizing queries.
Here we rename the GUC to something which casual users are less likely to
mistakenly think is what they need to make their query run more quickly.
For now, the old name can still be used. We'll revisit if the old name
mapping can be removed once the buildfarm configs are all updated.
Reviewed-by: John Naylor
Discussion: https://postgr.es/m/CAApHDvrsOi92_uA7PEaHZMH-S4Xv+MGhQWA+GrP8b1kjpS1HjQ@mail.gmail.com
In commit b78f6264e I opined that it was "too risky" to delete a
relation's RelOptInfo from the planner's data structures when we have
realized that we don't need to join to it; so instead we just marked
it as a dead relation. In hindsight that judgment seems flawed: any
subsequent access to such a dead relation is arguably a bug in
itself, so leaving the RelOptInfo present just helps to mask bugs.
Let's delete it instead, allowing removal of the whole notion of a
"dead relation". So far as the regression tests can find, this
requires no other code changes, except for one Assert in equivclass.c
that was very dubiously not complaining about access to a dead rel.
Discussion: https://postgr.es/m/229905.1676062220@sss.pgh.pa.us
Late in the development of commit 2489d76c4, I (tgl) incorrectly
concluded that the new function have_unsafe_outer_join_ref couldn't
ever reach its inner loop. That should be the case if the inner
rel's parameterization is based on just one Var, but it could be
based on Vars from several relations, and then not only is the
inner loop reachable but it's wrongly coded.
Despite those errors, it still appears that the whole thing is
redundant given previous join_is_legal checks, so let's arrange
to only run it in assert-enabled builds.
Diagnosis and patch by Richard Guo, per fuzz testing by Justin Pryzby.
Discussion: https://postgr.es/m/20230212235823.GW1653@telsasoft.com
analyzejoins.c took care to clean out removed relids from the
clause_relids and required_relids of RestrictInfos associated with
the doomed rel ... but it paid no attention to the fact that if such a
RestrictInfo contains an OR clause, there will be sub-RestrictInfos
containing similar fields.
I'm more than a bit surprised that this oversight hasn't caused
visible problems before. In any case, it's certainly broken now,
so add logic to clean out the sub-RestrictInfos recursively.
We might need to back-patch this someday.
Per bug #17786 from Robins Tharakan.
Discussion: https://postgr.es/m/17786-f1ea7fbdab97daec@postgresql.org
One of the add_nulling_relids calls in deconstruct_distribute_oj_quals
added an OJ relid to too few Vars, while the other added it to too
many. We should consider the syntactic structure not
min_left/righthand while deciding which Vars to decorate, and when
considering pushing up a lower outer join pursuant to transforming the
second form of OJ identity 3 to the first form, we only want to
decorate Vars coming from its LHS.
In a related bug, I realized that make_outerjoininfo was failing to
check a very basic property that's needed to apply OJ identity 3:
the syntactically-upper outer join clause can't refer to the lower
join's LHS. This didn't break the join order restriction logic,
but it led to setting bogus commute_xxx bits, possibly resulting
in bogus nullingrel markings in modified quals.
Richard Guo and Tom Lane
Discussion: https://postgr.es/m/CAMbWs497CmBruMx1SOjepWEz+T5NWa4scqbdE9v7ZzSXqH_gQw@mail.gmail.com
Discussion: https://postgr.es/m/CAEP4nAx9C5gXNBfEA0JBfz7B+5f1Bawt-RWQWyhev-wdps8BZA@mail.gmail.com
The code I added in fee7b77b9 could misbehave if commute_above_r
contains multiple relids. While adding too many relids here is
probably harmless (pre-fee7b77b9, we did it all the time), it's
not very expensive to be accurate: we just have to intersect
commute_above_r with the join's relids.
Discussion: https://postgr.es/m/17781-c0405c8b3cd5e072@postgresql.org
The logic for when to add the current outer join's own relid
to the nullingrels sets of output Vars and PHVs was overly
complicated and underly correct. Not sure why I didn't think
of this before, but since what we want is marking per the
syntactic structure, we can just consult our records about
the syntactic structure, ie syn_righthand/syn_lefthand.
Also, tighten the rule about when to add the commute_above_r
bits, in hopes of eliminating some squishy reasoning. I do not
know of a reason to think that that's broken as-is, but this way
seems better.
Per bug #17781 from Robins Tharakan.
Discussion: https://postgr.es/m/17781-c0405c8b3cd5e072@postgresql.org
The portion of join_is_removable() that checks PlaceHolderVars
can be made a little more accurate and intelligible than it was.
The key point is that we can allow join removal even if a PHV
mentions the target rel in ph_eval_at, if that mention was only
added as a consequence of forcing the PHV up to a join level
that's at/above the outer join we're trying to get rid of.
We can check that by testing for the OJ's relid appearing in
ph_eval_at, indicating that it's supposed to be evaluated after
the outer join, plus the existing test that the contained
expression doesn't actually mention the target rel.
While here, add an explicit check that there'll be something left
in ph_eval_at after we remove the target rel and OJ relid. There
is an Assert later on about that, and I'm not too sure that the
case could happen for a PHV satisfying the other constraints,
but let's just check. (There was previously a bms_is_subset test
that meant to cover this risk, but it's broken now because it
doesn't account for the fact that we'll also remove the OJ relid.)
The real reason for revisiting this code though is that the
Assert I left behind in 8538519db turns out to be easily
reachable, because if a PHV of this sort appears in an upper-level
qual clause then that clause's clause_relids will include the
PHV's ph_eval_at relids. This is a mirage though: we have or soon
will remove these relids from the PHV's ph_eval_at, and therefore
they no longer belong in qual clauses' clause_relids either.
Remove that Assert in join_is_removable, and replace the similar
one in remove_rel_from_query with code to remove the deleted relids
from clause_relids.
Per bug #17773 from Robins Tharakan.
Discussion: https://postgr.es/m/17773-a592e6cedbc7bac5@postgresql.org
make_outerjoininfo was set up to update SpecialJoinInfo's
commute_below, commute_above_l, commute_above_r fields as soon as
it found a pair of outer joins that look like they can commute.
However, this decision could be negated later in the same loop due
to finding an intermediate outer join that prevents commutation.
That left us with commute_xxx fields that were contradictory to the
join order restrictions expressed in min_lefthand/min_righthand.
The latter fields would keep us from actually choosing a bad join
order; but the inconsistent commute_xxx fields could bollix details
such as the varnullingrels values created for intermediate join
relation targetlists, ending in an assertion failure in setrefs.c.
To fix, wait till the end of make_outerjoininfo where we have
accurate values for min_lefthand/min_righthand, and then insert
only relids not present in those sets into the commute_xxx fields.
Per SQLSmith testing by Robins Tharakan. Note that while Robins
bisected the failure to commit b448f1c8d, it's really the fault of
2489d76c4. The outerjoin_delayed logic removed in the later commit
was keeping us from deciding that troublesome join pairs commute,
at least in the specific example seen here.
Discussion: https://postgr.es/m/CAEP4nAyAORgE8K_RHSmvWbE9UaChhjbEL1RrDU3neePwwRUB=A@mail.gmail.com
deconstruct_distribute tweaks the outer join scope (ojscope)
it passes to distribute_qual_to_rels when considering an outer
join qual that's above potentially-commutable outer joins.
However, if the current join is *not* potentially commutable,
we shouldn't do that. The argument that distribute_qual_to_rels
will not do something wrong with the bogus ojscope falls flat
if we don't pass it non-null postponed_oj_qual_list. Moreover,
there's no need to play games in this case since we aren't going
to commute anything.
Per SQLSmith testing by Robins Tharakan.
Discussion: https://postgr.es/m/CAEP4nAw74k4b-=93gmfCNX3MOY3y4uPxqbk_MnCVEpdsqHJVsg@mail.gmail.com
If we have a RestrictInfo that mentions both the removal-candidate
relation and the outer join's relid, then that is a pushed-down
condition not a join condition, so it should be grounds for deciding
that we can't remove the outer join. In commit 2489d76c4, I'd blindly
included the OJ's relid into "joinrelids" as per the new standard
convention, but the checks of attr_needed and ph_needed should only
allow the join's input rels to be mentioned.
Having done that, the check for references in pushed-down quals
a few lines further down should be redundant. I left it in place
as an Assert, though.
While researching this I happened across a couple of comments that
worried about the effects of update_placeholder_eval_levels.
That's gone as of b448f1c8d, so we can remove some worry.
Per bug #17769 from Robins Tharakan. The submitted test case
triggers this more or less accidentally because we flatten out
a LATERAL sub-select after we've done join strength reduction;
if we did that in the other order, this problem would be masked
because the outer join would get simplified to an inner join.
To ensure that the committed test case will continue to test
what it means to even if we make that happen someday, use a
test clause involving COALESCE(), which will prevent us from
using it to do join strength reduction.
Patch by me, but thanks to Richard Guo for initial investigation.
Discussion: https://postgr.es/m/17769-e4f7a5c9d84a80a7@postgresql.org
After pulling up LATERAL subqueries, we may have qual clauses that
refer to relations outside their syntactic scope. Before doing any
such pullup, prepjointree.c checks to make sure that it wouldn't
create a semantically-invalid situation; but we leave it to
deconstruct_jointree() to actually move these quals up the join
tree to a place where they can be evaluated. In commit 2489d76c4,
I (tgl) refactored deconstruct_jointree() in a way that caused
assertion failures while moving such quals, because the new logic
failed to distinguish "this jointree node is a parent of the source
one" from "this jointree node is processed after the source
one in depth-first order".
Fix this, and at the same time reduce the overhead a bit, by
getting rid of the common PostponedQual list and instead making each
JoinTreeItem contain a list of quals that needed to be postponed to
its level. We can help distribute_qual_to_rels find the appropriate
JoinTreeItem efficiently by adding parent-item links to the
JoinTreeItem data structure. This ends up being the same number
of relid subset checks as the original (pre-bug) logic, but less
list manipulation is required during multi-level postponements.
Richard Guo and Tom Lane, per bug #17768 from Robins Tharakan.
Discussion: https://postgr.es/m/17768-5ac8730ece54478f@postgresql.org
Here remove some dead code from heapgettup() and heapgettup_pagemode()
which was trying to support NoMovementScanDirection scans. This code can
never be reached as standard_ExecutorRun() never calls ExecutePlan with
NoMovementScanDirection.
Additionally, plans which were scanning an unordered index would use
NoMovementScanDirection rather than ForwardScanDirection. There was no
real need for this, so here we adjust this so we use ForwardScanDirection
for unordered index scans. A comment in pathnodes.h claimed that
NoMovementScanDirection was used for PathKey reasons, but if that was
true, it no longer is, per code in build_index_paths().
This does change the non-text format of the EXPLAIN output so that
unordered index scans now have a "Forward" scan direction rather than
"NoMovement". The text format of EXPLAIN has not changed.
Author: Melanie Plageman
Reviewed-by: Tom Lane, David Rowley
Discussion: https://postgr.es/m/CAAKRu_bvkhka0CZQun28KTqhuUh5ZqY=_T8QEqZqOL02rpi2bw@mail.gmail.com
In commit 2489d76c4, I'd thought it'd be safe to assert that a
PlaceHolderVar appearing in a scan-level expression has empty
nullingrels. However this is not so, as when we determine that a
join relation is certainly empty we'll put its targetlist into a
Result-with-constant-false-qual node, and nothing is done to adjust
the nullingrels of the Vars or PHVs therein. (Arguably, a Result
used in this way isn't really a scan-level node, but it certainly
isn't an upper node either ...)
It's not clear this is worth any close analysis, so let's just
take out the faulty Assert.
Per report from Robins Tharakan. I added a test case based on
his example, just in case somebody tries to tighten this up.
Discussion: https://postgr.es/m/CAEP4nAz7Enq3+DEthGG7j27DpuwSRZnW0Nh6jtNh75yErQ_nbA@mail.gmail.com
EquivalenceClasses are now understood as applying within a "join
domain", which is a set of inner-joined relations (possibly underneath
an outer join). We no longer need to treat an EC from below an outer
join as a second-class citizen.
I have hopes of eventually being able to treat outer-join clauses via
EquivalenceClasses, by means of only applying deductions within the
EC's join domain. There are still problems in the way of that, though,
so for now the reconsider_outer_join_clause logic is still here.
I haven't been able to get rid of RestrictInfo.is_pushed_down either,
but I wonder if that could be recast using JoinDomains.
I had to hack one test case in postgres_fdw.sql to make it still test
what it was meant to, because postgres_fdw is inconsistent about
how it deals with quals containing non-shippable expressions; see
https://postgr.es/m/1691374.1671659838@sss.pgh.pa.us. That should
be improved, but I don't think it's within the scope of this patch
series.
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
Remove RestrictInfo.nullable_relids, along with a good deal of
infrastructure that calculated it. One use-case for it was in
join_clause_is_movable_to, but we can now replace that usage with
a check to see if the clause's relids include any outer join
that can null the target relation. The other use-case was in
join_clause_is_movable_into, but that test can just be dropped
entirely now that the clause's relids include outer joins.
Furthermore, join_clause_is_movable_into should now be
accurate enough that it will accept anything returned by
generate_join_implied_equalities, so we can restore the Assert
that was diked out in commit 95f4e59c3.
Remove the outerjoin_delayed mechanism. We needed this before to
prevent quals from getting evaluated below outer joins that should
null some of their vars. Now that we consider varnullingrels while
placing quals, that's taken care of automatically, so throw the
whole thing away.
Teach remove_useless_result_rtes to also remove useless FromExprs.
Having done that, the delay_upper_joins flag serves no purpose any
more and we can remove it, largely reverting 11086f2f2.
Use constant TRUE for "dummy" clauses when throwing back outer joins.
This improves on a hack I introduced in commit 6a6522529. If we
have a left-join clause l.x = r.y, and a WHERE clause l.x = constant,
we generate r.y = constant and then don't really have a need for the
join clause. But we must throw the join clause back anyway after
marking it redundant, so that the join search heuristics won't think
this is a clauseless join and avoid it. That was a kluge introduced
under time pressure, and after looking at it I thought of a better
way: let's just introduce constant-TRUE "join clauses" instead,
and get rid of them at the end. This improves the generated plans for
such cases by not having to test a redundant join clause. We can also
get rid of the ugly hack used to mark such clauses as redundant for
selectivity estimation.
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
Traditionally we used the same Var struct to represent the value
of a table column everywhere in parse and plan trees. This choice
predates our support for SQL outer joins, and it's really a pretty
bad idea with outer joins, because the Var's value can depend on
where it is in the tree: it might go to NULL above an outer join.
So expression nodes that are equal() per equalfuncs.c might not
represent the same value, which is a huge correctness hazard for
the planner.
To improve this, decorate Var nodes with a bitmapset showing
which outer joins (identified by RTE indexes) may have nulled
them at the point in the parse tree where the Var appears.
This allows us to trust that equal() Vars represent the same value.
A certain amount of klugery is still needed to cope with cases
where we re-order two outer joins, but it's possible to make it
work without sacrificing that core principle. PlaceHolderVars
receive similar decoration for the same reason.
In the planner, we include these outer join bitmapsets into the relids
that an expression is considered to depend on, and in consequence also
add outer-join relids to the relids of join RelOptInfos. This allows
us to correctly perceive whether an expression can be calculated above
or below a particular outer join.
This change affects FDWs that want to plan foreign joins. They *must*
follow suit when labeling foreign joins in order to match with the
core planner, but for many purposes (if postgres_fdw is any guide)
they'd prefer to consider only base relations within the join.
To support both requirements, redefine ForeignScan.fs_relids as
base+OJ relids, and add a new field fs_base_relids that's set up by
the core planner.
Large though it is, this commit just does the minimum necessary to
install the new mechanisms and get check-world passing again.
Follow-up patches will perform some cleanup. (The README additions
and comments mention some stuff that will appear in the follow-up.)
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
This adds combine, serial and deserial functions for the array_agg() and
string_agg() aggregate functions, thus allowing these aggregates to
partake in partial aggregations. This allows both parallel aggregation to
take place when these aggregates are present and also allows additional
partition-wise aggregation plan shapes to include plans that require
additional aggregation once the partially aggregated results from the
partitions have been combined.
Author: David Rowley
Reviewed-by: Andres Freund, Tomas Vondra, Stephen Frost, Tom Lane
Discussion: https://postgr.es/m/CAKJS1f9sx_6GTcvd6TMuZnNtCh0VhBzhX6FZqw17TgVFH-ga_A@mail.gmail.com
RelOptInfo.userid is the same for all relations in a given inheritance
tree, so the code in examine_variable() and example_simple_variable()
that repeats the ACL checks on the root parent rel instead of a given
leaf child relations need not recompute userid too.
Author: Amit Langote <amitlangote09@gmail.com>
Reported-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20221210201753.GA27893@telsasoft.com
The rule system needs "old" and/or "new" pseudo-RTEs in rule actions
that are ON INSERT/UPDATE/DELETE. Historically it's put such entries
into the ON SELECT rules of views as well, but those are really quite
vestigial. The only thing we've used them for is to carry the
view's relid forward to AcquireExecutorLocks (so that we can
re-lock the view to verify it hasn't changed before re-using a plan)
and to carry its relid and permissions data forward to execution-time
permissions checks. What we can do instead of that is to retain
these fields of the RTE_RELATION RTE for the view even after we
convert it to an RTE_SUBQUERY RTE. This requires a tiny amount of
extra complication in the planner and AcquireExecutorLocks, but on
the other hand we can get rid of the logic that moves that data from
one place to another.
The principal immediate benefit of doing this, aside from a small
saving in the pg_rewrite data for views, is that these pseudo-RTEs
no longer trigger ruleutils.c's heuristic about qualifying variable
names when the rangetable's length is more than 1. That results
in quite a number of small simplifications in regression test outputs,
which are all to the good IMO.
Bump catversion because we need to dump a few more fields of
RTE_SUBQUERY RTEs. While those will always be zeroes anyway in
stored rules (because we'd never populate them until query rewrite)
they are useful for debugging, and it seems like we'd better make
sure to transmit such RTEs accurately in plans sent to parallel
workers. I don't think the executor actually examines these fields
after startup, but someday it might.
This is a second attempt at committing 1b4d280ea. The difference
from the first time is that now we can add some filtering rules to
AdjustUpgrade.pm to allow cross-version upgrade testing to pass
despite all the cosmetic changes in CREATE VIEW outputs.
Amit Langote (filtering rules by me)
Discussion: https://postgr.es/m/CA+HiwqEf7gPN4Hn+LoZ4tP2q_Qt7n3vw7-6fJKOf92tSEnX6Gg@mail.gmail.com
Discussion: https://postgr.es/m/891521.1673657296@sss.pgh.pa.us
Avoid explicitly grouping by columns that we know are redundant
for sorting, for example we need group by only one of x and y in
SELECT ... WHERE x = y GROUP BY x, y
This comes up more often than you might think, as shown by the
changes in the regression tests. It's nearly free to detect too,
since we are just piggybacking on the existing logic that detects
redundant pathkeys. (In some of the existing plans that change,
it's visible that a sort step preceding the grouping step already
didn't bother to sort by the redundant column, making the old plan
a bit silly-looking.)
To do this, build processed_groupClause and processed_distinctClause
lists that omit any provably-redundant sort items, and consult those
not the originals where relevant. This means that within the
planner, one should usually consult root->processed_groupClause or
root->processed_distinctClause if one wants to know which columns
are to be grouped on; but to check whether grouping or distinct-ing
is happening at all, check non-NIL-ness of parse->groupClause or
parse->distinctClause. This is comparable to longstanding rules
about handling the HAVING clause, so I don't think it'll be a huge
maintenance problem.
nodeAgg.c also needs minor mods, because it's now possible to generate
AGG_PLAIN and AGG_SORTED Agg nodes with zero grouping columns.
Patch by me; thanks to Richard Guo and David Rowley for review.
Discussion: https://postgr.es/m/185315.1672179489@sss.pgh.pa.us
In 1349d2790, we gave the planner the ability to provide ORDER BY/DISTINCT
Aggrefs with presorted input so that nodeAgg would not have to perform
sorts during execution. That commit failed to properly consider the
implications of if the Aggref had a volatile function in its ORDER
BY/DISTINCT clause. As it happened, this resulted in an ERROR about the
volatile function being missing from the targetlist.
Here, instead of adding the volatile function to the targetlist, we just
never consider an Aggref with a volatile function in its ORDER BY/DISTINCT
clause when choosing which Aggrefs we should sort by. We do this as if we
were to choose a plan which provided these aggregates with presorted
input, then if there were many such aggregates which could all share the
same sort order, then it may be surprising if they all shared the same
sort sometimes and didn't at other times when some other set of aggregates
were given presorted results. We can avoid this inconsistency by just
never providing these volatile function aggregates with presorted input.
Reported-by: Dean Rasheed
Discussion: https://postgr.es/m/CAEZATCWETioXs5kY8vT6BVguY41_wD962VDk=u_Nvd7S1UXzuQ@mail.gmail.com
This reverts commit 1b4d280ea1.
It's broken the buildfarm members that run cross-version-upgrade tests,
because they're not prepared to deal with cosmetic differences between
CREATE VIEW commands emitted by older servers and HEAD. Even if we had
a solution to that, which we don't, it'd take some time to roll it out
to the affected animals. This improvement isn't valuable enough to
justify addressing that problem on an emergency basis, so revert it
for now.
The rule system needs "old" and/or "new" pseudo-RTEs in rule actions
that are ON INSERT/UPDATE/DELETE. Historically it's put such entries
into the ON SELECT rules of views as well, but those are really quite
vestigial. The only thing we've used them for is to carry the
view's relid forward to AcquireExecutorLocks (so that we can
re-lock the view to verify it hasn't changed before re-using a plan)
and to carry its relid and permissions data forward to execution-time
permissions checks. What we can do instead of that is to retain
these fields of the RTE_RELATION RTE for the view even after we
convert it to an RTE_SUBQUERY RTE. This requires a tiny amount of
extra complication in the planner and AcquireExecutorLocks, but on
the other hand we can get rid of the logic that moves that data from
one place to another.
The principal immediate benefit of doing this, aside from a small
saving in the pg_rewrite data for views, is that these pseudo-RTEs
no longer trigger ruleutils.c's heuristic about qualifying variable
names when the rangetable's length is more than 1. That results
in quite a number of small simplifications in regression test outputs,
which are all to the good IMO.
Bump catversion because we need to dump a few more fields of
RTE_SUBQUERY RTEs. While those will always be zeroes anyway in
stored rules (because we'd never populate them until query rewrite)
they are useful for debugging, and it seems like we'd better make
sure to transmit such RTEs accurately in plans sent to parallel
workers. I don't think the executor actually examines these fields
after startup, but someday it might.
Amit Langote
Discussion: https://postgr.es/m/CA+HiwqEf7gPN4Hn+LoZ4tP2q_Qt7n3vw7-6fJKOf92tSEnX6Gg@mail.gmail.com
Prior to this, we only considered a full sort on the cheapest input path
and uniquifying any path which was already sorted in the required sort
order. Here we adjust create_final_distinct_paths() so that it also
adds an Incremental Sort path on any path which has presorted keys.
Additionally, this adjusts the parallel distinct code so that we now
consider sorting the cheapest partial path and incrementally sorting any
partial paths with presorted keys. Previously we didn't consider any
sorting for parallel distinct and only added a unique path atop any path
which had the required pathkeys already.
Author: David Rowley
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/CAApHDvo8Lz2H=42urBbfP65LTcEUOh288MT7DsG2_EWtW1AXHQ@mail.gmail.com
This allows left join removals and unique joins to work with partitioned
tables. The planner just lacked sufficient proofs that a given join
would not cause any row duplication. Unique indexes currently serve as
that proof, so have get_relation_info() populate the indexlist for
partitioned tables too.
Author: Arne Roland
Reviewed-by: Alvaro Herrera, Zhihong Yu, Amit Langote, David Rowley
Discussion: https://postgr.es/m/c3b2408b7a39433b8230bbcd02e9f302@index.de
During the development of 728202b63, which was aimed at reducing the
number of sorts required to evaluate multiple window functions with
different WindowClause definitions, the code written sorted the
WindowClauses in reverse tleSortGroupRef order. There appears to be no
discussion in the thread which was opened to discuss the development of
this patch and no comments mentioning the fact that having the
WindowClauses in reverse tleSortGroupRef order makes it more likely that
the final WindowClause to be evaluated will provide presorted input to
the query's DISTINCT or ORDER BY clause. The reason for this is that the
tleSortGroupRef indexes are assigned for the DISTINCT and ORDER BY clauses
before they are for the WindowClauses PARTITION BY and ORDER BY clauses.
Putting the WindowClause with the lowest tleSortGroupRef last means that
it's more likely that no additional sorting is required for the query's
DISTINCT or ORDER BY clause.
All we're doing here is adding some tests and a comment to help ensure
that remains true and that we don't accidentally forget to consider this
again should we ever rewrite that code.
Author: Ankit Kumar Pandey, David Rowley
Discussion: https://postgr.es/m/CAApHDvq=g2=ny59f1bvwRVvupsgPHK-KjLPBsSL25fVuGZ4idQ@mail.gmail.com
We were identifying the updatable generated columns of inheritance
children by transposing the calculation made for their parent.
However, there's nothing that says a traditional-inheritance child
can't have generated columns that aren't there in its parent, or that
have different dependencies than are in the parent's expression.
(At present it seems that we don't enforce that for partitioning
either, which is likely wrong to some degree or other; but the case
clearly needs to be handled with traditional inheritance.)
Hence, drop the very-klugy-anyway "extraUpdatedCols" RTE field
in favor of identifying which generated columns depend on updated
columns during executor startup. In HEAD we can remove
extraUpdatedCols altogether; in back branches, it's still there but
always empty. Another difference between the HEAD and back-branch
versions of this patch is that in HEAD we can add the new bitmap field
to ResultRelInfo, but that would cause an ABI break in back branches.
Like 4b3e37993, add a List field at the end of struct EState instead.
Back-patch to v13. The bogus calculation is also being made in v12,
but it doesn't have the same visible effect because we don't use it
to decide which generated columns to recalculate; as a consequence of
which the patch doesn't apply easily. I think that there might still
be a demonstrable bug associated with trigger firing conditions, but
that's such a weird corner-case usage that I'm content to leave it
unfixed in v12.
Amit Langote and Tom Lane
Discussion: https://postgr.es/m/CA+HiwqFshLKNvQUd1DgwJ-7tsTp=dwv7KZqXC4j2wYBV1aCDUA@mail.gmail.com
Discussion: https://postgr.es/m/2793383.1672944799@sss.pgh.pa.us
While on it, newlines are removed from the end of two elog() strings.
The others are simple grammar mistakes. One comment in pg_upgrade
referred incorrectly to sequences since a7e5457.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20221230231257.GI1153@telsasoft.com
Backpatch-through: 11
Fix incorrect code which was trying to convert a Bitmapset of columns at
the attnums according to a parent table and transform them into the
equivalent Bitmapset with same attnums according to the given child table.
This code is new as of a61b1f748 and was failing to do the correct
translation when there was an intermediate parent table between 'rel' and
'top_parent_rel'.
Reported-by: Ranier Vilela
Author: Richard Guo, Amit Langote
Discussion: https://postgr.es/m/CAEudQArohfB_Gy%2BhcH2-bANUkxgjJiP%3DABq01_LgTNTbcNijag%40mail.gmail.com
WindowFuncs such as row_number() don't care if it's called with ROWS
UNBOUNDED PRECEDING AND CURRENT ROW or with RANGE UNBOUNDED PRECEDING AND
CURRENT ROW. The latter is less efficient as the RANGE option requires
that the executor check for peer rows, so using the ROW option instead
would cause less overhead. Because RANGE is part of the default frame
options for WindowClauses, it means WindowAgg is, by default, working much
harder than it needs to for window functions where the ROWS / RANGE option
has no effect on the window function's result.
On a test query from the discussion thread, a performance improvement of
344% was seen by using ROWS instead of RANGE.
Here we add a new support function node type to allow support functions to
be called for window functions so that the most optimal version of the
frame options can be set. The planner has been adjusted so that the frame
options are changed only if all window functions sharing the same window
clause agree on what the optimized frame options are.
Here we give the ability for row_number(), rank(), dense_rank(),
percent_rank(), cume_dist() and ntile() to alter their WindowClause's
frameOptions.
Reviewed-by: Vik Fearing, Erwin Brandstetter, Zhihong Yu
Discussion: https://postgr.es/m/CAGHENJ7LBBszxS+SkWWFVnBmOT2oVsBhDMB1DFrgerCeYa_DyA@mail.gmail.com
Discussion: https://postgr.es/m/CAApHDvohAKEtTXxq7Pc-ic2dKT8oZfbRKeEJP64M0B6+S88z+A@mail.gmail.com
perform_pullup_replace_vars() knows how to scan the whole parent
query tree when we are replacing Vars during a subquery flattening
operation. However, for the specific case of flattening a
UNION ALL leaf query, that's mostly wasted work: the only place
where relevant Vars could exist is in the AppendRelInfo that we
just made for this leaf. Teaching perform_pullup_replace_vars()
to just deal with that and exit is worthwhile because, if we have
N such subqueries to pull up, we were spending O(N^2) work uselessly
mutating the AppendRelInfos for all the other subqueries.
While we're at it, avoid calling substitute_phv_relids if there are no
PlaceHolderVars, and remove an obsolete check of parse->hasSubLinks.
Andrey Lepikhov and Tom Lane
Discussion: https://postgr.es/m/703c09a2-08f3-d2ec-b33d-dbecd62428b8@postgrespro.ru
Andrey Lepikhov demonstrated a case where we spend an unreasonable
amount of time in pull_up_subqueries(). Not only is that recursing
with no explicit check for stack overrun, but the code seems not
interruptable by control-C. Let's stick a CHECK_FOR_INTERRUPTS
there, along with sprinkling some stack depth checks.
An actual fix for the excessive time consumption seems a bit
risky to back-patch; but this isn't, so let's do so.
Discussion: https://postgr.es/m/703c09a2-08f3-d2ec-b33d-dbecd62428b8@postgrespro.ru
1349d279 added query planner support to allow more efficient execution of
aggregate functions which have an ORDER BY or a DISTINCT clause. Prior to
that commit, the planner would only request that the lower planner produce
a plan with the order required for the GROUP BY clause and it would be
left up to nodeAgg.c to perform the final sort of records within each
group so that the aggregate transition functions were called in the
correct order. Now that the planner requests the lower planner produce a
plan with the GROUP BY and the ORDER BY / DISTINCT aggregates in mind,
there is the possibility that the planner chooses a plan which could be
less efficient than what would have been produced before 1349d279.
While developing 1349d279, I had in mind that Incremental Sort would help
us in cases where an index exists only on the GROUP BY column(s).
Incremental Sort would just replace the implicit tuplesorts which are
being performed in nodeAgg.c. However, because the planner has the
flexibility to instead choose a plan which just performs a full sort on
both the GROUP BY and ORDER BY / DISTINCT aggregate columns, there is
potential for the planner to make a bad choice. The costing for
Incremental Sort is not perfect as it assumes an even distribution of rows
to sort within each sort group.
Here we add an escape hatch in the form of the enable_presorted_aggregate
GUC. This will allow users to get the pre-PG16 behavior in cases where
they have no other means to convince the query planner to produce a plan
which only sorts on the GROUP BY column(s).
Discussion: https://postgr.es/m/CAApHDvr1Sm+g9hbv4REOVuvQKeDWXcKUAhmbK5K+dfun0s9CvA@mail.gmail.com
When incremental sorts were added in v13 a 1.5x pessimism factor was added
to the cost modal. Seemingly this was done because the cost modal only
has an estimate of the total number of input rows and the number of
presorted groups. It assumes that the input rows will be evenly
distributed throughout the presorted groups. The 1.5x pessimism factor
was added to slightly reduce the likelihood of incremental sorts being
used in the hope to avoid performance regressions where an incremental
sort plan was picked and turned out slower due to a large skew in the
number of rows in the presorted groups.
An additional quirk with the path generation code meant that we could
consider both a sort and an incremental sort on paths with presorted keys.
This meant that with the pessimism factor, it was possible that we opted
to perform a sort rather than an incremental sort when the given path had
presorted keys.
Here we remove the 1.5x pessimism factor to allow incremental sorts to
have a fairer chance at being chosen against a full sort.
Previously we would generally create a sort path on the cheapest input
path (if that wasn't sorted already) and incremental sort paths on any
path which had presorted keys. This meant that if the cheapest input path
wasn't completely sorted but happened to have presorted keys, we would
create a full sort path *and* an incremental sort path on that input path.
Here we change this logic so that if there are presorted keys, we only
create an incremental sort path, and create sort paths only when a full
sort is required.
Both the removal of the cost pessimism factor and the changes made to the
path generation make it more likely that incremental sorts will now be
chosen. That, of course, as with teaching the planner any new tricks,
means an increased likelihood that the planner will perform an incremental
sort when it's not the best method. Our standard escape hatch for these
cases is an enable_* GUC. enable_incremental_sort already exists for
this.
This came out of a report by Pavel Luzanov where he mentioned that the
master branch was choosing to perform a Seq Scan -> Sort -> Group
Aggregate for his query with an ORDER BY aggregate function. The v15 plan
for his query performed an Index Scan -> Group Aggregate, of course, the
aggregate performed the final sort internally in nodeAgg.c for the
aggregate's ORDER BY. The ideal plan would have been to use the index,
which provided partially sorted input then use an incremental sort to
provide the aggregate with the sorted input. This was not being chosen
due to the pessimism in the incremental sort cost modal, so here we remove
that and rationalize the path generation so that sort and incremental sort
plans don't have to needlessly compete. We assume that it's senseless
to ever use a full sort on a given input path where an incremental sort
can be performed.
Reported-by: Pavel Luzanov
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/9f61ddbf-2989-1536-b31e-6459370a6baa%40postgrespro.ru
9d9c02ccd added code to allow WindowAgg to take some shortcuts when a
monotonic WindowFunc reached some value that it could never come back
from due to the function's monotonic nature. That commit added a
runCondition field to WindowClause to store the condition which, when it
becomes false we can start taking shortcuts in nodeWindowAgg.c.
Here we fix an issue where subquery pullups didn't properly update the
runCondition to update the Vars to properly reference the new query level.
Here we also add a missing call to preprocess_expression() for the
WindowClause's runCondtion. The WindowFuncs in the targetlist will have
had this process done, so we must also do it for the WindowFuncs in the
runCondition so that they can be correctly found in the targetlist
during setrefs.c
Bug: #17709
Reported-by: Alexey Makhmutov
Author: Richard Guo, David Rowley
Discussion: https://postgr.es/m/17709-4f557160e3e8ee9a@postgresql.org
Backpatch-through: 15, where 9d9c02ccd was introduced
Currently, information about the permissions to be checked on relations
mentioned in a query is stored in their range table entries. So the
executor must scan the entire range table looking for relations that
need to have permissions checked. This can make the permission checking
part of the executor initialization needlessly expensive when many
inheritance children are present in the range range. While the
permissions need not be checked on the individual child relations, the
executor still must visit every range table entry to filter them out.
This commit moves the permission checking information out of the range
table entries into a new plan node called RTEPermissionInfo. Every
top-level (inheritance "root") RTE_RELATION entry in the range table
gets one and a list of those is maintained alongside the range table.
This new list is initialized by the parser when initializing the range
table. The rewriter can add more entries to it as rules/views are
expanded. Finally, the planner combines the lists of the individual
subqueries into one flat list that is passed to the executor for
checking.
To make it quick to find the RTEPermissionInfo entry belonging to a
given relation, RangeTblEntry gets a new Index field 'perminfoindex'
that stores the corresponding RTEPermissionInfo's index in the query's
list of the latter.
ExecutorCheckPerms_hook has gained another List * argument; the
signature is now:
typedef bool (*ExecutorCheckPerms_hook_type) (List *rangeTable,
List *rtePermInfos,
bool ereport_on_violation);
The first argument is no longer used by any in-core uses of the hook,
but we leave it in place because there may be other implementations that
do. Implementations should likely scan the rtePermInfos list to
determine which operations to allow or deny.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqGjJDmUhDSfv-U2qhKJjt9ST7Xh9JXC_irsAQ1TAUsJYg@mail.gmail.com
9d9c02ccd added window "run conditions", which allows the evaluation of
monotonic window functions to be skipped when the run condition is no
longer true. Prior to this commit, once the run condition was no longer
true and we stopped evaluating the window functions, we simply just left
the ecxt_aggvalues[] and ecxt_aggnulls[] arrays alone to store whatever
value was stored there the last time the window function was evaluated.
Leaving a stale value in there isn't really a problem on 64-bit builds as
all of the window functions which we recognize as monotonic all return
int8, which is passed by value on 64-bit builds. However, on 32-bit
builds, this was a problem as the value stored in the ecxt_values[]
element would be a by-ref value and it would be pointing to some memory
which would get reset once the tuple context is destroyed. Since the
WindowAgg node will output these values in the resulting tupleslot, this
could be problematic for the top-level WindowAgg node which must look at
these values to filter out the rows that don't meet its filter condition.
Here we fix this by just zeroing the ecxt_aggvalues[] and setting the
ecxt_aggnulls[] array to true when the run condition first becomes false.
This results in the WindowAgg's output having NULLs for the WindowFunc's
columns rather than the stale or pointer pointing to possibly freed
memory. These tuples with the NULLs can only make it as far as the
top-level WindowAgg node before they're filtered out. To ensure that
these tuples *are* always filtered out, we now insist that OpExprs making
up the run condition are strict OpExprs. Currently, all the window
functions which the planner recognizes as monotonic return INT8 and the
operator which is used for the run condition must be a member of a btree
opclass. In reality, these restrictions exclude nothing that's built-in
to Postgres and are unlikely to exclude anyone's custom operators due to
the requirement that the operator is part of a btree opclass. It would be
unusual if those were not strict.
Reported-by: Sergey Shinderuk, using valgrind
Reviewed-by: Richard Guo, Sergey Shinderuk
Discussion: https://postgr.es/m/29184c50-429a-ebd7-f1fb-0589c6723a35@postgrespro.ru
Backpatch-through: 15, where 9d9c02ccd was added
A couple of places weren't up to speed for this. By sheer good
luck, we didn't fail but just selected a non-memoized join plan,
at least in the test case we have. Nonetheless, it's a bug,
and I'm not quite sure that it couldn't have worse consequences
in other examples. So back-patch to v14 where Memoize came in.
Richard Guo
Discussion: https://postgr.es/m/CAMbWs48GkNom272sfp0-WeD6_0HSR19BJ4H1c9ZKSfbVnJsvRg@mail.gmail.com
Just because I'm a neatnik, and I'm currently working on
code in this area. It annoys me to not be able to pgindent
my patches without working around unrelated changes.
It neglected to recurse to the subpath, meaning you'd get back
a path identical to the input. This could produce wrong query
results if the omission meant that the subpath fails to enforce
some join clause it should be enforcing. We don't have a test
case for this at the moment, but the code is obviously broken
and the fix is equally obvious. Back-patch to v14 where
Memoize was introduced.
Richard Guo
Discussion: https://postgr.es/m/CAMbWs4_R=ORpz=Lkn2q3ebPC5EuWyfZF+tmfCPVLBVK5W39mHA@mail.gmail.com
These two functions failed to cover MaterialPath. That's not a
fatal problem, but we can generate better plans in some cases
if we support it.
Tom Lane and Richard Guo
Discussion: https://postgr.es/m/1854233.1669949723@sss.pgh.pa.us
We might fail to generate a partitionwise join, because
reparameterize_path_by_child() does not support all path types.
This should not be a hard failure condition: we should just fall back
to a non-partitioned join. However, generate_partitionwise_join_paths
did not consider this possibility and would emit the (misleading)
error "could not devise a query plan for the given query" if we'd
failed to make any paths for a child join. Fix it to give up on
partitionwise joining if so. (The accepted technique for giving up
appears to be to set rel->nparts = 0, which I find pretty bizarre,
but there you have it.)
I have not added a test case because there'd be little point:
any omissions of this sort that we identify would soon get fixed
by extending reparameterize_path_by_child(), so the test would stop
proving anything. However, right now there is a known test case based
on failure to cover MaterialPath, and with that I've found that this
is broken in all supported versions. Hence, patch all the way back.
Original report and patch by me; thanks to Richard Guo for
identifying a test case that works against committed versions.
Discussion: https://postgr.es/m/1854233.1669949723@sss.pgh.pa.us
The planner will now add a given PartitioPruneInfo to
PlannedStmt.partPruneInfos instead of directly to the
Append/MergeAppend plan node. What gets set instead in the
latter is an index field which points to the list element
of PlannedStmt.partPruneInfos containing the PartitioPruneInfo
belonging to the plan node.
A later commit will make AcquireExecutorLocks() do the initial
partition pruning to determine a minimal set of partitions to be
locked when validating a plan tree and it will need to consult the
PartitioPruneInfos referenced therein to do so. It would be better
for the PartitioPruneInfos to be accessible directly than requiring
a walk of the plan tree to find them, which is easier when it can be
done by simply iterating over PlannedStmt.partPruneInfos.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.com
A future commit will move the checkAsUser field from RangeTblEntry
to a new node that, unlike RTEs, will only be created for tables
mentioned in the query but not for the inheritance child relations
added to the query by the planner. So, checkAsUser value for a
given child relation will have to be obtained by referring to that
for its ancestor mentioned in the query.
In preparation, it seems better to expand the use of RelOptInfo.userid
during planning in place of rte->checkAsUser so that there will be
fewer places to adjust for the above change.
Given that the child-to-ancestor mapping is not available during the
execution of a given "child" ForeignScan node, add a checkAsUser
field to ForeignScan to carry the child relation's RelOptInfo.userid.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqGFCs2uq7VRKi7g+FFKbP6Ea_2_HkgZb2HPhUfaAKT3ng@mail.gmail.com
The JOIN_SEMI case Assert'ed that there are no PlaceHolderVars that
need to be evaluated at the semijoin's RHS, which is wrong because
there could be some in the semijoin's qual condition. However, there
could not be any references further up than that, and within the qual
there is not any way that such a PHV could have gone to null yet, so
we don't really need the PHV and there is no need to avoid making the
RHS-removal optimization. The upshot is that there's no actual bug
in production code, and we ought to just remove this misguided Assert.
While we're here, also drop the JOIN_RIGHT case, which is dead code
because reduce_outer_joins() already got rid of JOIN_RIGHT.
Per bug #17700 from Xin Wen. Uselessness of the JOIN_RIGHT case
pointed out by Richard Guo. Back-patch to v12 where this code
was added.
Discussion: https://postgr.es/m/17700-2b5c10d917c30687@postgresql.org
This switch impacts 9 patterns related to a SQL-mandated special syntax
for function calls:
- LOCALTIME [ ( typmod ) ]
- LOCALTIMESTAMP [ ( typmod ) ]
- CURRENT_TIME [ ( typmod ) ]
- CURRENT_TIMESTAMP [ ( typmod ) ]
- CURRENT_DATE
Five new entries are added to pg_proc to compensate the removal of
SQLValueFunction to provide backward-compatibility and making this
change transparent for the end-user (for example for the attribute
generated when a keyword is specified in a SELECT or in a FROM clause
without an alias, or when specifying something else than an Iconst to
the parser).
The parser included a set of checks coming from the files in charge of
holding the C functions used for the SQLValueFunction calls (as of
transformSQLValueFunction()), which are now moved within each function's
execution path, so this reduces the dependencies between the execution
and the parsing steps. As of this change, all the SQL keywords use the
same paths for their work, relying only on COERCE_SQL_SYNTAX. Like
fb32748, no performance difference has been noticed, while the perf
profiles get reduced with ExecEvalSQLValueFunction() gone.
Bump catalog version.
Reviewed-by: Corey Huinker, Ted Yu
Discussion: https://postgr.es/m/YzaG3MoryCguUOym@paquier.xyz
Implement a data structure that is a List of Bitmapsets, which is
essentially a 2-D boolean array except that the rows need not all
be the same width. Operations such as union and intersection are
meaningful for these, just as they are for Bitmapsets. Eventually
we might build many of the same operations that we have written for
Bitmapsets, but for the first use-case we just need a few.
That first use-case is for antijoin detection: reduce_outer_joins
needs to find the set of Vars that are certain to be non-null in a
successfully joined (not null-extended) left join row, and also
find the set of Vars subject to higher-level IS NULL constraints,
and intersect them. We had been doing this by making Lists of
the Var nodes and then using list_intersect, which works but is
pretty inefficient compared to a bitmapset-like intersection.
Potentially it's O(N^2) if there are a lot of Vars involved,
which fortunately there generally aren't; still it's not great.
Moreover, that method requires the Vars of interest to be exactly
equal() in the join condition and the upper IS NULL condition,
which is problematic for my WIP patch that labels Vars according
to which outer joins have possibly nulled them.
Discussion: https://postgr.es/m/892228.1668437838@sss.pgh.pa.us
Discussion: https://postgr.es/m/CAMbWs4-mvPPCJ1W6iK6dD5HiNwoJdi6mZp=-7mE8N9Sh+cd0tQ@mail.gmail.com
Add a NodeTag field to struct Bitmapset. This is free because of
alignment considerations on 64-bit hardware. While it adds some
space on 32-bit machines, we aren't optimizing for that case anymore.
The advantage is that data structures such as Lists of Bitmapsets
are now first-class objects to the Node infrastructure, and don't
require special-case code to handle.
This patch includes removal of one such special case, in indxpath.c:
bms_equal_any() can now be replaced by list_member(). There may be
more existing code that could be simplified, but I didn't look very
hard. We also get to drop the read_write_ignore annotations on a
couple of RelOptInfo fields.
The outfuncs/readfuncs support is arranged so that nothing changes
in the string representation of a Bitmapset field; therefore, this
doesn't need a catversion bump.
Amit Langote and Tom Lane
Discussion: https://postgr.es/m/109089.1668197158@sss.pgh.pa.us
Instead of dozens of mostly-duplicate pg_foo_aclcheck() functions,
write one common function object_aclcheck() that can handle almost all
of them. We already have all the information we need, such as which
system catalog corresponds to which catalog table and which column is
the ACL column.
There are a few pg_foo_aclcheck() that don't work via the generic
function and have special APIs, so those stay as is.
I also changed most pg_foo_aclmask() functions to static functions,
since they are not used outside of aclchk.c.
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Antonin Houska <ah@cybertec.at>
Discussion: https://www.postgresql.org/message-id/flat/95c30f96-4060-2f48-98b5-a4392d3b6066@enterprisedb.com
The planner simplifies boolean comparisons such as "x = true" and
"x = false" down to "x" and "NOT x" respectively, to have a canonical
form to ease comparisons. However, if we want to use an index on x,
the index AM APIs require us to reconstitute the comparison-operator
form of the indexqual. While that works, in bitmap indexscans the
canonical form of the qual was emitted as a "filter" condition
although it really only needs to be a "recheck" condition, because
create_bitmap_scan_plan didn't recognize the equivalence of that
form with the generated indexqual. booleq() is pretty cheap so that
likely doesn't make very much difference, but it's unsightly so
let's clean it up.
To fix, add a case to predicate_implied_by() to recognize the
equivalence of such clauses. This is a relatively low-cost place to
add a check, and perhaps it will have additional use cases in future.
Richard Guo and Tom Lane, per discussion of bug #17618 from Sindy
Senorita.
Discussion: https://postgr.es/m/17618-7a2240bfaa7e84ae@postgresql.org
We weren't actually using the passed-down list for anything, other
than computing the new value to be passed down further. I (tgl)
probably had the idea that we'd need this data eventually; but
no use-case has emerged in a good long while, so let's just stop
expending useless cycles here.
Richard Guo
Discussion: https://postgr.es/m/CAMbWs48KLy9aBb=sZ5MoNmnqAcGHaW_JTGWLCgoE_uMW7S6C-A@mail.gmail.com
When all of the query's DISTINCT pathkeys have been marked as redundant
due to EquivalenceClasses existing which contain constants, we can just
implement the DISTINCT operation on a query by just limiting the number of
returned rows to 1 instead of performing a Unique on all of the matching
(duplicate) rows.
This applies in cases such as:
SELECT DISTINCT col,col2 FROM tab WHERE col = 1 AND col2 = 10;
If there are any matching rows, then they must all be {1,10}. There's no
point in fetching all of those and running a Unique operator on them to
leave only a single row. Here we effectively just find the first row and
then stop. We are obviously unable to apply this optimization if either
the col = 1 or col2 = 10 were missing from the WHERE clause or if there
were any additional columns in the SELECT clause.
Such queries are probably not all that common, but detecting when we can
apply this optimization amounts to checking if the distinct_pathkeys are
NULL, which is very cheap indeed.
Nothing is done here to check if the query already has a LIMIT clause. If
it does then the plan may end up with 2 Limits nodes. There's no harm in
that and it's probably not worth the complexity to unify them into a
single Limit node.
Author: David Rowley
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/CAApHDvqS0j8RUWRUSgCAXxOqnYjHUXmKwspRj4GzVfOO25ByHA@mail.gmail.com
Discussion: https://postgr.es/m/MEYPR01MB7101CD5DA0A07C9DE2B74850A4239@MEYPR01MB7101.ausprd01.prod.outlook.com
When we decide we need to make a derived clause equating a.x and
b.y, we already will re-use a previously-made clause "a.x = b.y".
But we might instead have "b.y = a.x", which is perfectly usable
because equivclass.c has never promised anything about the
operand order in clauses it builds. Saving construction of a
new RestrictInfo doesn't matter all that much in itself --- but
because we cache selectivity estimates and so on per-RestrictInfo,
there's a possibility of saving a fair amount of duplicative
effort downstream.
Hence, check for commutative matches as well as direct ones when
seeing if we have a pre-existing clause. This changes the visible
clause order in several regression test cases, but they're all
clearly-insignificant changes.
Checking for the reverse operand order is simple enough, but
if we wanted to check for operator OID match we'd need to call
get_commutator here, which is not so cheap. I concluded that
we don't really need the operator check anyway, so I just
removed it. It's unlikely that an opfamily contains more than
one applicable operator for a given pair of operand datatypes;
and if it does they had better give the same answers, so there
seems little need to insist that we use exactly the one
select_equality_operator chose.
Using the current core regression suite as a test case, I see
this change reducing the number of new join clauses built by
create_join_clause from 9673 to 5142 (out of 26652 calls).
So not quite 50% savings, but pretty close to it.
Discussion: https://postgr.es/m/78062.1666735746@sss.pgh.pa.us
Preprocessing of the HAVING clause will reduce havingQual to NIL
if the clause is constant-TRUE. This is one case where that
convention is rather unfortunate, because "HAVING TRUE" is not at all
the same as not having any HAVING clause at all. (Per the SQL spec,
it still forces the query to be grouped.) The planner deals with this
by having a boolean hasHavingQual that records whether havingQual was
originally nonempty; places that just want to check whether HAVING
was specified are supposed to consult that.
I found three places that got that wrong. Fortunately, these could
only affect cost estimates not correctness. It'd be hard even
to demonstrate the errors; for example, the one in allpaths.c would
only matter in a query that has HAVING TRUE but no GROUP BY and no
aggregates, which would require a completely variable-free SELECT
list, making the case probably of only academic interest. Hence,
while these are worth fixing before someone copies the incorrect
coding somewhere more critical, they don't seem worth back-patching.
I didn't bother trying to devise regression tests, either.
Discussion: https://postgr.es/m/2503888.1666042643@sss.pgh.pa.us
The executor will dump core if it's asked to execute a seqscan on
a relation having no table AM, such as a view. While that shouldn't
really happen, it's possible to get there via catalog corruption,
such as a missing ON SELECT rule. It seems worth installing a defense
against that. There are multiple plausible places for such a defense,
but I picked the planner's get_relation_info().
Per discussion of bug #17646 from Kui Liu. Back-patch to v12 where
the tableam APIs were introduced; in older versions you won't get a
SIGSEGV, so it seems less pressing.
Discussion: https://postgr.es/m/17646-70c93cfa40365776@postgresql.org
While directly targetting a foreign table with MERGE was already
expressly forbidden, we failed to catch the case of a partitioned table
that has a foreign table as a partition; and the result if you try is an
incomprehensible error. Fix that by adding a specific check.
Backpatch to 15.
Reported-by: Tatsuhiro Nakamori <bt22nakamorit@oss.nttdata.com>
Discussion: https://postgr.es/m/bt22nakamorit@oss.nttdata.com
In a similar effort to f01592f91, here we mostly rename shadowed local
variables to remove the warnings produced when compiling with
-Wshadow=compatible-local.
This fixes 63 warnings and leaves just 5.
Author: Justin Pryzby, David Rowley
Reviewed-by: Justin Pryzby
Discussion https://postgr.es/m/20220817145434.GC26426%40telsasoft.com
This reverts commit db0d67db24 and
several follow-on fixes. The idea of making a cost-based choice
of the order of the sorting columns is not fundamentally unsound,
but it requires cost information and data statistics that we don't
really have. For example, relying on procost to distinguish the
relative costs of different sort comparators is pretty pointless
so long as most such comparator functions are labeled with cost 1.0.
Moreover, estimating the number of comparisons done by Quicksort
requires more than just an estimate of the number of distinct values
in the input: you also need some idea of the sizes of the larger
groups, if you want an estimate that's good to better than a factor of
three or so. That's data that's often unknown or not very reliable.
Worse, to arrive at estimates of the number of calls made to the
lower-order-column comparison functions, the code needs to make
estimates of the numbers of distinct values of multiple columns,
which are necessarily even less trustworthy than per-column stats.
Even if all the inputs are perfectly reliable, the cost algorithm
as-implemented cannot offer useful information about how to order
sorting columns beyond the point at which the average group size
is estimated to drop to 1.
Close inspection of the code added by db0d67db2 shows that there
are also multiple small bugs. These could have been fixed, but
there's not much point if we don't trust the estimates to be
accurate in-principle.
Finally, the changes in cost_sort's behavior made for very large
changes (often a factor of 2 or so) in the cost estimates for all
sorting operations, not only those for multi-column GROUP BY.
That naturally changes plan choices in many situations, and there's
precious little evidence to show that the changes are for the better.
Given the above doubts about whether the new estimates are really
trustworthy, it's hard to summon much confidence that these changes
are better on the average.
Since we're hard up against the release deadline for v15, let's
revert these changes for now. We can always try again later.
Note: in v15, I left T_PathKeyInfo in place in nodes.h even though
it's unreferenced. Removing it would be an ABI break, and it seems
a bit late in the release cycle for that.
Discussion: https://postgr.es/m/TYAPR01MB586665EB5FB2C3807E893941F5579@TYAPR01MB5866.jpnprd01.prod.outlook.com
Autoconf is showing its age, fewer and fewer contributors know how to wrangle
it. Recursive make has a lot of hard to resolve dependency issues and slow
incremental rebuilds. Our home-grown MSVC build system is hard to maintain for
developers not using Windows and runs tests serially. While these and other
issues could individually be addressed with incremental improvements, together
they seem best addressed by moving to a more modern build system.
After evaluating different build system choices, we chose to use meson, to a
good degree based on the adoption by other open source projects.
We decided that it's more realistic to commit a relatively early version of
the new build system and mature it in tree.
This commit adds an initial version of a meson based build system. It supports
building postgres on at least AIX, FreeBSD, Linux, macOS, NetBSD, OpenBSD,
Solaris and Windows (however only gcc is supported on aix, solaris). For
Windows/MSVC postgres can now be built with ninja (faster, particularly for
incremental builds) and msbuild (supporting the visual studio GUI, but
building slower).
Several aspects (e.g. Windows rc file generation, PGXS compatibility, LLVM
bitcode generation, documentation adjustments) are done in subsequent commits
requiring further review. Other aspects (e.g. not installing test-only
extensions) are not yet addressed.
When building on Windows with msbuild, builds are slower when using a visual
studio version older than 2019, because those versions do not support
MultiToolTask, required by meson for intra-target parallelism.
The plan is to remove the MSVC specific build system in src/tools/msvc soon
after reaching feature parity. However, we're not planning to remove the
autoconf/make build system in the near future. Likely we're going to keep at
least the parts required for PGXS to keep working around until all supported
versions build with meson.
Some initial help for postgres developers is at
https://wiki.postgresql.org/wiki/Meson
With contributions from Thomas Munro, John Naylor, Stone Tickle and others.
Author: Andres Freund <andres@anarazel.de>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Author: Peter Eisentraut <peter@eisentraut.org>
Reviewed-By: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://postgr.es/m/20211012083721.hvixq4pnh2pixr3j@alap3.anarazel.de
Make sure that function declarations use names that exactly match the
corresponding names from function definitions in optimizer, parser,
utility, libpq, and "commands" code, as well as in remaining library
code. Do the same for all code related to frontend programs (with the
exception of pg_dump/pg_dumpall related code).
Like other recent commits that cleaned up function parameter names, this
commit was written with help from clang-tidy. Later commits will handle
ecpg and pg_dump/pg_dumpall.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
The header comment for get_cheapest_group_keys_order() claimed that the
output arguments were set to a newly allocated list which may be freed by
the calling function, however, this was not always true as the function
would simply leave these arguments untouched in some cases.
This tripped me up when working on 1349d2790 as I mistakenly assumed I
could perform a list_concat with the output parameters. That turned out
bad due to list_concat modifying the original input lists.
In passing, make it more clear that the number of distinct values is
important to reduce tiebreaks during sorts. Also, explain what the
n_preordered parameter means.
Backpatch-through: 15, where get_cheapest_group_keys_order was introduced.
In 29f45e299, we added support for optimizing the execution of NOT
IN(values) by using a hash table instead of a linear search over the
array. That commit neglected to update the header comment for
convert_saop_to_hashed_saop() to mention this fact. Here we fix that.
Author: James Coleman
Discussion: https://postgr.es/m/CAAaqYe99NUpAPcxgchGstgM23fmiGjqQPot8627YgkBgNt=BfA@mail.gmail.com
Backpatch-through: 15, where 29f45e299 was added.
The planner has to special-case indexes on boolean columns, because
what we need for an indexscan on such a column is a qual of the shape
of "boolvar = pseudoconstant". For plain bool constants, previous
simplification will have reduced this to "boolvar" or "NOT boolvar",
and we have to reverse that if we want to make an indexqual. There is
existing code to do so, but it only fires when the index's opfamily
is BOOL_BTREE_FAM_OID or BOOL_HASH_FAM_OID. Thus extension AMs, or
extension opclasses such as contrib/btree_gin, are out in the cold.
The reason for hard-wiring the set of relevant opfamilies was mostly
to avoid a catalog lookup in a hot code path. We can improve matters
while not taking much of a performance hit by relying on the
hard-wired set when the opfamily OID is visibly built-in, and only
checking the catalogs when dealing with an extension opfamily.
While here, rename IsBooleanOpfamily to IsBuiltinBooleanOpfamily
to remind future users of that macro of its limitations. At some
point we might want to make indxpath.c's improved version of the
test globally accessible, but it's not presently needed elsewhere.
Zongliang Quan and Tom Lane
Discussion: https://postgr.es/m/f293b91d-1d46-d386-b6bb-4b06ff5c667b@yeah.net
The reverts the following and makes some associated cleanups:
commit f79b803dc: Common SQL/JSON clauses
commit f4fb45d15: SQL/JSON constructors
commit 5f0adec25: Make STRING an unreserved_keyword.
commit 33a377608: IS JSON predicate
commit 1a36bc9db: SQL/JSON query functions
commit 606948b05: SQL JSON functions
commit 49082c2cc: RETURNING clause for JSON() and JSON_SCALAR()
commit 4e34747c8: JSON_TABLE
commit fadb48b00: PLAN clauses for JSON_TABLE
commit 2ef6f11b0: Reduce running time of jsonb_sqljson test
commit 14d3f24fa: Further improve jsonb_sqljson parallel test
commit a6baa4bad: Documentation for SQL/JSON features
commit b46bcf7a4: Improve readability of SQL/JSON documentation.
commit 112fdb352: Fix finalization for json_objectagg and friends
commit fcdb35c32: Fix transformJsonBehavior
commit 4cd8717af: Improve a couple of sql/json error messages
commit f7a605f63: Small cleanups in SQL/JSON code
commit 9c3d25e17: Fix JSON_OBJECTAGG uniquefying bug
commit a79153b7a: Claim SQL standard compliance for SQL/JSON features
commit a1e7616d6: Rework SQL/JSON documentation
commit 8d9f9634e: Fix errors in copyfuncs/equalfuncs support for JSON node types.
commit 3c633f32b: Only allow returning string types or bytea from json_serialize
commit 67b26703b: expression eval: Fix EEOP_JSON_CONSTRUCTOR and EEOP_JSONEXPR size.
The release notes are also adjusted.
Backpatch to release 15.
Discussion: https://postgr.es/m/40d2c882-bcac-19a9-754d-4299e1d87ac7@postgresql.org
In a similar effort to f01592f91, here we're targetting fixing the
warnings where we've deemed the shadowing variable to serve a close enough
purpose to the shadowed variable just to reuse the shadowed version and
not declare the shadowing variable at all.
By my count, this takes the warning count from 106 down to 71.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20220825020839.GT2342@telsasoft.com
These should have been included in 421892a19 as these shadowed variable
warnings can also be fixed by adjusting the scope of the shadowed variable
to put the declaration for it in an inner scope.
This is part of the same effort as f01592f91.
By my count, this takes the warning count from 114 down to 106.
Author: David Rowley and Justin Pryzby
Discussion: https://postgr.es/m/CAApHDvrwLGBP%2BYw9vriayyf%3DXR4uPWP5jr6cQhP9au_kaDUhbA%40mail.gmail.com
In a similar effort to f01592f91, here we're targetting fixing the
warnings that -Wshadow=compatible-local produces that we can fix by moving
a variable to an inner scope to stop that variable from being shadowed by
another variable declared somewhere later in the function.
All of the warnings being fixed here are changing the scope of variables
which are being used as an iterator for a "for" loop. In each instance,
the fix happens to be changing the for loop to use the C99 type
initialization. Much of this code likely pre-dates our use of C99.
Reducing the scope of the outer scoped variable seems like the safest way
to fix these. Renaming seems more likely to risk patches using the wrong
variable. Reducing the scope is more likely to result in a compilation
failure after applying some future patch rather than introducing bugs with
it.
By my count, this takes the warning count from 129 down to 114.
Author: Justin Pryzby
Discussion: https://postgr.es/m/CAApHDvrwLGBP%2BYw9vriayyf%3DXR4uPWP5jr6cQhP9au_kaDUhbA%40mail.gmail.com
The present implementations of adjust_appendrel_attrs_multilevel and
its sibling adjust_child_relids_multilevel are very messy, because
they work by reconstructing the relids of the child's immediate
parent and then seeing if that's bms_equal to the relids of the
target parent. Aside from being quite inefficient, this will not
work with planned future changes to make joinrels' relid sets
contain outer-join relids in addition to baserels.
The whole thing can be solved at a stroke by adding explicit parent
and top_parent links to child RelOptInfos, and making these functions
work with RelOptInfo pointers instead of relids. Doing that is
simpler for most callers, too.
In my original version of this patch, I got rid of
RelOptInfo.top_parent_relids on the grounds that it was now redundant.
However, that adds a lot of code churn in places that otherwise would
not need changing, and arguably the extra indirection needed to fetch
top_parent->relids in those places costs something. So this version
leaves that field in place.
Discussion: https://postgr.es/m/553080.1657481916@sss.pgh.pa.us
1349d2790 changed things to make the planner request that the
query_pathkeys contain pathkeys for any ORDER BY / DISTINCT aggregates.
Some code added prior to that commit in db0d67db2 made it so the order
that the pathkeys appear in the group_pathkeys could be changed so that
the GROUP BY could be executed in a more optimal order which minimized
sort comparisons. 1349d2790 had to make sure that the pathkeys for any
ORDER BY / DISTINCT aggregates remained at the end of the groupby_pathkeys
and wasn't reordered, so some code was added to
add_paths_to_grouping_rel() to first strip off any pathkeys belonging to
ORDER BY / DISTINCT aggregates before passing to the function to optimize
the order of the group_pathkeys.
It seems I dropped the ball in 1349d2790 and mistakenly used the untouched
PlannerInfo.group_pathkeys to pass to get_useful_group_keys_orderings()
instead of the version that had the aggregate pathkeys removed. It was
only the code path that was handling creating paths for
partially_grouped_rel which made this mistake. In practice, we'll never
have any extra pathkeys to strip off when processing
partially_grouped_rel as that's only used when considering partial
paths, which we never do when there are ORDER BY / DISTINCT aggregates.
So this is just a hypothetical bug, not a live bug. We already have the
correct pathkeys determined, so it's of no extra cost to pass the
correct variable.
Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/20220817015755.GB26426@telsasoft.com
Make build_joinrel_tlist() responsible for adding PHVs that were
already computed in one or the other input relation, and therefore
change add_placeholders_to_joinrel() to only add PHVs that will be
newly computed in this joinrel's output. This makes the handling
of PHVs in build_joinrel_tlist() more like its handling of plain
Vars, which seems like a good thing on intelligibility grounds
and will simplify planned future changes. There is a purely
cosmetic side-effect that the order of entries in the joinrel's
tlist may change; but since it becomes more like the order of
entries in the input tlists, that's not bad.
The reason it wasn't done like this originally was the potential
cost of looking up PlaceHolderInfo entries to consult ph_needed.
Now that that's O(1) it shouldn't hurt.
Discussion: https://postgr.es/m/1405792.1660677844@sss.pgh.pa.us
Up to now, callers of find_placeholder_info() were required to pass
a flag indicating if it's OK to make a new PlaceHolderInfo. That'd
be fine if the callers had free choice, but they do not. Once we
begin deconstruct_jointree() it's no longer OK to make more PHIs;
while callers before that always want to create a PHI if it's not
there already. So there's no freedom of action, only the opportunity
to cause bugs by creating PHIs too late. Let's get rid of that in
favor of adding a state flag PlannerInfo.placeholdersFrozen, which
we can set at the point where it's no longer OK to make more PHIs.
This patch also simplifies a couple of call sites that were using
complicated logic to avoid calling find_placeholder_info() as much
as possible. Now that that lookup is O(1) thanks to the previous
commit, the extra bitmap manipulations are probably a net negative.
Discussion: https://postgr.es/m/1405792.1660677844@sss.pgh.pa.us
Up to now we've just searched the placeholder_list when we want to
find the PlaceHolderInfo with a given ID. While there's no evidence
of that being a problem in the field, an upcoming patch will add
find_placeholder_info() calls in build_joinrel_tlist(), which seems
likely to make it more of an issue: a joinrel emitting lots of
PlaceHolderVars would incur O(N^2) cost, and we might be building
a lot of joinrels in complex queries. Hence, add an array that
can be indexed directly by phid to make the lookups constant-time.
Discussion: https://postgr.es/m/1405792.1660677844@sss.pgh.pa.us
The standard way to check for list emptiness is to compare the
List pointer to NIL; our list code goes out of its way to ensure
that that is the only representation of an empty list. (An
acceptable alternative is a plain boolean test for non-null
pointer, but explicit mention of NIL is usually preferable.)
Various places didn't get that memo and expressed the condition
with list_length(), which might not be so bad except that there
were such a variety of ways to check it exactly: equal to zero,
less than or equal to zero, less than one, yadda yadda. In the
name of code readability, let's standardize all those spellings
as "list == NIL" or "list != NIL". (There's probably some
microscopic efficiency gain too, though few of these look to be
at all performance-critical.)
A very small number of cases were left as-is because they seemed
more consistent with other adjacent list_length tests that way.
Peter Smith, with bikeshedding from a number of us
Discussion: https://postgr.es/m/CAHut+PtQYe+ENX5KrONMfugf0q6NHg4hR5dAhqEXEc2eefFeig@mail.gmail.com
Commit fac1b470a thought we could check for set-returning functions
by testing only the top-level node in an expression tree. This is
wrong in itself, and to make matters worse it encouraged others
to make the same mistake, by exporting tlist.c's special-purpose
IS_SRF_CALL() as a widely-visible macro. I can't find any evidence
that anyone's taken the bait, but it was only a matter of time.
Use expression_returns_set() instead, and stuff the IS_SRF_CALL()
genie back in its bottle, this time with a warning label. I also
added a couple of cross-reference comments.
After a fair amount of fooling around, I've despaired of making
a robust test case that exposes the bug reliably, so no test case
here. (Note that the test case added by fac1b470a is itself
broken, in that it doesn't notice if you remove the code change.
The repro given by the bug submitter currently doesn't fail either
in v15 or HEAD, though I suspect that may indicate an unrelated bug.)
Per bug #17564 from Martijn van Oosterhout. Back-patch to v13,
as the faulty patch was.
Discussion: https://postgr.es/m/17564-c7472c2f90ef2da3@postgresql.org
ORDER BY / DISTINCT aggreagtes have, since implemented in Postgres, been
executed by always performing a sort in nodeAgg.c to sort the tuples in
the current group into the correct order before calling the transition
function on the sorted tuples. This was not great as often there might be
an index that could have provided pre-sorted input and allowed the
transition functions to be called as the rows come in, rather than having
to store them in a tuplestore in order to sort them once all the tuples
for the group have arrived.
Here we change the planner so it requests a path with a sort order which
supports the most amount of ORDER BY / DISTINCT aggregate functions and
add new code to the executor to allow it to support the processing of
ORDER BY / DISTINCT aggregates where the tuples are already sorted in the
correct order.
Since there can be many ORDER BY / DISTINCT aggregates in any given query
level, it's very possible that we can't find an order that suits all of
these aggregates. The sort order that the planner chooses is simply the
one that suits the most aggregate functions. We take the most strictly
sorted variation of each order and see how many aggregate functions can
use that, then we try again with the order of the remaining aggregates to
see if another order would suit more aggregate functions. For example:
SELECT agg(a ORDER BY a),agg2(a ORDER BY a,b) ...
would request the sort order to be {a, b} because {a} is a subset of the
sort order of {a,b}, but;
SELECT agg(a ORDER BY a),agg2(a ORDER BY c) ...
would just pick a plan ordered by {a} (we give precedence to aggregates
which are earlier in the targetlist).
SELECT agg(a ORDER BY a),agg2(a ORDER BY b),agg3(a ORDER BY b) ...
would choose to order by {b} since two aggregates suit that vs just one
that requires input ordered by {a}.
Author: David Rowley
Reviewed-by: Ronan Dunklau, James Coleman, Ranier Vilela, Richard Guo, Tom Lane
Discussion: https://postgr.es/m/CAApHDvpHzfo92%3DR4W0%2BxVua3BUYCKMckWAmo-2t_KiXN-wYH%3Dw%40mail.gmail.com
The select_outer_pathkeys_for_merge function made an attempt to build the
merge join pathkeys in the same order as query_pathkeys. This was done as
it may have led to no sort being required for an ORDER BY or GROUP BY
clause in the upper planner. However, this restriction seems overly
strict as it required that we match the query_pathkeys entirely or we
don't bother putting the merge join pathkeys in that order.
Here we relax this rule so that we use a prefix of the query_pathkeys
providing that prefix matches all of the join quals. This may provide the
upper planner with partially sorted input which will allow the use of
incremental sorts instead of full sorts.
Author: David Rowley
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/CAApHDvrtZu0PHVfDPFM4Yx3jNR2Wuwosv+T2zqa7LrhhBr2rRg@mail.gmail.com
Two callers of generate_useful_gather_paths were testing the wrong
thing when deciding whether to call that function: they checked for
being at the top of the current join subproblem, rather than being at
the actual top join. This'd result in failing to construct parallel
paths for a sub-join for which they might be useful.
While set_rel_pathlist() isn't actively broken, it seems best to
make its identical-in-intention test for this be like the other two.
This has been wrong all along, but given the lack of field complaints
I'm hesitant to back-patch into stable branches; we usually prefer
to avoid non-bug-fix changes in plan choices in minor releases.
It seems not too late for v15 though.
Richard Guo, reviewed by Antonin Houska and Tom Lane
Discussion: https://postgr.es/m/CAMbWs4-mH8Zf87-w+3P2J=nJB+5OyicO28ia9q_9o=Lamf_VHg@mail.gmail.com
Commit 4f658dc8 provided the traditional BSD fls() function in
src/port/fls.c so it could be used in several places. Later we added a
bunch of similar facilities in pg_bitutils.h, based on compiler
builtins that map to hardware instructions. It's a bit confusing to
have both 1-based and 0-based variants of this operation in use in
different parts of the tree, and neither is blessed by a standard.
Let's drop fls.c and the configure probe, and reuse the newer code.
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CA%2BhUKG%2B7dSX1XF8yFGmYk-%3D48dbjH2kmzZj16XvhbrWP-9BzRg%40mail.gmail.com
This is mostly just to get outfuncs.c support for them, so that
the agginfos and aggtransinfos lists can be dumped when dumping
the contents of PlannerInfo.
While here, improve some related comments; notably, clean up
obsolete comments left over from when preprocess_minmax_aggregates
had to make its own scan of the query tree.
Discussion: https://postgr.es/m/742479.1658160504@sss.pgh.pa.us
setrefs.c contains logic to discard no-op SubqueryScan nodes, that is,
ones that have no qual to check and copy the input targetlist unchanged.
(Formally it's not very nice to be applying such optimizations so late
in the planner, but there are practical reasons for it; mostly that we
can't unify relids between the subquery and the parent query until we
flatten the rangetable during setrefs.c.) This behavior falsifies our
previous cost estimates, since we would've charged cpu_tuple_cost per
row just to pass data through the node. Most of the time that's little
enough to not matter, but there are cases where this effect visibly
changes the plan compared to what you would've gotten with no
sub-select.
To improve the situation, make the callers of cost_subqueryscan tell
it whether they think the targetlist is trivial. cost_subqueryscan
already has the qual list, so it can check the other half of the
condition easily. It could make its own determination of tlist
triviality too, but doing so would be repetitive (for callers that
may call it several times) or unnecessarily expensive (for callers
that can determine this more cheaply than a general test would do).
This isn't a 100% solution, because createplan.c also does things
that can falsify any earlier estimate of whether the tlist is
trivial. However, it fixes nearly all cases in practice, if results
for the regression tests are anything to go by.
setrefs.c also contains logic to discard no-op Append and MergeAppend
nodes. We did have knowledge of that behavior at costing time, but
somebody failed to update it when a check on parallel-awareness was
added to the setrefs.c logic. Fix that while we're here.
These changes result in two minor changes in query plans shown in
our regression tests. Neither is relevant to the purposes of its
test case AFAICT.
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/2581077.1651703520@sss.pgh.pa.us
This replaces all MemSet() calls with struct initialization where that
is easily and obviously possible. (For example, some cases have to
worry about padding bits, so I left those.)
(The same could be done with appropriate memset() calls, but this
patch is part of an effort to phase out MemSet(), so it doesn't touch
memset() calls.)
Reviewed-by: Ranier Vilela <ranier.vf@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://www.postgresql.org/message-id/9847b13c-b785-f4e2-75c3-12ec77a3b05c@enterprisedb.com
No members of the buildfarm are using this version of Visual Studio,
resulting in all the code cleaned up here as being mostly dead, and
VS2017 is the oldest version still supported.
More versions could be cut, but the gain would be minimal, while
removing only VS2013 has the advantage to remove from the core code all
the dependencies on the value defined by _MSC_VER, where compatibility
tweaks have accumulated across the years mostly around locales and
strtof(), so that's a nice isolated cleanup.
Note that this commit additionally allows a revert of 3154e16. The
versions of Visual Studio now supported range from 2015 to 2022.
Author: Michael Paquier
Reviewed-by: Juan José Santamaría Flecha, Tom Lane, Thomas Munro, Justin
Pryzby
Discussion: https://postgr.es/m/YoH2IMtxcS3ncWn+@paquier.xyz
Truncating off the end of a freshly copied List is not a very efficient
way of copying the first N elements of a List.
In many of the cases that are updated here, the pattern was only being
used to remove the final element of a List. That's about the best case
for it, but there were many instances where the truncate trimming the List
down much further.
4cc832f94 added list_copy_head(), so let's use it in cases where it's
useful.
Author: David Rowley
Discussion: https://postgr.es/m/1986787.1657666922%40sss.pgh.pa.us
There are a few things that we could do a little better within
get_cheapest_group_keys_order():
1. We should be using list_free() rather than pfree() on a List.
2. We should use for_each_from() instead of manually coding a for loop to
skip the first n elements of a List
3. list_truncate(list_copy(...), n) is not a great way to copy the first n
elements of a list. Let's invent list_copy_head() for that. That way we
don't need to copy the entire list just to truncate it directly
afterwards.
4. We can simplify finding the cheapest cost by setting the cheapest cost
variable to DBL_MAX. That allows us to skip special-casing the initial
iteration of the loop.
Author: David Rowley
Discussion: https://postgr.es/m/CAApHDvrGyL3ft8waEkncG9y5HDMu5TFFJB1paoTC8zi9YK97Nw@mail.gmail.com
Backpatch-through: 15, where get_cheapest_group_keys_order was added.
This function can be called from mark_async_capable_plan(), a helper
function for create_append_plan(), before set_subqueryscan_references(),
to determine the triviality of a SubqueryScan that is a child of an
Append plan node, which is done before doing finalize_plan() on the
SubqueryScan (if necessary) and set_plan_references() on the subplan,
unlike when called from set_subqueryscan_references(). The reason why
this is safe wouldn't be that obvious, so add comments explaining this.
Follow-up for commit c2bb02bc2.
Reviewed by Zhihong Yu.
Discussion: https://postgr.es/m/CAPmGK17%2BGiJBthC6va7%2B9n6t75e-M1N0U18YB2G1B%2BE5OdrNTA%40mail.gmail.com
9d9c02ccd added code to allow the executor to take shortcuts when quals
on monotonic window functions guaranteed that once the qual became false
it could never become true again. When possible, baserestrictinfo quals
are converted to become these quals, which we call run conditions.
Unfortunately, in 9d9c02ccd, I forgot to update
remove_unused_subquery_outputs to teach it about these run conditions.
This could cause a WindowFunc column which was unused in the target list
but referenced by an upper-level WHERE clause to be removed from the
subquery when the qual in the WHERE clause was converted into a window run
condition. Because of this, the entire WindowClause would be removed from
the query resulting in additional rows making it into the resultset when
they should have been filtered out by the WHERE clause.
Here we fix this by recording which target list items in the subquery have
run conditions. That gets passed along to remove_unused_subquery_outputs
to tell it not to remove these items from the target list.
Bug: #17495
Reported-by: Jeremy Evans
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/17495-7ffe2fa0b261b9fa@postgresql.org
Several places in the planner tried to clamp a double value to fit
in a "long" by doing
(long) Min(x, (double) LONG_MAX);
This is subtly incorrect, because it casts LONG_MAX to double and
potentially back again. If long is 64 bits then the double value
is inexact, and the platform might round it up to LONG_MAX+1
resulting in an overflow and an undesirably negative output.
While it's not hard to rewrite the expression into a safe form,
let's put it into a common function to reduce the risk of someone
doing it wrong in future.
In principle this is a bug fix, but since the problem could only
manifest with group count estimates exceeding 2^63, it seems unlikely
that anyone has actually hit this or will do so anytime soon. We're
fixing it mainly to satisfy fuzzer-type tools. That being the case,
a HEAD-only fix seems sufficient.
Andrey Lepikhov
Discussion: https://postgr.es/m/ebbc2efb-7ef9-bf2f-1ada-d6ec48f70e58@postgrespro.ru
In order to estimate the cache hit ratio of a Memoize node, one of the
inputs we require is the estimated number of times the Memoize node will
be rescanned. The higher this number, the large the cache hit ratio is
likely to become. Unfortunately, the value being passed as the number of
"calls" to the Memoize was incorrectly using the Nested Loop's
outer_path->parent->rows instead of outer_path->rows. This failed to
account for the fact that the outer_path might be parameterized by some
upper-level Nested Loop.
This problem could lead to Memoize plans appearing more favorable than
they might actually be. It could also lead to extended executor startup
times when work_mem values were large due to the planner setting overly
large MemoizePath->est_entries resulting in the Memoize hash table being
initially made much larger than might be required.
Fix this simply by passing outer_path->rows rather than
outer_path->parent->rows. Also, adjust the expected regression test
output for a plan change.
Reported-by: Pavel Stehule
Author: David Rowley
Discussion: https://postgr.es/m/CAFj8pRAMp%3DQsMi6sPQJ4W3hczoFJRvyXHJV3AZAZaMyTVM312Q%40mail.gmail.com
Backpatch-through: 14, where Memoize was introduced
This follows in the footsteps of commit 2591ee8ec by removing one more
ill-advised shortcut from planning of GroupingFuncs. It's true that
we don't intend to execute the argument expression(s) at runtime, but
we still have to process any Vars appearing within them, or we risk
failure at setrefs.c time (or more fundamentally, in EXPLAIN trying
to print such an expression). Vars in upper plan nodes have to have
referents in the next plan level, whether we ever execute 'em or not.
Per bug #17479 from Michael J. Sullivan. Back-patch to all supported
branches.
Richard Guo
Discussion: https://postgr.es/m/17479-6260deceaf0ad304@postgresql.org
SubqueryScan was always getting labeled with a rowcount estimate
appropriate for non-parallel cases. However, nodes that are
underneath a Gather should be treated as processing only one
worker's share of the rows, whether the particular node is explicitly
parallel-aware or not. Most non-scan-level node types get this
right automatically because they base their rowcount estimate on
that of their input sub-Path(s). But SubqueryScan didn't do that,
instead using the whole-relation rowcount estimate as if it were
a non-parallel-aware scan node. If there is a parallel-aware node
below the SubqueryScan, this is wrong, and it results in inflating
the cost estimates for nodes above the SubqueryScan, which can cause
us to not choose a parallel plan, or choose a silly one --- as indeed
is visible in the one regression test whose results change with this
patch. (Although that plan tree appears to contain no SubqueryScans,
there were some in it before setrefs.c deleted them.)
To fix, use path->subpath->rows not baserel->tuples as the number
of input tuples we'll process. This requires estimating the quals'
selectivity afresh, which is slightly annoying; but it shouldn't
really add much cost thanks to the caching done in RestrictInfo.
This is pretty clearly a bug fix, but I'll refrain from back-patching
as people might not appreciate plan choices changing in stable branches.
The fact that it took us this long to identify the bug suggests that
it's not a major problem.
Per report from bucoo, though this is not his proposed patch.
Discussion: https://postgr.es/m/202204121457159307248@sohu.com
mark_async_capable_plan(), which is called from create_append_plan() to
determine whether subplans are async-capable, failed to take into
account that the given subplan created from a given subpath might
include a gating Result node if the subpath is a SubqueryScanPath or
ForeignPath, causing a segmentation fault there when the subplan created
from a SubqueryScanPath includes the Result node, or causing
ExecAsyncRequest() to throw an error about an unrecognized node type
when the subplan created from a ForeignPath includes the Result node,
because in the latter case the Result node was unintentionally
considered as async-capable, but we don't currently support executing
Result nodes asynchronously. Fix by modifying mark_async_capable_plan()
to disable asynchronous execution in such cases. Also, adjust code in
the ProjectionPath case in mark_async_capable_plan(), for consistency
with other cases, and adjust/improve comments there.
is_async_capable_path() added in commit 27e1f1456, which was rewritten
to mark_async_capable_plan() in a later commit, has the same issue,
causing the error at execution mentioned above, so back-patch to v14
where the aforesaid commit went in.
Per report from Justin Pryzby.
Etsuro Fujita, reviewed by Zhihong Yu and Justin Pryzby.
Discussion: https://postgr.es/m/20220408124338.GK24419%40telsasoft.com
inline_cte() expected to find exactly as many references to the
target CTE as its cterefcount indicates. While that should be
accurate for the tree as emitted by the parser, there are some
optimizations that occur upstream of here that could falsify it,
notably removal of unused subquery output expressions.
Trying to make the accounting 100% accurate seems expensive and
doomed to future breakage. It's not really worth it, because
all this code is protecting is downstream assumptions that every
referenced CTE has a plan. Let's convert those assertions to
regular test-and-elog just in case there's some actual problem,
and then drop the failing assertion.
Per report from Tomas Vondra (thanks also to Richard Guo for
analysis). Back-patch to v12 where the faulty code came in.
Discussion: https://postgr.es/m/29196a1e-ed47-c7ca-9be2-b1c636816183@enterprisedb.com
We were setting MERGE source subplan's targetlist by expanding the
individual attributes of the source relation completely, early in the
parse analysis phase. This failed to work when the condition of an
action included a whole-row reference, causing setrefs.c to error out
with
ERROR: variable not found in subplan target lists
because at that point there is nothing to resolve the whole-row
reference with. We can fix this by having preprocess_targetlist expand
the source targetlist for Vars required from the source rel by all
actions. Moreover, by using this expansion mechanism we can do away
with the targetlist expansion in transformMergeStmt, which is good
because then we no longer pull in columns that aren't needed for
anything.
Add a test case for the problem.
While at it, remove some redundant code in preprocess_targetlist():
MERGE was doing separately what is already being done for UPDATE/DELETE,
so we can just rely on the latter and remove the former. (The handling
of inherited rels was different for MERGE, but that was a no-longer-
necessary hack.)
Fix outdated, related comments for fix_join_expr also.
Author: Richard Guo <guofenglinux@gmail.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reported-by: Joe Wildish <joe@lateraljoin.com>
Discussion: https://postgr.es/m/fab3b90a-914d-46a9-beb0-df011ee39ee5@www.fastmail.com
Window functions such as row_number() always return a value higher than
the previously returned value for tuples in any given window partition.
Traditionally queries such as;
SELECT * FROM (
SELECT *, row_number() over (order by c) rn
FROM t
) t WHERE rn <= 10;
were executed fairly inefficiently. Neither the query planner nor the
executor knew that once rn made it to 11 that nothing further would match
the outer query's WHERE clause. It would blindly continue until all
tuples were exhausted from the subquery.
Here we implement means to make the above execute more efficiently.
This is done by way of adding a pg_proc.prosupport function to various of
the built-in window functions and adding supporting code to allow the
support function to inform the planner if the window function is
monotonically increasing, monotonically decreasing, both or neither. The
planner is then able to make use of that information and possibly allow
the executor to short-circuit execution by way of adding a "run condition"
to the WindowAgg to allow it to determine if some of its execution work
can be skipped.
This "run condition" is not like a normal filter. These run conditions
are only built using quals comparing values to monotonic window functions.
For monotonic increasing functions, quals making use of the btree
operators for <, <= and = can be used (assuming the window function column
is on the left). You can see here that once such a condition becomes false
that a monotonic increasing function could never make it subsequently true
again. For monotonically decreasing functions the >, >= and = btree
operators for the given type can be used for run conditions.
The best-case situation for this is when there is a single WindowAgg node
without a PARTITION BY clause. Here when the run condition becomes false
the WindowAgg node can simply return NULL. No more tuples will ever match
the run condition. It's a little more complex when there is a PARTITION
BY clause. In this case, we cannot return NULL as we must still process
other partitions. To speed this case up we pull tuples from the outer
plan to check if they're from the same partition and simply discard them
if they are. When we find a tuple belonging to another partition we start
processing as normal again until the run condition becomes false or we run
out of tuples to process.
When there are multiple WindowAgg nodes to evaluate then this complicates
the situation. For intermediate WindowAggs we must ensure we always
return all tuples to the calling node. Any filtering done could lead to
incorrect results in WindowAgg nodes above. For all intermediate nodes,
we can still save some work when the run condition becomes false. We've
no need to evaluate the WindowFuncs anymore. Other WindowAgg nodes cannot
reference the value of these and these tuples will not appear in the final
result anyway. The savings here are small in comparison to what can be
saved in the top-level WingowAgg, but still worthwhile.
Intermediate WindowAgg nodes never filter out tuples, but here we change
WindowAgg so that the top-level WindowAgg filters out tuples that don't
match the intermediate WindowAgg node's run condition. Such filters
appear in the "Filter" clause in EXPLAIN for the top-level WindowAgg node.
Here we add prosupport functions to allow the above to work for;
row_number(), rank(), dense_rank(), count(*) and count(expr). It appears
technically possible to do the same for min() and max(), however, it seems
unlikely to be useful enough, so that's not done here.
Bump catversion
Author: David Rowley
Reviewed-by: Andy Fan, Zhihong Yu
Discussion: https://postgr.es/m/CAApHDvqvp3At8++yF8ij06sdcoo1S_b2YoaT9D4Nf+MObzsrLQ@mail.gmail.com
In commit 27e1f1456, create_append_plan() only allowed the subplan
created from a given subpath to be executed asynchronously when it was
an async-capable ForeignPath. To extend coverage, this patch handles
cases when the given subpath includes some other Path types as well that
can be omitted in the plan processing, such as a ProjectionPath directly
atop an async-capable ForeignPath, allowing asynchronous execution in
partitioned-scan/partitioned-join queries with non-Var tlist expressions
and more UNION queries.
Andrey Lepikhov and Etsuro Fujita, reviewed by Alexander Pyhalov and
Zhihong Yu.
Discussion: https://postgr.es/m/659c37a8-3e71-0ff2-394c-f04428c76f08%40postgrespro.ru
postgres_fdw would push ORDER BY clauses to the remote side without
verifying that the sort operator is safe to ship. Moreover, it failed
to print a suitable USING clause if the sort operator isn't default
for the sort expression's type. The net result of this is that the
remote sort might not have anywhere near the semantics we expect,
which'd be disastrous for locally-performed merge joins in particular.
We addressed similar issues in the context of ORDER BY within an
aggregate function call in commit 7012b132d, but failed to notice
that query-level ORDER BY was broken. Thus, much of the necessary
logic already existed, but it requires refactoring to be usable
in both cases.
Back-patch to all supported branches. In HEAD only, remove the
core code's copy of find_em_expr_for_rel, which is no longer used
and really should never have been pushed into equivclass.c in the
first place.
Ronan Dunklau, per report from David Rowley;
reviews by David Rowley, Ranier Vilela, and myself
Discussion: https://postgr.es/m/CAApHDvr4OeC2DBVY--zVP83-K=bYrTD7F8SZDhN4g+pj2f2S-A@mail.gmail.com
When evaluating a query with a multi-column GROUP BY clause using sort,
the cost may be heavily dependent on the order in which the keys are
compared when building the groups. Grouping does not imply any ordering,
so we're allowed to compare the keys in arbitrary order, and a Hash Agg
leverages this. But for Group Agg, we simply compared keys in the order
as specified in the query. This commit explores alternative ordering of
the keys, trying to find a cheaper one.
In principle, we might generate grouping paths for all permutations of
the keys, and leave the rest to the optimizer. But that might get very
expensive, so we try to pick only a couple interesting orderings based
on both local and global information.
When planning the grouping path, we explore statistics (number of
distinct values, cost of the comparison function) for the keys and
reorder them to minimize comparison costs. Intuitively, it may be better
to perform more expensive comparisons (for complex data types etc.)
last, because maybe the cheaper comparisons will be enough. Similarly,
the higher the cardinality of a key, the lower the probability we’ll
need to compare more keys. The patch generates and costs various
orderings, picking the cheapest ones.
The ordering of group keys may interact with other parts of the query,
some of which may not be known while planning the grouping. E.g. there
may be an explicit ORDER BY clause, or some other ordering-dependent
operation, higher up in the query, and using the same ordering may allow
using either incremental sort or even eliminate the sort entirely.
The patch generates orderings and picks those minimizing the comparison
cost (for various pathkeys), and then adds orderings that might be
useful for operations higher up in the plan (ORDER BY, etc.). Finally,
it always keeps the ordering specified in the query, on the assumption
the user might have additional insights.
This introduces a new GUC enable_group_by_reordering, so that the
optimization may be disabled if needed.
The original patch was proposed by Teodor Sigaev, and later improved and
reworked by Dmitry Dolgov. Reviews by a number of people, including me,
Andrey Lepikhov, Claudio Freire, Ibrar Ahmed and Zhihong Yu.
Author: Dmitry Dolgov, Teodor Sigaev, Tomas Vondra
Reviewed-by: Tomas Vondra, Andrey Lepikhov, Claudio Freire, Ibrar Ahmed, Zhihong Yu
Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru
Discussion: https://postgr.es/m/CA%2Bq6zcW_4o2NC0zutLkOJPsFt80megSpX_dVRo6GK9PC-Jx_Ag%40mail.gmail.com
This introduces the SQL/JSON functions for querying JSON data using
jsonpath expressions. The functions are:
JSON_EXISTS()
JSON_QUERY()
JSON_VALUE()
All of these functions only operate on jsonb. The workaround for now is
to cast the argument to jsonb.
JSON_EXISTS() tests if the jsonpath expression applied to the jsonb
value yields any values. JSON_VALUE() must return a single value, and an
error occurs if it tries to return multiple values. JSON_QUERY() must
return a json object or array, and there are various WRAPPER options for
handling scalar or multi-value results. Both these functions have
options for handling EMPTY and ERROR conditions.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
MERGE performs actions that modify rows in the target table using a
source table or query. MERGE provides a single SQL statement that can
conditionally INSERT/UPDATE/DELETE rows -- a task that would otherwise
require multiple PL statements. For example,
MERGE INTO target AS t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND t.balance > s.delta THEN
UPDATE SET balance = t.balance - s.delta
WHEN MATCHED THEN
DELETE
WHEN NOT MATCHED AND s.delta > 0 THEN
INSERT VALUES (s.sid, s.delta)
WHEN NOT MATCHED THEN
DO NOTHING;
MERGE works with regular tables, partitioned tables and inheritance
hierarchies, including column and row security enforcement, as well as
support for row and statement triggers and transition tables therein.
MERGE is optimized for OLTP and is parameterizable, though also useful
for large scale ETL/ELT. MERGE is not intended to be used in preference
to existing single SQL commands for INSERT, UPDATE or DELETE since there
is some overhead. MERGE can be used from PL/pgSQL.
MERGE does not support targetting updatable views or foreign tables, and
RETURNING clauses are not allowed either. These limitations are likely
fixable with sufficient effort. Rewrite rules are also not supported,
but it's not clear that we'd want to support them.
Author: Pavan Deolasee <pavan.deolasee@gmail.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Author: Amit Langote <amitlangote09@gmail.com>
Author: Simon Riggs <simon.riggs@enterprisedb.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Andres Freund <andres@anarazel.de> (earlier versions)
Reviewed-by: Peter Geoghegan <pg@bowt.ie> (earlier versions)
Reviewed-by: Robert Haas <robertmhaas@gmail.com> (earlier versions)
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>
Discussion: https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com
Discussion: https://postgr.es/m/20201231134736.GA25392@alvherre.pgsql
This patch introduces the SQL/JSON standard constructors for JSON:
JSON()
JSON_ARRAY()
JSON_ARRAYAGG()
JSON_OBJECT()
JSON_OBJECTAGG()
For the most part these functions provide facilities that mimic
existing json/jsonb functions. However, they also offer some useful
additional functionality. In addition to text input, the JSON() function
accepts bytea input, which it will decode and constuct a json value from.
The other functions provide useful options for handling duplicate keys
and null values.
This series of patches will be followed by a consolidated documentation
patch.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
This introduces some of the building blocks used by the SQL/JSON
constructor and query functions. Specifically, it provides node
executor and grammar support for the FORMAT JSON [ENCODING foo]
clause, and values decorated with it, and for the RETURNING clause.
The following SQL/JSON patches will leverage these.
Nikita Glukhov (who probably deserves an award for perseverance).
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
flatten_join_alias_vars_mutator counted attnums, but didn't
do anything with the count (no doubt it did at one time).
Noted by buildfarm member seawasp.
Up to now, the planner estimated the size of a recursive query's
worktable as 10 times the size of the non-recursive term. It's hard
to see how to do significantly better than that automatically, but
we can give users control over the multiplier to allow tuning for
specific use-cases. The default behavior remains the same.
Simon Riggs
Discussion: https://postgr.es/m/CANbhV-EuaLm4H3g0+BSTYHEGxJj3Kht0R+rJ8vT57Dejnh=_nA@mail.gmail.com
This introduces some of the building blocks used by the SQL/JSON
constructor and query functions. Specifically, it provides node
executor and grammar support for the FORMAT JSON [ENCODING foo]
clause, and values decorated with it, and for the RETURNING clause.
The following SQL/JSON patches will leverage these.
Nikita Glukhov (who probably deserves an award for perseverance).
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup. Erik Rijkers, Zihong Yu and
Himanshu Upadhyaya.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
The planner needs to treat GroupingFunc like Aggref for many purposes,
in particular with respect to processing of the argument expressions,
which are not to be evaluated at runtime. A few places hadn't gotten
that memo, notably including subselect.c's processing of outer-level
aggregates. This resulted in assertion failures or wrong plans for
cases in which a GROUPING() construct references an outer aggregation
level.
Also fix missing special cases for GroupingFunc in cost_qual_eval
(resulting in wrong cost estimates for GROUPING(), although it's
not clear that that would affect plan shapes in practice) and in
ruleutils.c (resulting in excess parentheses in pretty-print mode).
Per bug #17088 from Yaoguang Chen. Back-patch to all supported
branches.
Richard Guo, Tom Lane
Discussion: https://postgr.es/m/17088-e33882b387de7f5c@postgresql.org
If a RowExpr is marked as returning a named composite type, we aren't
going to consult its colnames list; we'll use the attribute names
shown for the type in pg_attribute. Hence, skip storing that list,
to save a few nanoseconds when copying the expression tree around.
Discussion: https://postgr.es/m/2950001.1638729947@sss.pgh.pa.us
There are three parallel ways to call parse/analyze: with fixed
parameters, with variable parameters, and by supplying your own parser
callback. Some of the involved functions were confusingly named and
made this API structure more confusing. This patch renames some
functions to make this clearer:
parse_analyze() -> parse_analyze_fixedparams()
pg_analyze_and_rewrite() -> pg_analyze_and_rewrite_fixedparams()
(Otherwise one might think this variant doesn't accept parameters, but
in fact all three ways accept parameters.)
pg_analyze_and_rewrite_params() -> pg_analyze_and_rewrite_withcb()
(Before, and also when considering pg_analyze_and_rewrite(), one might
think this is the only way to pass parameters. Moreover, the parser
callback doesn't necessarily need to parse only parameters, it's just
one of the things it could do.)
parse_fixed_parameters() -> setup_parse_fixed_parameters()
parse_variable_parameters() -> setup_parse_variable_parameters()
(These functions don't actually do any parsing, they just set up
callbacks to use during parsing later.)
This patch also adds some const decorations to the fixed-parameters
API, so the distinction from the variable-parameters API is more
clear.
Reviewed-by: Nathan Bossart <bossartn@amazon.com>
Discussion: https://www.postgresql.org/message-id/flat/c67ce276-52b4-0239-dc0e-39875bf81840@enterprisedb.com
createplan.c tries to save a runtime projection step by specifying
a scan plan node's output as being exactly the table's columns, or
index's columns in the case of an index-only scan, if there is not a
reason to do otherwise. This logic did not previously pay attention
to whether an index's columns are returnable. That worked, sort of
accidentally, until commit 9a3ddeb51 taught setrefs.c to reject plans
that try to read a non-returnable column. I have no desire to loosen
setrefs.c's new check, so instead adjust use_physical_tlist() to not
try to optimize this way when there are non-returnable column(s).
Per report from Ryan Kelly. Like the previous patch, back-patch
to all supported branches.
Discussion: https://postgr.es/m/CAHUie24ddN+pDNw7fkhNrjrwAX=fXXfGZZEHhRuofV_N_ftaSg@mail.gmail.com
8edd0e794 added some code to remove Append and MergeAppend nodes when they
contained a single child node. As it turned out, this was unsafe to do
when the Append/MergeAppend was parallel_aware and the child node was not.
Removing the Append/MergeAppend, in this case, could lead to the child plan
being called multiple times by parallel workers when it was unsafe to do
so.
Here we fix this by just not removing the Append/MergeAppend when the
parallel_aware flag of the parent and child node don't match.
Reported-by: Yura Sokolov
Bug: #17335
Discussion: https://postgr.es/m/b59605fecb20ba9ea94e70ab60098c237c870628.camel%40postgrespro.ru
Backpatch-through: 12, where 8edd0e794 was first introduced
This fixes a set of issues that have accumulated over the past months
(or years) in various code areas. Most fixes are related to some recent
additions, as of the development of v15.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20220124030001.GQ23027@telsasoft.com
In the normal configuration where GEQO_DEBUG isn't defined,
recent clang versions have started to complain that geqo_main.c
accumulates the edge_failures count but never does anything
with it. As a minimal back-patchable fix, insert a void cast
to silence this warning. (I'd speculated about ripping out the
GEQO_DEBUG logic altogether, but I don't think we'd wish to
back-patch that.)
Per recently-established project policy, this is a candidate
for back-patching into out-of-support branches: it suppresses
an annoying compiler warning but changes no behavior. Hence,
back-patch all the way to 9.2.
Discussion: https://postgr.es/m/CA+hUKGLTSZQwES8VNPmWO9AO0wSeLt36OCPDAZTccT1h7Q7kTQ@mail.gmail.com
In sort_inner_and_outer we iterate a list of PathKey elements, but the
variable is declared as (List *). This mistake is benign, because we
only pass the pointer to lcons() and never dereference it.
This exists since ~2004, but it's confusing. So fix and backpatch to all
supported branches.
Backpatch-through: 10
Discussion: https://postgr.es/m/bf3a6ea1-a7d8-7211-0669-189d5c169374%40enterprisedb.com
The need for this was foreseen long ago, but when record_eq
actually became hashable (in commit 01e658fa7), we missed updating
this spot.
Per bug #17363 from Elvis Pranskevichus. Back-patch to v14 where
the faulty commit came in.
Discussion: https://postgr.es/m/17363-f6d42fd0d726be02@postgresql.org
Add pg_statistic_ext_data.stxdinherit flag, so that for each extended
statistics definition we can store two versions of data - one for the
relation alone, one for the whole inheritance tree. This is analogous to
pg_statistic.stainherit, but we failed to include such flag in catalogs
for extended statistics, and we had to work around it (see commits
859b3003de, 36c4bc6e72 and 20b9fa308e).
This changes the relationship between the two catalogs storing extended
statistics objects (pg_statistic_ext and pg_statistic_ext_data). Until
now, there was a simple 1:1 mapping - for each definition there was one
pg_statistic_ext_data row, and this row was inserted while creating the
statistics (and then updated during ANALYZE). With the stxdinherit flag,
we don't know how many rows there will be (child relations may be added
after the statistics object is defined), so there may be up to two rows.
We could make CREATE STATISTICS to always create both rows, but that
seems wasteful - without partitioning we only need stxdinherit=false
rows, and declaratively partitioned tables need only stxdinherit=true.
So we no longer initialize pg_statistic_ext_data in CREATE STATISTICS,
and instead make that a responsibility of ANALYZE. Which is what we do
for regular statistics too.
Patch by me, with extensive improvements and fixes by Justin Pryzby.
Author: Tomas Vondra, Justin Pryzby
Reviewed-by: Tomas Vondra, Justin Pryzby
Discussion: https://postgr.es/m/20210923212624.GI831%40telsasoft.com
When building append paths, we've been looking only at startup and total
costs for the paths. When building fractional paths that may eliminate
the cheapest one, because it may be dominated by two separate paths (one
for startup, one for total cost).
This extends generate_orderedappend_paths() to also consider which paths
have lowest fractional cost. Currently we only consider paths matching
pathkeys - in the future this may be improved by also considering paths
that are only partially sorted, with an incremental sort on top.
Original report of an issue by Arne Roland, patch by me (based on a
suggestion by Tom Lane).
Reviewed-by: Arne Roland, Zhihong Yu
Discussion: https://postgr.es/m/e8f9ec90-546d-e948-acce-0525f3e92773%40enterprisedb.com
Discussion: https://postgr.es/m/1581042da8044e71ada2d6e3a51bf7bb%40index.de
Since this function is defined to accept pg_node_tree values, it could
get applied to any nodetree that can appear in a cataloged pg_node_tree
column. Some such cases can't be supported --- for example, its API
doesn't allow providing referents for more than one relation --- but
we should try to throw a user-facing error rather than an internal
error when encountering such a case.
In support of this, extend expression_tree_walker/mutator to be sure
they'll work on any such node tree (which basically means adding
support for relpartbound node types). That allows us to run pull_varnos
and check for the case of multiple relations before we start processing
the tree. The alternative of changing the low-level error thrown for an
out-of-range varno isn't appealing, because that could mask actual bugs
in other usages of ruleutils.
Per report from Justin Pryzby. This is basically cosmetic, so no
back-patch.
Discussion: https://postgr.es/m/20211219205422.GT17618@telsasoft.com
We can revert the code changes of commit b5febc1d1 now, because
commit 9a3ddeb51 installed a real solution for the difficulty
that b5febc1d1 just dodged, namely that the planner might pick
the wrong one of several index columns nominally containing the
same value. It only matters which one we pick if we pick one
that's not returnable, and that mistake is now foreclosed.
Although both of the aforementioned commits were back-patched,
I don't feel a need to take any risk by back-patching this one.
The cases that it improves are very corner-ish.
Discussion: https://postgr.es/m/3179992.1641150853@sss.pgh.pa.us
Commit 4ace45677 failed to fix the problem fully, because the
same issue of attempting to fetch a non-returnable index column
can occur when rechecking the indexqual after using a lossy index
operator. Moreover, it broke EXPLAIN for such indexquals (which
indicates a gap in our test cases :-().
Revert the code changes of 4ace45677 in favor of adding a new field
to struct IndexOnlyScan, containing a version of the indexqual that
can be executed against the index-returned tuple without using any
non-returnable columns. (The restrictions imposed by check_index_only
guarantee this is possible, although we may have to recompute indexed
expressions.) Support construction of that during setrefs.c
processing by marking IndexOnlyScan.indextlist entries as resjunk
if they can't be returned, rather than removing them entirely.
(We could alternatively require setrefs.c to look up the IndexOptInfo
again, but abusing resjunk this way seems like a reasonably safe way
to avoid needing to do that.)
This solution isn't great from an API-stability standpoint: if there
are any extensions out there that build IndexOnlyScan structs directly,
they'll be broken in the next minor releases. However, only a very
invasive extension would be likely to do such a thing. There's no
change in the Path representation, so typical planner extensions
shouldn't have a problem.
As before, back-patch to all supported branches.
Discussion: https://postgr.es/m/3179992.1641150853@sss.pgh.pa.us
Discussion: https://postgr.es/m/17350-b5bdcf476e5badbb@postgresql.org
If an index has both returnable and non-returnable columns, and one of
the non-returnable columns is an expression using a Var that is in a
returnable column, then a query returning that expression could result
in an index-only scan plan that attempts to read the non-returnable
column, instead of recomputing the expression from the returnable
column as intended.
To fix, redefine the "indextlist" list of an IndexOnlyScan plan node
as containing null Consts in place of any non-returnable columns.
This solves the problem by preventing setrefs.c from falsely matching
to such entries. The executor is happy since it only cares about the
exposed types of the entries, and ruleutils.c doesn't care because a
correct plan won't reference those entries. I considered some other
ways to prevent setrefs.c from doing the wrong thing, but this way
seems good since (a) it allows a very localized fix, (b) it makes
the indextlist structure more compact in many cases, and (c) the
indextlist is now a more faithful representation of what the index AM
will actually produce, viz. nulls for any non-returnable columns.
This is easier to hit since we introduced included columns, but it's
possible to construct failing examples without that, as per the
added regression test. Hence, back-patch to all supported branches.
Per bug #17350 from Louis Jachiet.
Discussion: https://postgr.es/m/17350-b5bdcf476e5badbb@postgresql.org
Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code. In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.
xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy. It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random(). It is not cryptographically strong, but neither
are the functions it replaces.
Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself
Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
It's possible that a subplan below a Memoize node contains a parameter
from above the Memoize node. If this parameter changes then cache entries
may become out-dated due to the new parameter value.
Previously Memoize was mistakenly not aware of this. We fix this here by
flushing the cache whenever a parameter that's not part of the cache
key changes.
Bug: #17213
Reported by: Elvis Pranskevichus
Author: David Rowley
Discussion: https://postgr.es/m/17213-988ed34b225a2862@postgresql.org
Backpatch-through: 14, where Memoize was added
It's possible that a subplan below a Memoize node contains a parameter
from above the Memoize node. If this parameter changes then cache entries
may become out-dated due to the new parameter value.
Previously Memoize was mistakenly not aware of this. We fix this here by
flushing the cache whenever a parameter that's not part of the cache
key changes.
Bug: #17213
Reported by: Elvis Pranskevichus
Author: David Rowley
Discussion: https://postgr.es/m/17213-988ed34b225a2862@postgresql.org
Backpatch-through: 14, where Memoize was added
Memoize would always use the hash equality operator for the cache key
types to determine if the current set of parameters were the same as some
previously cached set. Certain types such as floating points where -0.0
and +0.0 differ in their binary representation but are classed as equal by
the hash equality operator may cause problems as unless the join uses the
same operator it's possible that whichever join operator is being used
would be able to distinguish the two values. In which case we may
accidentally return in the incorrect rows out of the cache.
To fix this here we add a binary mode to Memoize to allow it to the
current set of parameters to previously cached values by comparing
bit-by-bit rather than logically using the hash equality operator. This
binary mode is always used for LATERAL joins and it's used for normal
joins when any of the join operators are not hashable.
Reported-by: Tom Lane
Author: David Rowley
Discussion: https://postgr.es/m/3004308.1632952496@sss.pgh.pa.us
Backpatch-through: 14, where Memoize was added
In v14, because we don't have a field in RestrictInfo to cache both the
left and right type's hash equality operator, we just restrict the scope
of Memoize to only when the left and right types of a RestrictInfo are the
same.
In master we add another field to RestrictInfo and cache both hash
equality operators.
Reported-by: Jaime Casanova
Author: David Rowley
Discussion: https://postgr.es/m/20210929185544.GB24346%40ahch-to
Backpatch-through: 14
As in commits 6301c3ada and e9d9ba2a4, avoid doing repetitive
list_delete_first() operations, since that would be expensive when
there are many files waiting to be unlinked. This is a slightly
larger change than in those cases. We have to keep the list state
valid for calls to AbsorbSyncRequests(), so it's necessary to invent a
"canceled" field instead of immediately deleting PendingUnlinkEntry
entries. Also, because we might not be able to process all the
entries, we need a new list primitive list_delete_first_n().
list_delete_first_n() is almost list_copy_tail(), but it modifies the
input List instead of making a new copy. I found a couple of existing
uses of the latter that could profitably use the new function. (There
might be more, but the other callers look like they probably shouldn't
overwrite the input List.)
As before, back-patch to v13.
Discussion: https://postgr.es/m/CD2F0E7F-9822-45EC-A411-AE56F14DEA9F@amazon.com
If a function-in-FROM laterally references the output of some sub-SELECT
earlier in the FROM clause, and we are able to flatten that sub-SELECT
into the outer query, the expression(s) copied into the function RTE
missed being processed by eval_const_expressions. This'd lead to trouble
and probable crashes at execution if such expressions contained
named-argument function call syntax or functions with defaulted arguments.
The bug is masked if the query contains any explicit JOIN syntax, which
may help explain why we'd not noticed.
Per bug #17227 from Bernd Dorn. This is an oversight in commit 7266d0997,
so back-patch to v13 where that came in.
Discussion: https://postgr.es/m/17227-5a28ed1512189fa4@postgresql.org
Several mistakes have piled in the code comments over the time,
including incorrect grammar, function names and simple typos. This
commit takes care of a portion of these.
No backpatch is done as this is only cosmetic.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20210924215827.GS831@telsasoft.com
Commit 55dc86eca changed pull_varnos to use (if possible) the associated
ph_eval_at for a PlaceHolderVar. I missed a fine point though: we might
be looking at a PHV in the quals or tlist of a child appendrel, in which
case we need to compute a ph_eval_at value that's been translated in the
same way that the PHV itself has been (cf. adjust_appendrel_attrs).
Fortunately, enough info is available in the PlaceHolderInfo to make
such translation possible without additional outside data, so we don't
need another round of uglification of planner APIs. This is a little
bit complicated, but since it's a hard-to-hit corner case, I'm not much
worried about adding cycles here.
Per report from Jaime Casanova. Back-patch to v12, like the previous
commit.
Discussion: https://postgr.es/m/20210915230959.GB17635@ahch-to
Up to now the size of a query's rangetable has been limited by the
constants INNER_VAR et al, which mustn't be equal to any real
rangetable index. 65000 doubtless seemed like enough for anybody,
and it still is orders of magnitude larger than the number of joins
we can realistically handle. However, we need a rangetable entry
for each child partition that is (or might be) processed by a query.
Queries with a few thousand partitions are getting more realistic,
so that the day when that limit becomes a problem is in sight,
even if it's not here yet. Hence, let's raise the limit.
Rather than just increase the values of INNER_VAR et al, this patch
adopts the approach of making them small negative values, so that
rangetables could theoretically become as long as INT_MAX.
The bulk of the patch is concerned with changing Var.varno and some
related variables from "Index" (unsigned int) to plain "int". This
is basically cosmetic, with little actual effect other than to help
debuggers print their values nicely. As such, I've only bothered
with changing places that could actually see INNER_VAR et al, which
the parser and most of the planner don't. We do have to be careful
in places that are performing less/greater comparisons on varnos,
but there are very few such places, other than the IS_SPECIAL_VARNO
macro itself.
A notable side effect of this patch is that while it used to be
possible to add INNER_VAR et al to a Bitmapset, that will now
draw an error. I don't see any likelihood that it wouldn't be a
bug to include these fake varnos in a bitmapset of real varnos,
so I think this is all to the good.
Although this touches outfuncs/readfuncs, I don't think a catversion
bump is required, since stored rules would never contain Vars
with these fake varnos.
Andrey Lepikhov and Tom Lane, after a suggestion by Peter Eisentraut
Discussion: https://postgr.es/m/43c7f2f5-1e27-27aa-8c65-c91859d15190@postgrespro.ru
It's possible for us to copy an AlternativeSubPlan expression node
into multiple places, for example the scan quals of several
partition children. Then it's possible that we choose a different
one of the alternatives as optimal in each place. Commit 41efb8340
failed to consider this scenario, so its attempt to remove "unused"
subplans could remove subplans that were still used elsewhere.
Fix by delaying the removal logic until we've examined all the
AlternativeSubPlans in a given query level. (This does assume that
AlternativeSubPlans couldn't get copied to other query levels, but
for the foreseeable future that's fine; cf qual_is_pushdown_safe.)
Per report from Rajkumar Raghuwanshi. Back-patch to v14
where the faulty logic came in.
Discussion: https://postgr.es/m/CAKcux6==O3NNZC3bZ2prRYv3cjm3_Zw1GfzmOjEVqYN4jub2+Q@mail.gmail.com
All the code paths simplified here were already using a boolean or used
an expression that led to zero or one, making the extra bits
unnecessary.
Author: Justin Pryzby
Reviewed-by: Tom Lane, Michael Paquier, Peter Smith
Discussion: https://postgr.es/m/20210428182936.GE27406@telsasoft.com
When starting to use a query parsetree loaded from the catalogs,
we must begin by applying AcquireRewriteLocks(), to obtain the same
relation locks that the parser would have gotten if the query were
entered interactively, and to do some other cleanup such as dealing
with later-dropped columns. New-style SQL functions are just as
subject to this rule as other stored parsetrees; however, of the
places dealing with such functions, only init_sql_fcache had gotten
the memo. In particular, if we successfully inlined a new-style
set-returning SQL function that contained any relation references,
we'd either get an assertion failure or attempt to use those
relation(s) sans locks.
I also added AcquireRewriteLocks calls to fmgr_sql_validator and
print_function_sqlbody. Desultory experiments didn't demonstrate any
failures in those, but I suspect that I just didn't try hard enough.
Certainly we don't expect nearby code paths to operate without locks.
On the same logic of it-ought-to-have-the-same-effects-as-the-old-code,
call pg_rewrite_query() in fmgr_sql_validator, too. It's possible
that neither code path there needs to bother with rewriting, but
doing the analysis to prove that is beyond my goals for today.
Per bug #17161 from Alexander Lakhin.
Discussion: https://postgr.es/m/17161-048a1cdff8422800@postgresql.org
We've supported parallel aggregation since e06a38965. At the time, we
didn't quite get around to also adding parallel DISTINCT. So, let's do
that now.
This is implemented by introducing a two-phase DISTINCT. Phase 1 is
performed on parallel workers, rows are made distinct there either by
hashing or by sort/unique. The results from the parallel workers are
combined and the final distinct phase is performed serially to get rid of
any duplicate rows that appear due to combining rows for each of the
parallel workers.
Author: David Rowley
Reviewed-by: Zhihong Yu
Discussion: https://postgr.es/m/CAApHDvrjRxVKwQN0he79xS+9wyotFXL=RmoWqGGO2N45Farpgw@mail.gmail.com
959d00e9d added the ability to make use of an Append node instead of a
MergeAppend when we wanted to perform a scan of a partitioned table and
the required sort order was the same as the partitioned keys and the
partitioned table was defined in such a way that earlier partitions were
guaranteed to only contain lower-order values than later partitions.
However, previously we didn't allow these ordered partition scans for
LIST partitioned table when there were any partitions that allowed
multiple Datums. This was a very cheap check to make and we could likely
have done a little better by checking if there were interleaved
partitions, but at the time we didn't have visibility about which
partitions were pruned, so we still may have disallowed cases where all
interleaved partitions were pruned.
Since 475dbd0b7, we now have knowledge of pruned partitions, we can do a
much better job inside partitions_are_ordered().
Here we pass which partitions survived partition pruning into
partitions_are_ordered() and, for LIST partitioning, have it check to see
if any live partitions exist that are also in the new "interleaved_parts"
field defined in PartitionBoundInfo.
For RANGE partitioning we can relax the code which caused the partitions
to be unordered if a DEFAULT partition existed. Since we now know which
partitions were pruned, partitions_are_ordered() now returns true when the
DEFAULT partition was pruned.
Reviewed-by: Amit Langote, Zhihong Yu
Discussion: https://postgr.es/m/CAApHDvrdoN_sXU52i=QDXe2k3WAo=EVry29r2+Tq2WYcn2xhEA@mail.gmail.com
For partitioned tables with large numbers of partitions where queries are
able to prune all but a very small number of partitions, the time spent in
the planner looping over RelOptInfo.part_rels checking for non-NULL
RelOptInfos could become a large portion of the overall planning time.
Here we add a Bitmapset that records the non-pruned partitions. This
allows us to more efficiently skip the pruned partitions by looping over
the Bitmapset.
This will cause a very slight slow down in cases where no or not many
partitions could be pruned, however, those cases are already slow to plan
anyway and the overhead of looping over the Bitmapset would be
unmeasurable when compared with the other tasks such as path creation for
a large number of partitions.
Reviewed-by: Amit Langote, Zhihong Yu
Discussion: https://postgr.es/m/CAApHDvqnPx6JnUuPwaf5ao38zczrAb9mxt9gj4U1EKFfd4AqLA@mail.gmail.com
Adjust the header comment in get_agg_clause_costs so that it matches what
the function currently does. No recursive searching has been done ever
since 0a2bc5d61. It also does not determine the aggtranstype like the
comment claimed. That's all done in preprocess_aggref().
preprocess_aggref also now determines the numOrderedAggs, so remove the
mention that get_agg_clause_costs also calculates "counts".
Normally, since this is just an adjustment of a comment it might not be
worth back-patching, but since this code is new to PG14 and that version
is still in beta, then it seems worth having the comments match.
Discussion: https://postgr.es/m/CAApHDvrrGrTJFPELrjx0CnDtz9B7Jy2XYW3Z2BKifAWLSaJYwQ@mail.gmail.com
Backpatch-though: 14
The point of introducing the hash_mem_multiplier GUC was to let users
reproduce the old behavior of hash aggregation, i.e. that it could use
more than work_mem at need. However, the implementation failed to get
the job done on Win64, where work_mem is clamped to 2GB to protect
various places that calculate memory sizes using "long int". As
written, the same clamp was applied to hash_mem. This resulted in
severe performance regressions for queries requiring a bit more than
2GB for hash aggregation, as they now spill to disk and there's no
way to stop that.
Getting rid of the work_mem restriction seems like a good idea, but
it's a big job and could not conceivably be back-patched. However,
there's only a fairly small number of places that are concerned with
the hash_mem value, and it turns out to be possible to remove the
restriction there without too much code churn or any ABI breaks.
So, let's do that for now to fix the regression, and leave the
larger task for another day.
This patch does introduce a bit more infrastructure that should help
with the larger task, namely pg_bitutils.h support for working with
size_t values.
Per gripe from Laurent Hasson. Back-patch to v13 where the
behavior change came in.
Discussion: https://postgr.es/m/997817.1627074924@sss.pgh.pa.us
Discussion: https://postgr.es/m/MN2PR15MB25601E80A9B6D1BA6F592B1985E39@MN2PR15MB2560.namprd15.prod.outlook.com
As of v14, pg_depend contains almost 7000 "pin" entries recording
the OIDs of built-in objects. This is a fair amount of bloat for
every database, and it adds time to pg_depend lookups as well as
initdb. We can get rid of all of those entries in favor of an OID
range check, i.e. "OIDs below FirstUnpinnedObjectId are pinned".
(template1 and the public schema are exceptions. Those exceptions
are now wired into IsPinnedObject() instead of initdb's code for
filling pg_depend, but it's the same amount of cruft either way.)
The contents of pg_shdepend are modified likewise.
Discussion: https://postgr.es/m/3737988.1618451008@sss.pgh.pa.us
This allows Param substitution to produce just the same result
as writing a constant value literally would have done. While
it hardly matters so far as the current core code is concerned,
extensions might take more interest in node location fields.
Julien Rouhaud
Discussion: https://postgr.es/m/20170311220932.GJ15188@nol.local
"Result Cache" was never a great name for this node, but nobody managed
to come up with another name that anyone liked enough. That was until
David Johnston mentioned "Node Memoization", which Tom Lane revised to
just "Memoize". People seem to like "Memoize", so let's do the rename.
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/20210708165145.GG1176@momjian.us
Backpatch-through: 14, where Result Cache was introduced
Commit 7266d0997 added code to pull up simple constant function
results, converting the RTE_FUNCTION RTE to a dummy RTE_RESULT
RTE since it no longer need be scanned. But I forgot to clear
the LATERAL flag if the RTE has it set. If the function reduced
to a constant, it surely contains no lateral references so this
simplification is logically OK. It's needed because various other
places will Assert that RESULT RTEs aren't LATERAL.
Per bug #17097 from Yaoguang Chen. Back-patch to v13 where the
faulty code came in.
Discussion: https://postgr.es/m/17097-3372ef9f798fc94f@postgresql.org
Similar to 50e17ad28, which allowed hash tables to be used for IN clauses
with a set of constants, here we add the same feature for NOT IN clauses.
NOT IN evaluates the same as: WHERE a <> v1 AND a <> v2 AND a <> v3.
Obviously, if we're using a hash table we must be exactly equivalent to
that and return the same result taking into account that either side of
the condition could contain a NULL. This requires a little bit of
special handling to make work with the hash table version.
When processing NOT IN, the ScalarArrayOpExpr's operator will be the <>
operator. To be able to build and lookup a hash table we must use the
<>'s negator operator. The planner checks if that exists and is hashable
and sets the relevant fields in ScalarArrayOpExpr to instruct the executor
to use hashing.
Author: David Rowley, James Coleman
Reviewed-by: James Coleman, Zhihong Yu
Discussion: https://postgr.es/m/CAApHDvoF1mum_FRk6D621edcB6KSHBi2+GAgWmioj5AhOu2vwQ@mail.gmail.com
Previously, all CustomScan providers had to support projections,
but there may be cases where this is inconvenient. Add a flag
bit to say if it's supported.
Important item for the release notes: this is non-backwards-compatible
since the default is now to assume that CustomScan providers can't
project, instead of assuming that they can. It's fail-soft, but could
result in visible performance penalties due to adding unnecessary
Result nodes.
Sven Klemm, reviewed by Aleksander Alekseev; some cosmetic fiddling
by me.
Discussion: https://postgr.es/m/CAMCrgp1kyakOz6c8aKhNDJXjhQ1dEjEnp+6KNT3KxPrjNtsrDg@mail.gmail.com
Joel Jacobson reported that deep nesting of trivial (flattenable)
views results in O(N^3) growth of planning time for N-deep nesting.
It turns out that a large chunk of this cost comes from copying around
the "subquery" sub-tree of each view's RTE_SUBQUERY RTE. But once we
have successfully flattened the subquery, we don't need that anymore,
because the planner isn't going to do anything else interesting with
that RTE. We already zap the subquery pointer during setrefs.c (cf.
add_rte_to_flat_rtable), but it's useless baggage earlier than that
too. Clearing the pointer as soon as pull_up_simple_subquery is done
with the RTE reduces the cost from O(N^3) to O(N^2); which is still
not great, but it's quite a lot better. Further improvements will
require rethinking of the RTE data structure, which is being considered
in another thread.
Patch by me; thanks to Dean Rasheed for review.
Discussion: https://postgr.es/m/797aff54-b49b-4914-9ff9-aa42564a4d7d@www.fastmail.com
Commit 2453ea142 redefined pg_proc.proargtypes to include the types of
OUT parameters, for procedures only. While that had some advantages
for implementing the SQL-spec behavior of DROP PROCEDURE, it was pretty
disastrous from a number of other perspectives. Notably, since the
primary key of pg_proc is name + proargtypes, this made it possible to
have multiple procedures with identical names + input arguments and
differing output argument types. That would make it impossible to call
any one of the procedures by writing just NULL (or "?", or any other
data-type-free notation) for the output argument(s). The change also
seems likely to cause grave confusion for client applications that
examine pg_proc and expect the traditional definition of proargtypes.
Hence, revert the definition of proargtypes to what it was, and
undo a number of complications that had been added to support that.
To support the SQL-spec behavior of DROP PROCEDURE, when there are
no argmode markers in the command's parameter list, we perform the
lookup both ways (that is, matching against both proargtypes and
proallargtypes), succeeding if we get just one unique match.
In principle this could result in ambiguous-function failures
that would not happen when using only one of the two rules.
However, overloading of procedure names is thought to be a pretty
rare usage, so this shouldn't cause many problems in practice.
Postgres-specific code such as pg_dump can defend against any
possibility of such failures by being careful to specify argmodes
for all procedure arguments.
This also fixes a few other bugs in the area of CALL statements
with named parameters, and improves the documentation a little.
catversion bump forced because the representation of procedures
with OUT arguments changes.
Discussion: https://postgr.es/m/3742981.1621533210@sss.pgh.pa.us
Commit 428b260f8 broke planning of cases where row marks are needed
(SELECT FOR UPDATE, etc) and one of the query's tables is a foreign
table that has regular table(s) as inheritance children. We got the
reverse case right, but apparently were thinking that foreign tables
couldn't be inheritance parents. Not so; so we need to be able to
add a CTID junk column while adding a new child, not only a wholerow
junk column.
Back-patch to v12 where the faulty code came in.
Amit Langote
Discussion: https://postgr.es/m/CA+HiwqEmo3FV1LAQ4TVyS2h1WM=kMkZUmbNuZSCnfHvMcUcPeA@mail.gmail.com
create_projection_plan contains a hidden assumption (here made
explicit by an Assert) that a projection-capable Path will yield a
projection-capable Plan. Unfortunately, that assumption is violated
only a few lines away, by create_projection_plan itself. This means
that two stacked ProjectionPaths can yield an outcome where we try to
jam the upper path's tlist into a non-projection-capable child node,
resulting in an invalid plan.
There isn't any good reason to have stacked ProjectionPaths; indeed the
whole concept is faulty, since the set of Vars/Aggs/etc needed by the
upper one wouldn't necessarily be available in the output of the lower
one, nor could the lower one create such values if they weren't
available from its input. Hence, we can fix this by adjusting
create_projection_path to strip any top-level ProjectionPath from the
subpath it's given. (This amounts to saying "oh, we changed our
minds about what we need to project here".)
The test case added here only fails in v13 and HEAD; before that, we
don't attempt to shove the Sort into the parallel part of the plan,
for reasons that aren't entirely clear to me. However, all the
directly-related code looks generally the same as far back as v11,
where the hazard was introduced (by d7c19e62a). So I've got no faith
that the same type of bug doesn't exist in v11 and v12, given the
right test case. Hence, back-patch the code changes, but not the
irrelevant test case, into those branches.
Per report from Bas Poot.
Discussion: https://postgr.es/m/534fca83789c4a378c7de379e9067d4f@politie.nl
Commit e717a9a18 introduced a code path that bypassed the call of
get_expr_result_type, which is not good because we need its rettupdesc
result to pass to check_sql_fn_retval. We'd failed to notice right
away because the code path in which check_sql_fn_retval uses that
argument is fairly hard to reach in this context. It's not impossible
though, and in any case inline_function would have no business
assuming that check_sql_fn_retval doesn't need that value.
To fix, move get_expr_result_type out of the if-block, which in
turn requires moving the construction of the dummy FuncExpr
out of it.
Per report from Ranier Vilela. (I'm bemused by the lack of any
compiler complaints...)
Discussion: https://postgr.es/m/CAEudQAqBqQpQ3HruWAGU_7WaMJ7tntpk0T8k_dVtNB46DqdBgw@mail.gmail.com
Result Cache, added in 9eacee2e6 neglected to properly adjust the plan
references in setrefs.c. This could lead to the following error during
EXPLAIN:
ERROR: cannot decompile join alias var in plan tree
Fix that.
Bug: 17030
Reported-by: Hans Buschmann
Discussion: https://postgr.es/m/17030-5844aecae42fe223@postgresql.org
Code added in 9e215378d to disable building of Result Cache paths when
not all join conditions are part of the parameterization of a unique
join failed to first check if the inner path's param_info was set before
checking the param_info's ppi_clauses.
Add a check for NULL values here and just bail on trying to build the
path if param_info is NULL. lateral_vars are not considered when
deciding if the join is unique, so we're not missing out on doing the
optimization when there are lateral_vars and no param_info.
Reported-by: Coverity, via Tom Lane
Discussion: https://postgr.es/m/457998.1621779290@sss.pgh.pa.us
When the planner considered using a Result Cache node to cache results
from the inner side of a Nested Loop Join, it failed to consider that the
inner path's parameterization may not be the entire join condition. If
the join was marked as inner_unique then we may accidentally put the cache
in singlerow mode. This meant that entries would be marked as complete
after caching the first row. That was wrong as if only part of the join
condition was parameterized then the uniqueness of the unique join was not
guaranteed at the Result Cache's level. The uniqueness is only guaranteed
after Nested Loop applies the join filter. If subsequent rows were found,
this would lead to:
ERROR: cache entry already complete
This could have been fixed by only putting the cache in singlerow mode if
the entire join condition was parameterized. However, Nested Loop will
only read its inner side so far as the first matching row when the join is
unique, so that might mean we never get an opportunity to mark cache
entries as complete. Since non-complete cache entries are useless for
subsequent lookups, we just don't bother considering a Result Cache path
in this case.
In passing, remove the XXX comment that claimed the above ERROR might be
better suited to be an Assert. After there being an actual case which
triggered it, it seems better to keep it an ERROR.
Reported-by: David Christensen
Discussion: https://postgr.es/m/CAOxo6X+dy-V58iEPFgst8ahPKEU+38NZzUuc+a7wDBZd4TrHMQ@mail.gmail.com
Also "make reformat-dat-files".
The only change worthy of note is that pgindent messed up the formatting
of launcher.c's struct LogicalRepWorkerId, which led me to notice that
that struct wasn't used at all anymore, so I just took it out.
It's unusual to have any resjunk columns in an ON CONFLICT ... UPDATE
list, but it can happen when MULTIEXPR_SUBLINK SubPlans are present.
If it happens, the ON CONFLICT UPDATE code path would end up storing
tuples that include the values of the extra resjunk columns. That's
fairly harmless in the short run, but if new columns are added to
the table then the values would become accessible, possibly leading
to malfunctions if they don't match the datatypes of the new columns.
This had escaped notice through a confluence of missing sanity checks,
including
* There's no cross-check that a tuple presented to heap_insert or
heap_update matches the table rowtype. While it's difficult to
check that fully at reasonable cost, we can easily add assertions
that there aren't too many columns.
* The output-column-assignment cases in execExprInterp.c lacked
any sanity checks on the output column numbers, which seems like
an oversight considering there are plenty of assertion checks on
input column numbers. Add assertions there too.
* We failed to apply nodeModifyTable's ExecCheckPlanOutput() to
the ON CONFLICT UPDATE tlist. That wouldn't have caught this
specific error, since that function is chartered to ignore resjunk
columns; but it sure seems like a bad omission now that we've seen
this bug.
In HEAD, the right way to fix this is to make the processing of
ON CONFLICT UPDATE tlists work the same as regular UPDATE tlists
now do, that is don't add "SET x = x" entries, and use
ExecBuildUpdateProjection to evaluate the tlist and combine it with
old values of the not-set columns. This adds a little complication
to ExecBuildUpdateProjection, but allows removal of a comparable
amount of now-dead code from the planner.
In the back branches, the most expedient solution seems to be to
(a) use an output slot for the ON CONFLICT UPDATE projection that
actually matches the target table, and then (b) invent a variant of
ExecBuildProjectionInfo that can be told to not store values resulting
from resjunk columns, so it doesn't try to store into nonexistent
columns of the output slot. (We can't simply ignore the resjunk columns
altogether; they have to be evaluated for MULTIEXPR_SUBLINK to work.)
This works back to v10. In 9.6, projections work much differently and
we can't cheaply give them such an option. The 9.6 version of this
patch works by inserting a JunkFilter when it's necessary to get rid
of resjunk columns.
In addition, v11 and up have the reverse problem when trying to
perform ON CONFLICT UPDATE on a partitioned table. Through a
further oversight, adjust_partition_tlist() discarded resjunk columns
when re-ordering the ON CONFLICT UPDATE tlist to match a partition.
This accidentally prevented the storing-bogus-tuples problem, but
at the cost that MULTIEXPR_SUBLINK cases didn't work, typically
crashing if more than one row has to be updated. Fix by preserving
resjunk columns in that routine. (I failed to resist the temptation
to add more assertions there too, and to do some minor code
beautification.)
Per report from Andres Freund. Back-patch to all supported branches.
Security: CVE-2021-32028
Design problems were discovered in the handling of composite types and
record types that would cause some relevant versions not to be recorded.
Misgivings were also expressed about the use of the pg_depend catalog
for this purpose. We're out of time for this release so we'll revert
and try again.
Commits reverted:
1bf946bd: Doc: Document known problem with Windows collation versions.
cf002008: Remove no-longer-relevant test case.
ef387bed: Fix bogus collation-version-recording logic.
0fb0a050: Hide internal error for pg_collation_actual_version(<bad OID>).
ff942057: Suppress "warning: variable 'collcollate' set but not used".
d50e3b1f: Fix assertion in collation version lookup.
f24b1569: Rethink extraction of collation dependencies.
257836a7: Track collation versions for indexes.
cd6f479e: Add pg_depend.refobjversion.
7d1297df: Remove pg_collation.collversion.
Discussion: https://postgr.es/m/CA%2BhUKGLhj5t1fcjqAu8iD9B3ixJtsTNqyCCD4V0aTO9kAKAjjA%40mail.gmail.com
During queries coming from ri_triggers.c, we need to omit partitions
that are marked pending detach -- otherwise, the RI query is tricked
into allowing a row into the referencing table whose corresponding row
is in the detached partition. Which is bogus: once the detach operation
completes, the row becomes an orphan.
However, the code was not doing that in repeatable-read transactions,
because relcache kept a copy of the partition descriptor that included
the partition, and used it in the RI query. This commit changes the
partdesc cache code to only keep descriptors that aren't dependent on
a snapshot (namely: those where no detached partition exist, and those
where detached partitions are included). When a partdesc-without-
detached-partitions is requested, we create one afresh each time; also,
those partdescs are stored in PortalContext instead of
CacheMemoryContext.
find_inheritance_children gets a new output *detached_exist boolean,
which indicates whether any partition marked pending-detach is found.
Its "include_detached" input flag is changed to "omit_detached", because
that name captures desired the semantics more naturally.
CreatePartitionDirectory() and RelationGetPartitionDesc() arguments are
identically renamed.
This was noticed because a buildfarm member that runs with relcache
clobbering, which would not keep the improperly cached partdesc, broke
one test, which led us to realize that the expected output of that test
was bogus. This commit also corrects that expected output.
Author: Amit Langote <amitlangote09@gmail.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/3269784.1617215412@sss.pgh.pa.us
I didn't particularly like this function name, as it fails to
express what's going on. Also, returning the sort expression
alone isn't too helpful --- typically, a caller would also
need some other fields of the EquivalenceMember. But the
sole caller really only needs a bool result, so let's make
it "bool relation_can_be_sorted_early()".
Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c651f@swarm64.com
An oversight introduced by the incremental-sort patches caused
"could not find pathkey item to sort" errors in some situations
where a sort key involves an aggregate or window function.
The basic problem here is that find_em_expr_usable_for_sorting_rel
isn't properly modeling what prepare_sort_from_pathkeys will do
later. Rather than hoping we can keep those functions in sync,
let's refactor so that they actually share the code for
identifying a suitable sort expression.
With this refactoring, tlist.c's tlist_member_ignore_relabel
is unused. I removed it in HEAD but left it in place in v13,
in case any extensions are using it.
Per report from Luc Vlaming. Back-patch to v13 where the
problem arose.
James Coleman and Tom Lane
Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c651f@swarm64.com
Commit e717a9a18 changed the longstanding rule that prosrc is NOT NULL
because when a SQL-language function is written in SQL-standard style,
we don't currently have anything useful to put there. This seems a poor
decision though, as it could easily have negative impacts on external
PLs (opening them to crashes they didn't use to have, for instance).
SQL-function-related code can just as easily test "is prosqlbody not
null" as "is prosrc null", so there's no real gain there either.
Hence, revert the NOT NULL marking removal and adjust related logic.
For now, we just put an empty string into prosrc for SQL-standard
functions. Maybe we'll have a better idea later, although the
history of things like pg_attrdef.adsrc suggests that it's not
easy to maintain a string equivalent of a node tree.
This also adds an assertion that queryDesc->sourceText != NULL
to standard_ExecutorStart. We'd been silently relying on that
for awhile, so let's make it less silent.
Also fix some overlooked documentation and test cases.
Discussion: https://postgr.es/m/2197698.1617984583@sss.pgh.pa.us
ScalarArrayOpExprs with "useOr=true" and a set of Consts on the righthand
side have traditionally been evaluated by using a linear search over the
array. When these arrays contain large numbers of elements then this
linear search could become a significant part of execution time.
Here we add a new method of evaluating ScalarArrayOpExpr expressions to
allow them to be evaluated by first building a hash table containing each
element, then on subsequent evaluations, we just probe that hash table to
determine if there is a match.
The planner is in charge of determining when this optimization is possible
and it enables it by setting hashfuncid in the ScalarArrayOpExpr. The
executor will only perform the hash table evaluation when the hashfuncid
is set.
This means that not all cases are optimized. For example CHECK constraints
containing an IN clause won't go through the planner, so won't get the
hashfuncid set. We could maybe do something about that at some later
date. The reason we're not doing it now is from fear that we may slow
down cases where the expression is evaluated only once. Those cases can
be common, for example, a single row INSERT to a table with a CHECK
constraint containing an IN clause.
In the planner, we enable this when there are suitable hash functions for
the ScalarArrayOpExpr's operator and only when there is at least
MIN_ARRAY_SIZE_FOR_HASHED_SAOP elements in the array. The threshold is
currently set to 9.
Author: James Coleman, David Rowley
Reviewed-by: David Rowley, Tomas Vondra, Heikki Linnakangas
Discussion: https://postgr.es/m/CAAaqYe8x62+=wn0zvNKCj55tPpg-JBHzhZFFc6ANovdqFw7-dA@mail.gmail.com
Tom Lane
Alvaro Herrera
David Rowley
Peter Eisentraut
Michael Paquier
Bruce Momjian
Andrew Dunstan
Andres Freund
Peter Geoghegan
Thomas Munro
Etsuro Fujita
Tomas Vondra