The partition pruning logic assumed that "b IS NOT true" was exactly the
same as "b IS FALSE". This is not the case when considering NULL values.
Fix this so we correctly include any partition which could hold NULL
values for the NOT case.
Additionally, this fixes a bug in the partition pruning code which handles
partitioned tables partitioned like ((NOT boolcol)). This is a seemingly
unlikely schema design, and it was untested and also broken.
Here we add tests for the ((NOT boolcol)) case and insert some actual data
into those tables and verify we do get the correct rows back when running
queries. I've also adjusted the existing boolpart tests to include some
data and verify we get the correct results too.
Both the bugs being fixed here could lead to incorrect query results with
fewer rows being returned than expected. No additional rows could have
been returned accidentally.
In passing, remove needless ternary expression. It's more simple just to
pass !is_not_clause to makeBoolConst(). It makes sense to do this so the
code is consistent with the bug fix in the "else if" condition just below.
David Kimura did submit a patch to fix the first of the issues here, but
that's not what's being committed here.
Reported-by: David Kimura
Reviewed-by: Richard Guo, David Kimura
Discussion: https://postgr.es/m/CAHnPFjQ5qxs6J_p+g8=ww7GQvfn71_JE+Tygj0S7RdRci1uwPw@mail.gmail.com
Backpatch-through: 11, all supported versions
When extracting an attr from a cached tuple in the syscache with
SysCacheGetAttr the isnull parameter must be checked in case the
attr cannot be NULL. For cases when this is known beforehand, a
wrapper is introduced which perform the errorhandling internally
on behalf of the caller, invoking an elog in case of a NULL attr.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/AD76405E-DB45-46B6-941F-17B1EB3A9076@yesql.se
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
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
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
guc.c has grown to be one of our largest .c files, making it
a bottleneck for compilation. It's also acquired a bunch of
knowledge that'd be better kept elsewhere, because of our not
very good habit of putting variable-specific check hooks here.
Hence, split it up along these lines:
* guc.c itself retains just the core GUC housekeeping mechanisms.
* New file guc_funcs.c contains the SET/SHOW interfaces and some
SQL-accessible functions for GUC manipulation.
* New file guc_tables.c contains the data arrays that define the
built-in GUC variables, along with some already-exported constant
tables.
* GUC check/assign/show hook functions are moved to the variable's
home module, whenever that's clearly identifiable. A few hard-
to-classify hooks ended up in commands/variable.c, which was
already a home for miscellaneous GUC hook functions.
To avoid cluttering a lot more header files with #include "guc.h",
I also invented a new header file utils/guc_hooks.h and put all
the GUC hook functions' declarations there, regardless of their
originating module. That allowed removal of #include "guc.h"
from some existing headers. The fallout from that (hopefully
all caught here) demonstrates clearly why such inclusions are
best minimized: there are a lot of files that, for example,
were getting array.h at two or more levels of remove, despite
not having any connection at all to GUCs in themselves.
There is some very minor code beautification here, such as
renaming a couple of inconsistently-named hook functions
and improving some comments. But mostly this just moves
code from point A to point B and deals with the ensuing
needs for #include adjustments and exporting a few functions
that previously weren't exported.
Patch by me, per a suggestion from Andres Freund; thanks also
to Michael Paquier for the idea to invent guc_funcs.c.
Discussion: https://postgr.es/m/587607.1662836699@sss.pgh.pa.us
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 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
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
Here we add code which detects when ExecFindPartition() continually finds
the same partition and add a caching layer to improve partition lookup
performance for such cases.
Both RANGE and LIST partitioned tables traditionally require a binary
search for the set of Datums that a partition needs to be found for. This
binary search is commonly visible in profiles when bulk loading into a
partitioned table. Here we aim to reduce the overhead of bulk-loading
into partitioned tables for cases where many consecutive tuples belong to
the same partition and make the performance of this operation closer to
what it is with a traditional non-partitioned table.
When we find the same partition 16 times in a row, the next search will
result in us simply just checking if the current set of values belongs to
the last found partition. For LIST partitioning we record the index into
the PartitionBoundInfo's datum array. This allows us to check if the
current Datum is the same as the Datum that was last looked up. This
means if any given LIST partition supports storing multiple different
Datum values, then the caching only works when we find the same value as
we did the last time. For RANGE partitioning we simply check if the given
Datums are in the same range as the previously found partition.
We store the details of the cached partition in PartitionDesc (i.e.
relcache) so that the cached values are maintained over multiple
statements.
No caching is done for HASH partitions. The majority of the cost in HASH
partition lookups are in the hashing function(s), which would also have to
be executed if we were to try to do caching for HASH partitioned tables.
Since most of the cost is already incurred, we just don't bother. We also
don't do any caching for LIST partitions when we continually find the
values being looked up belong to the DEFAULT partition. We've no
corresponding index in the PartitionBoundInfo's datum array for this case.
We also don't cache when we find the given values match to a LIST
partitioned table's NULL partition. This is so cheap that there's no
point in doing any caching for this. We also don't cache for a RANGE
partitioned table's DEFAULT partition.
There have been a number of different patches submitted to improve
partition lookups. Hou, Zhijie submitted a patch to detect when the value
belonging to the partition key column(s) were constant and added code to
cache the partition in that case. Amit Langote then implemented an idea
suggested by me to remember the last found partition and start to check if
the current values work for that partition. The final patch here was
written by me and was done by taking many of the ideas I liked from the
patches in the thread and redesigning other aspects.
Discussion: https://postgr.es/m/OS0PR01MB571649B27E912EA6CC4EEF03942D9%40OS0PR01MB5716.jpnprd01.prod.outlook.com
Author: Amit Langote, Hou Zhijie, David Rowley
Reviewed-by: Amit Langote, Hou Zhijie
When checking for interleaved partitions, we mark the partition as
interleaved when;
1. we find an earlier partition index when looping over the
sorted-by-Datum indexes[] array, or;
2. we find that the NULL partition allows some non-NULL Datum value.
In the code, as it was written in db632fbca we'll continue to check for
case 2 when we've already marked the partition as interleaved for case 1.
Here we make it so we don't bother marking the partition as interleaved
for case 2 when it's already been marked due to case 1.
Really all this saves is a useless call to bms_add_member(), but since
this code is new to PG15, it seems worth fixing it now to save anyone the
trouble of complaining at some time in the future. We have the
opportunity to improve this now before PG15 is out. This might ease some
future back-patching pain.
Per report and patch by Zhihong Yu. However, I slightly revised the
comments and altered the bms_add_member() code to match in both locations.
We already know that index is equal to boundinfo->null_index from the if
condition.
Author: Zhihong Yu
Discussion: https://postgr.es/m/CALNJ-vQbZR0pYxz9zQ5bqXVcwtGgNgVupeEpNT65HZ+yWZnc4g@mail.gmail.com
Backpatch-through: 15, same as db632fbca.
* Move the execution pruning initialization steps that are common
between both ExecInitAppend() and ExecInitMergeAppend() into a new
function ExecInitPartitionPruning() defined in execPartition.c.
Those steps include creation of a PartitionPruneState to be used for
all instances of pruning and determining the minimal set of child
subplans that need to be initialized by performing initial pruning if
needed, and finally adjusting the subplan_map arrays in the
PartitionPruneState to reflect the new set of subplans remaining
after initial pruning if it was indeed performed.
ExecCreatePartitionPruneState() is no longer exported out of
execPartition.c and has been renamed to CreatePartitionPruneState()
as a local sub-routine of ExecInitPartitionPruning().
* Likewise, ExecFindInitialMatchingSubPlans() that was in charge of
performing initial pruning no longer needs to be exported. In fact,
since it would now have the same body as the more generally named
ExecFindMatchingSubPlans(), except differing in the value of
initial_prune passed to the common subroutine
find_matching_subplans_recurse(), it seems better to remove it and add
an initial_prune argument to ExecFindMatchingSubPlans().
* Add an ExprContext field to PartitionPruneContext to remove the
implicit assumption in the runtime pruning code that the ExprContext to
use to compute pruning expressions that need one can always rely on the
PlanState providing it. A future patch will allow runtime pruning (at
least the initial pruning steps) to be performed without the
corresponding PlanState yet having been created, so this will help.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqEYCpEqh2LMDOp9mT+4-QoVe8HgFMKBjntEMCTZLpcCCA@mail.gmail.com
"const foo *" is quite different from "foo * const".
This code was evidently trying to avoid casting away
const from the arguments, but entirely failed to do so.
Per study of some buildfarm warnings from anole
(which unfortunately are mostly ignorable, since it
seems not to understand "restrict" very well).
I'm surprised though that nothing else has complained.
This field was recently added in db632fbca, however that commit missed one
place where it should have initialized the new field to NULL. The missed
location is where the PartitionBoundInfo is created for partition-wise
join relations. Technically there could be interleaved partitions in a
partition-wise join relation, but currently the only optimization we use
this field for only does so for base rels and other member rels. So just
document that we don't populate this field for join rels.
Reported-by: Amit Langote
Author: Amit Langote, David Rowley
Reviewed-by: Amit Langote, David Rowley
Discussion: https://postgr.es/m/CA+HiwqE76Rps24kwHsd2Cr82Ua07tJC9t9reG0c7ScX9n_xrEA@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
The error messages using the word "non-negative" are confusing
because it's ambiguous about whether it accepts zero or not.
This commit improves those error messages by replacing it with
less ambiguous word like "greater than zero" or
"greater than or equal to zero".
Also this commit added the note about the word "non-negative" to
the error message style guide, to help writing the new error messages.
When postgres_fdw option fetch_size was set to zero, previously
the error message "fetch_size requires a non-negative integer value"
was reported. This error message was outright buggy. Therefore
back-patch to all supported versions where such buggy error message
could be thrown.
Reported-by: Hou Zhijie
Author: Bharath Rupireddy
Reviewed-by: Kyotaro Horiguchi, Fujii Masao
Discussion: https://postgr.es/m/OS0PR01MB5716415335A06B489F1B3A8194569@OS0PR01MB5716.jpnprd01.prod.outlook.com
Commit 0563a3a8b changed how partition constraints were generated such
that this function no longer computes the mapping of parent attnos to
child attnos.
This is an external function that extensions could use, so this is
potentially a breaking change. No external callers are known, however,
and this will make it simpler to write such callers in the future.
Author: Hou Zhijie
Reviewed-by: David Rowley, Michael Paquier, Soumyadeep Chakraborty
Discussion: https://www.postgresql.org/message-id/flat/OS0PR01MB5716A75A45BE46101A1B489894379@OS0PR01MB5716.jpnprd01.prod.outlook.com
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
In each of the create_*_bound() functions for LIST, RANGE and HASH
partitioning, there were a large number of palloc calls which could be
reduced down to a much smaller number.
In each of these functions, an array was built so that we could qsort it
before making the PartitionBoundInfo. For LIST and HASH partitioning, an
array of pointers was allocated then each element was allocated within
that array. Since the number of items of each dimension is known
beforehand, we can just allocate a single chunk of memory for this.
Similarly, with all partition strategies, we're able to reduce the number
of allocations to build the ->datums field. This is an array of Datum
pointers, but there's no need for the Datums that each element points to
to be singly allocated. One big chunk will do. For RANGE partitioning,
the PartitionBoundInfo->kind field can get the same treatment.
We can apply the same optimizations to partition_bounds_copy(). Doing
this might have a small effect on cache performance when searching for the
correct partition during partition pruning or DML on a partitioned table.
However, that's likely to be small and this is mostly about reducing
palloc overhead.
Author: Nitin Jadhav, Justin Pryzby, David Rowley
Reviewed-by: Justin Pryzby, Zhihong Yu
Discussion: https://postgr.es/m/flat/CAMm1aWYFTqEio3bURzZh47jveiHRwgQTiSDvBORczNEz2duZ1Q@mail.gmail.com
Commit efbfb6424 added logic for reporting exactly which existing
partition conflicts when complaining that a new hash partition's
modulus isn't compatible with the existing ones. However, it
misunderstood the partitioning data structure, and would select
the wrong partition in some cases, or crash outright due to fetching
a bogus table OID in other cases.
Per bug #17076 from Alexander Lakhin. Fix by Amit Langote;
some further work on the code comments by me.
Discussion: https://postgr.es/m/17076-89a16ae835d329b9@postgresql.org
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.
In d6b8d29419 I (Álvaro) was sloppy about recording whether a
partition descripor does or does not include detached partitions, when
the snapshot checking does not see the pg_inherits row marked detached.
In that case no partition was omitted, yet in the relcache entry we were
saving the partdesc as omitting partitions. Flip that (so we save it as
a partdesc not omitting partitions, which indeed it doesn't), which
hopefully makes the code easier to reason about.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqE7GxGU4VdzwZzfiz+Ont5SsopoFkgtrZGEdPqWRL+biA@mail.gmail.com
Makes partition descriptor acquisition faster during the transient
period in which a partition is in the process of being detached.
This also adds the restriction that only one partition can be in
pending-detach state for a partitioned table.
While at it, return find_inheritance_children() API to what it was
before 71f4c8c6f7, and create a separate
find_inheritance_children_extended() that returns detailed info about
detached partitions.
(This incidentally fixes a bug in 8aba932251 whereby a memory context
holding a transient partdesc is reparented to a NULL PortalContext,
leading to permanent leak of that memory. The fix is to no longer rely
on reparenting contexts to PortalContext. Reported by Amit Langote.)
Per gripe from Amit Langote
Discussion: https://postgr.es/m/CA+HiwqFgpP1LxJZOBYGt9rpvTjXXkg5qG2+Xch2Z1Q7KrqZR1A@mail.gmail.com
Have interested callers of find_inheritance_children set the
detached_exist value to false prior to calling it, so that that routine
only has to set it true in the rare cases where it is necessary. Don't
touch it otherwise.
Per buildfarm member thorntail (which reported a UBSan failure here).
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
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
There was some code in gen_prune_steps_from_opexps that needlessly
checked a list was not empty when it clearly had to contain at least one
item. This prompted a further cleanup operation in partprune.c.
Additionally, the previous code could end up adding additional needless
INTERSECT steps. However, those do not appear to be able to cause any
misbehavior.
gen_prune_steps_from_opexps is now no longer in charge of generating
combine pruning steps. Instead, gen_partprune_steps_internal, which
already does some combine step creation has been given the sole
responsibility of generating all combine steps. This means that when
we recursively call gen_partprune_steps_internal, since it always now adds
a combine step when it produces multiple steps, we can just pay attention
to the final step returned.
In passing, do quite a bit of work on the comments to try to more clearly
explain the role of both gen_partprune_steps_internal and
gen_prune_steps_from_opexps. This is fairly complex code so some extra
effort to give any new readers an overview of how things work seems like
a good idea.
Author: Amit Langote
Reported-by: Andy Fan
Reviewed-by: Kyotaro Horiguchi, Andy Fan, Ryan Lambert, David Rowley
Discussion: https://postgr.es/m/CAKU4AWqWoVii+bRTeBQmeVW+PznkdO8DfbwqNsu9Gj4ubt9A6w@mail.gmail.com
Allow a partition be detached from its partitioned table without
blocking concurrent queries, by running in two transactions and only
requiring ShareUpdateExclusive in the partitioned table.
Because it runs in two transactions, it cannot be used in a transaction
block. This is the main reason to use dedicated syntax: so that users
can choose to use the original mode if they need it. But also, it
doesn't work when a default partition exists (because an exclusive lock
would still need to be obtained on it, in order to change its partition
constraint.)
In case the second transaction is cancelled or a crash occurs, there's
ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final
steps.
The main trick to make this work is the addition of column
pg_inherits.inhdetachpending, initially false; can only be set true in
the first part of this command. Once that is committed, concurrent
transactions that use a PartitionDirectory will include or ignore
partitions so marked: in optimizer they are ignored if the row is marked
committed for the snapshot; in executor they are always included. As a
result, and because of the way PartitionDirectory caches partition
descriptors, queries that were planned before the detach will see the
rows in the detached partition and queries that are planned after the
detach, won't.
A CHECK constraint is created that duplicates the partition constraint.
This is probably not strictly necessary, and some users will prefer to
remove it afterwards, but if the partition is re-attached to a
partitioned table, the constraint needn't be rechecked.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
For the error message "every hash partition modulus must be a factor
of the next larger modulus", add a detail message that shows the
particular numbers and existing partition involved. Also comment the
code more.
Reviewed-by: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://www.postgresql.org/message-id/flat/bb9d60b4-aadb-607a-1a9d-fdc3434dddcd%40enterprisedb.com
It turns out that the calculation of [Merge]AppendPath.partitioned_rels
in allpaths.c is faulty and sometimes omits relevant non-leaf partitions,
allowing an assertion added by commit a929e17e5a to trigger. Rather
than fix that, it seems better to get rid of those fields altogether.
We don't really need the info until create_plan time, and calculating
it once for the selected plan should be cheaper than calculating it
for each append path we consider.
The preceding two commits did away with all use of the partitioned_rels
values; this commit just mechanically removes the fields and the code
that calculated them.
Discussion: https://postgr.es/m/87sg8tqhsl.fsf@aurora.ydns.eu
Discussion: https://postgr.es/m/CAJKUy5gCXDSmFs2c=R+VGgn7FiYcLCsEFEuDNNLGfoha=pBE_g@mail.gmail.com
It turns out that the calculation of [Merge]AppendPath.partitioned_rels
in allpaths.c is faulty and sometimes omits relevant non-leaf partitions,
allowing an assertion added by commit a929e17e5a to trigger. Rather
than fix that, it seems better to get rid of those fields altogether.
We don't really need the info until create_plan time, and calculating
it once for the selected plan should be cheaper than calculating it
for each append path we consider.
As a first step, teach make_partition_pruneinfo to collect the relevant
partitioned tables for itself. It's not hard to do so by traversing
from child tables up to parents using the AppendRelInfo links.
While here, make some minor stylistic improvements; mainly, don't use
the "Relids" alias for bitmapsets that are not identities of any
relation considered by the planner. Try to document the logic better,
too.
No backpatch, as there does not seem to be a live problem before
a929e17e5a. Also no new regression test; the code where the bug
was will be gone at the end of this patch series, so it seems a
bit pointless to memorialize the issue.
Tom Lane and David Rowley, per reports from Andreas Seltenreich
and Jaime Casanova.
Discussion: https://postgr.es/m/87sg8tqhsl.fsf@aurora.ydns.eu
Discussion: https://postgr.es/m/CAJKUy5gCXDSmFs2c=R+VGgn7FiYcLCsEFEuDNNLGfoha=pBE_g@mail.gmail.com
perform_pruning_combine_step() was not taught about the number of
partition indexes used in hash partitioning; more embarrassingly,
get_matching_hash_bounds() also had it wrong. These errors are masked
in the common case where all the partitions have the same modulus
and no partition is missing. However, with missing or unequal-size
partitions, we could erroneously prune some partitions that need
to be scanned, leading to silently wrong query answers.
While a minimal-footprint fix for this could be to export
get_partition_bound_num_indexes and make the incorrect functions use it,
I'm of the opinion that that function should never have existed in the
first place. It's not reasonable data structure design that
PartitionBoundInfoData lacks any explicit record of the length of
its indexes[] array. Perhaps that was all right when it could always
be assumed equal to ndatums, but something should have been done about
it as soon as that stopped being true. Putting in an explicit
"nindexes" field makes both partition_bounds_equal() and
partition_bounds_copy() simpler, safer, and faster than before,
and removes explicit knowledge of the number-of-partition-indexes
rules from some other places too.
This change also makes get_hash_partition_greatest_modulus obsolete.
I left that in place in case any external code uses it, but no core
code does anymore.
Per bug #16840 from Michał Albrycht. Back-patch to v11 where the
hash partitioning code came in. (In the back branches, add the new
field at the end of PartitionBoundInfoData to minimize ABI risks.)
Discussion: https://postgr.es/m/16840-571a22976f829ad4@postgresql.org
Invent a new flag bit HASH_STRINGS to specify C-string hashing, which
was formerly the default; and add assertions insisting that exactly
one of the bits HASH_STRINGS, HASH_BLOBS, and HASH_FUNCTION be set.
This is in hopes of preventing recurrences of the type of oversight
fixed in commit a1b8aa1e4 (i.e., mistakenly omitting HASH_BLOBS).
Also, when HASH_STRINGS is specified, insist that the keysize be
more than 8 bytes. This is a heuristic, but it should catch
accidental use of HASH_STRINGS for integer or pointer keys.
(Nearly all existing use-cases set the keysize to NAMEDATALEN or
more, so there's little reason to think this restriction should
be problematic.)
Tweak hash_create() to insist that the HASH_ELEM flag be set, and
remove the defaults it had for keysize and entrysize. Since those
defaults were undocumented and basically useless, no callers
omitted HASH_ELEM anyway.
Also, remove memset's zeroing the HASHCTL parameter struct from
those callers that had one. This has never been really necessary,
and while it wasn't a bad coding convention it was confusing that
some callers did it and some did not. We might as well save a few
cycles by standardizing on "not".
Also improve the documentation for hash_create().
In passing, improve reinit.c's usage of a hash table by storing
the key as a binary Oid rather than a string; and, since that's
a temporary hash table, allocate it in CurrentMemoryContext for
neatness.
Discussion: https://postgr.es/m/590625.1607878171@sss.pgh.pa.us
Michael Paquier
David Rowley
Daniel Gustafsson
Peter Eisentraut
Bruce Momjian
Andrew Dunstan
Alvaro Herrera
Andres Freund
Peter Geoghegan
Tom Lane
Fujii Masao
John Naylor