Blind attempt at fixing ia64, hppa an sparc builds.
The serialized representation of MCV lists did not enforce proper memory
alignment for internal fields, resulting in deserialization issues on
platforms that are more sensitive to this (ia64, sparc and hppa).
This forces a catalog version bump, because the layout of serialized
pg_mcv_list changes.
Broken since 7300a699.
Especially, warn about the hazards of mishandling the backup_label
file. Adjust a couple of server messages to be more clear about
the hazards associated with removing backup_label files, too.
David Steele and Robert Haas, reviewed by Laurenz Albe, Martín
Marqués, Peter Eisentraut, and Magnus Hagander.
Discussion: http://postgr.es/m/7d85c387-000e-16f0-e00b-50bf83c22127@pgmasters.net
The previous code was adding pointers to transient variables to a
list, but by the time the list was read, the variable might be gone,
depending on the compiler. Fix it by making copies in the proper
memory context.
This adds the CONCURRENTLY option to the REINDEX command. A REINDEX
CONCURRENTLY on a specific index creates a new index (like CREATE
INDEX CONCURRENTLY), then renames the old index away and the new index
in place and adjusts the dependencies, and then drops the old
index (like DROP INDEX CONCURRENTLY). The REINDEX command also has
the capability to run its other variants (TABLE, DATABASE) with the
CONCURRENTLY option (but not SYSTEM).
The reindexdb command gets the --concurrently option.
Author: Michael Paquier, Andreas Karlsson, Peter Eisentraut
Reviewed-by: Andres Freund, Fujii Masao, Jim Nasby, Sergei Kornilov
Discussion: https://www.postgresql.org/message-id/flat/60052986-956b-4478-45ed-8bd119e9b9cf%402ndquadrant.com#74948a1044c56c5e817a5050f554ddee
This moves the responsibility for:
- creating the storage necessary for a relation, including creating a
new relfilenode for a relation with existing storage
- non-transactional truncation of a relation
- VACUUM FULL / CLUSTER's rewrite of a table
below tableam.
This is fairly straight forward, with a bit of complexity smattered in
to move the computation of xid / multixid horizons below the AM, as
they don't make sense for every table AM.
Author: Andres Freund
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
There were multiple issues in deserialization of pg_mcv_list values.
Firstly, the data is loaded from syscache, but the deserialization was
performed after ReleaseSysCache(), at which point the data might have
already disappeared. Fixed by moving the calls in statext_mcv_load,
and using the same NULL-handling code as existing stats.
Secondly, the deserialized representation used pointers into the
serialized representation. But that is also unsafe, because the data
may disappear at any time. Fixed by reworking and simplifying the
deserialization code to always copy all the data.
And thirdly, when deserializing values for types passed by value, the
code simply did memcpy(d,s,typlen) which however does not work on
bigendian machines. Fixed by using fetch_att/store_att_byval.
Provide GetTopFullTransactionId() and GetCurrentFullTransactionId().
The intended users of these interfaces are access methods that use
xids for visibility checks but don't want to have to go back and
"freeze" existing references some time later before the 32 bit xid
counter wraps around.
Use a new struct to serialize the transaction state for parallel
query, because FullTransactionId doesn't fit into the previous
serialization scheme very well.
Author: Thomas Munro
Reviewed-by: Heikki Linnakangas
Discussion: https://postgr.es/m/CAA4eK1%2BMv%2Bmb0HFfWM9Srtc6MVe160WFurXV68iAFMcagRZ0dQ%40mail.gmail.com
Instead of inferring epoch progress from xids and checkpoints,
introduce a 64 bit FullTransactionId type and use it to track xid
generation. This fixes an unlikely bug where the epoch is reported
incorrectly if the range of active xids wraps around more than once
between checkpoints.
The only user-visible effect of this commit is to correct the epoch
used by txid_current() and txid_status(), also visible with
pg_controldata, in those rare circumstances. It also creates some
basic infrastructure so that later patches can use 64 bit
transaction IDs in more places.
The new type is a struct that we pass by value, as a form of strong
typedef. This prevents the sort of accidental confusion between
TransactionId and FullTransactionId that would be possible if we
were to use a plain old uint64.
Author: Thomas Munro
Reported-by: Amit Kapila
Reviewed-by: Andres Freund, Tom Lane, Heikki Linnakangas
Discussion: https://postgr.es/m/CAA4eK1%2BMv%2Bmb0HFfWM9Srtc6MVe160WFurXV68iAFMcagRZ0dQ%40mail.gmail.com
To support building indexes over tables of different AMs, the scans to
do so need to be routed through the table AM. While moving a fair
amount of code, nearly all the changes are just moving code to below a
callback.
Currently the range based interface wouldn't make much sense for non
block based table AMs. But that seems aceptable for now.
Author: Andres Freund
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
The MCV build should always call get_mincount_for_mcv_list(), as the
there is no other logic to decide whether the MCV list represents all
the data. So just remove the (ngroups > nitems) condition.
Also, when building MCV lists, the number of items was limited by the
statistics target (i.e. up to 10000). But when deserializing the MCV
list, a different value (8192) was used to check the input, causing
an error. Simply ensure that the same value is used in both places.
This should have been included in 7300a69950, but I forgot to include it
in that commit.
Introduce a third extended statistic type, supported by the CREATE
STATISTICS command - MCV lists, a generalization of the statistic
already built and used for individual columns.
Compared to the already supported types (n-distinct coefficients and
functional dependencies), MCV lists are more complex, include column
values and allow estimation of much wider range of common clauses
(equality and inequality conditions, IS NULL, IS NOT NULL etc.).
Similarly to the other types, a new pseudo-type (pg_mcv_list) is used.
Author: Tomas Vondra
Reviewed-by: Dean Rasheed, David Rowley, Mark Dilger, Alvaro Herrera
Discussion: https://postgr.es/m/dfdac334-9cf2-2597-fb27-f0fb3753f435@2ndquadrant.com
In the dim past, the planner kept the fully-processed version of the query
targetlist (the result of preprocess_targetlist) in grouping_planner's
local variable "tlist", and only grudgingly passed it to individual other
routines as needed. Later we discovered a need to still have it available
after grouping_planner finishes, and invented the root->processed_tlist
field for that purpose, but it wasn't used internally to grouping_planner;
the tlist was still being passed around separately in the same places as
before.
Now comes a proposed patch to allow appendrel expansion to add entries
to the processed tlist, well after preprocess_targetlist has finished
its work. To avoid having to pass around the tlist explicitly, it's
proposed to allow appendrel expansion to modify root->processed_tlist.
That makes aliasing the tlist with assorted parameters and local
variables really scary. It would accidentally work as long as the
tlist is initially nonempty, because then the List header won't move
around, but it's not exactly hard to think of ways for that to break.
Aliased values are poor programming practice anyway.
Hence, get rid of local variables and parameters that can be identified
with root->processed_tlist, in favor of just using that field directly.
And adjust comments to match. (Some of the new comments speak as though
it's already possible for appendrel expansion to modify the tlist; that's
not true yet, but will happen in a later patch.)
Discussion: https://postgr.es/m/9d7c5112-cb99-6a47-d3be-cf1ee6862a1d@lab.ntt.co.jp
Column references are not allowed in default expressions and partition
bound expressions, and are restricted as such once the transformation of
their expressions is done. However, trying to use more complex column
references can lead to confusing error messages. For example, trying to
use a two-field column reference name for default expressions and
partition bounds leads to "missing FROM-clause entry for table", which
makes no sense in their respective context.
In order to make the errors generated more useful, this commit adds more
verbose messages when transforming column references depending on the
context. This has a little consequence though: for example an
expression using an aggregate with a column reference as argument would
cause an error to be generated for the column reference, while the
aggregate was the problem reported before this commit because column
references get transformed first.
The confusion exists for default expressions for a long time, and the
problem is new as of v12 for partition bounds. Still per the lack of
complaints on the matter no backpatch is done.
The patch has been written by Amit Langote and me, and Tom Lane has
provided the improvement of the documentation for default expressions on
the CREATE TABLE page.
Author: Amit Langote, Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20190326020853.GM2558@paquier.xyz
The transaction ID returned by GetNextXidAndEpoch() is in the future,
so we can't attempt to access its status or we might try to read a
CLOG page that doesn't exist. The > vs >= confusion probably stemmed
from the choice of a variable name containing the word "last" instead
of "next", so fix that too.
Back-patch to 10 where the function arrived.
Author: Thomas Munro
Discussion: https://postgr.es/m/CA%2BhUKG%2Buua_BV5cyfsioKVN2d61Lukg28ECsWTXKvh%3DBtN2DPA%40mail.gmail.com
Relations dropped in a single transaction are tracked in a list of
unowned relations. With large number of dropped relations this resulted
in poor performance at the end of a transaction, when the relations are
removed from the singly linked list one by one.
Commit b4166911 attempted to address this issue (particularly when it
happens during recovery) by removing the relations in a reverse order,
resulting in O(1) lookups in the list of unowned relations. This did
not work reliably, though, and it was possible to trigger the O(N^2)
behavior in various ways.
Instead of trying to remove the relations in a specific order with
respect to the linked list, which seems rather fragile, switch to a
regular doubly linked. That allows us to remove relations cheaply no
matter where in the list they are.
As b4166911 was a bugfix, backpatched to all supported versions, do the
same thing here.
Reviewed-by: Alvaro Herrera
Discussion: https://www.postgresql.org/message-id/flat/80c27103-99e4-1d0c-642c-d9f3b94aaa0a%402ndquadrant.com
Backpatch-through: 9.4
Previously the xid horizon was only computed during WAL replay. That
had two major problems:
1) It relied on knowing what the table pointed to looks like. That was
easy enough before the introducing of tableam (we knew it had to be
heap, although some trickery around logging the heap relfilenodes
was required). But to properly handle table AMs we need
per-database catalog access to look up the AM handler, which
recovery doesn't allow.
2) Not knowing the xid horizon also makes it hard to support logical
decoding on standbys. When on a catalog table, we need to be able
to conflict with slots that have an xid horizon that's too old. But
computing the horizon by visiting the heap only works once
consistency is reached, but we always need to be able to detect
conflicts.
There's also a secondary problem, in that the current method performs
redundant work on every standby. But that's counterbalanced by
potentially computing the value when not necessary (either because
there's no standby, or because there's no connected backends).
Solve 1) and 2) by moving computation of the xid horizon to the
primary and by involving tableam in the computation of the horizon.
To address the potentially increased overhead, increase the efficiency
of the xid horizon computation for heap by sorting the tids, and
eliminating redundant buffer accesses. When prefetching is available,
additionally perform prefetching of buffers. As this is more of a
maintenance task, rather than something routinely done in every read
only query, we add an arbitrary 10 to the effective concurrency -
thereby using IO concurrency, when not globally enabled. That's
possibly not the perfect formula, but seems good enough for now.
Bumps WAL format, as latestRemovedXid is now part of the records, and
the heap's relfilenode isn't anymore.
Author: Andres Freund, Amit Khandekar, Robert Haas
Reviewed-By: Robert Haas
Discussion:
https://postgr.es/m/20181212204154.nsxf3gzqv3gesl32@alap3.anarazel.dehttps://postgr.es/m/20181214014235.dal5ogljs3bmlq44@alap3.anarazel.dehttps://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
ALTER INDEX .. ATTACH PARTITION fails if the partitioned table where the
index is defined contains more dropped columns than its partition, with
this message:
ERROR: incorrect attribute map
The cause was that one caller of CompareIndexInfo was passing the number
of attributes of the partition rather than the parent, which confused
the length check. Repair.
This can cause pg_upgrade to fail when used on such a database. Leave
some more objects around after regression tests, so that the case is
detected by pg_upgrade test suite.
Remove some spurious empty lines noticed while looking for other cases
of the same problem.
Discussion: https://postgr.es/m/20190326213924.GA2322@alvherre.pgsql
Up to now, otherrel RelOptInfos were built at the same time as baserel
RelOptInfos, thanks to recursion in build_simple_rel(). However,
nothing in query_planner's preprocessing cares at all about otherrels,
only baserels, so we don't really need to build them until just before
we enter make_one_rel. This has two benefits:
* create_lateral_join_info did a lot of extra work to propagate
lateral-reference information from parents to the correct children.
But if we delay creation of the children till after that, it's
trivial (and much harder to break, too).
* Since we have all the restriction quals correctly assigned to
parent appendrels by this point, it'll be possible to do plan-time
pruning and never make child RelOptInfos at all for partitions that
can be pruned away. That's not done here, but will be later on.
Amit Langote, reviewed at various times by Dilip Kumar, Jesper Pedersen,
Yoshikazu Imai, and David Rowley
Discussion: https://postgr.es/m/9d7c5112-cb99-6a47-d3be-cf1ee6862a1d@lab.ntt.co.jp
Commit caf626b2c missed that the relevant reloptions entry needs
to be moved from the intRelOpts[] array to realRelOpts[].
Somewhat surprisingly, it seems to work anyway, perhaps because
the desired default and limit values are all integers. We ought
to have either a simpler data structure or better cross-checking
here, but that's for another patch.
Nikolay Shaplov
Discussion: https://postgr.es/m/4861742.12LTaSB3sv@x200m
We've been creating duplicate RTEs for partitioned tables just
because we do so for regular inheritance parent tables. But unlike
regular-inheritance parents which are themselves regular tables
and thus need to be scanned, partitioned tables don't need the
extra RTE.
This makes the conditions for building a child RTE the same as those
for building an AppendRelInfo, allowing minor simplification in
expand_single_inheritance_child. Since the planner's actual processing
is driven off the AppendRelInfo list, nothing much changes beyond that,
we just have one fewer useless RTE entry.
Amit Langote, reviewed and hacked a bit by me
Discussion: https://postgr.es/m/9d7c5112-cb99-6a47-d3be-cf1ee6862a1d@lab.ntt.co.jp
These instances were apparently trying to carry the const qualifier
from the arguments through the complex casts, but for that the const
qualifier was misplaced.
After 71bdc99d0d, "tableam: Add helper for indexes to check if a
corresponding table tuples exist." there's no in-core user left. As
there's unlikely to be an external user, and such an external user
could easily be adjusted to use table_index_fetch_tuple_check(),
remove heap_hot_search().
Per complaint from Peter Geoghegan
Author: Andres Freund
Discussion: https://postgr.es/m/CAH2-Wzn0Oq4ftJrTqRAsWy2WGjv0QrJcwoZ+yqWsF_Z5vjUBFw@mail.gmail.com
Since 7c079d7, partition bounds are able to use generalized expression
syntax when processed, treating "minvalue" and "maxvalue" as specific
cases as they get passed down for transformation as a column references.
The checks for infinite bounds in range expressions have been lax
though, causing crashes when trying to use column reference names with
more than one field. Here is an example causing a crash:
CREATE TABLE list_parted (a int) PARTITION BY LIST (a);
CREATE TABLE part_list_crash PARTITION OF list_parted
FOR VALUES IN (somename.somename);
Note that the creation of the second relation should fail as partition
bounds cannot have column references in their expressions, so when
finding an expression which does not match the expected infinite bounds,
then this commit lets the generic transformation machinery check after
it. The error message generated in this case references as well a
missing RTE, which is confusing. This problem will be treated
separately as it impacts as well default expressions for some time, and
for now only the cases where a crash can happen are fixed.
While on it, extend the set of regression tests in place for list
partition bounds and add an extra set for range partition bounds.
Reported-by: Alexander Lakhin
Author: Michael Paquier
Reviewed-by: Amit Langote
Discussion: https://postgr.es/m/15668-0377b1981aa1a393@postgresql.org
This primarily is to allow WHERE CURRENT OF to continue to work as it
currently does. It's not clear to me that these semantics make sense
for every AM, but it works for the in-core heap, and the out of core
zheap. We can refine it further at a later point if necessary.
Author: Andres Freund
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
We were getting just DEFAULT_INEQ_SEL for comparisons such as
"ctid >= constant", but it's possible to do a lot better if we don't
mind some assumptions about the table's tuple density being reasonably
uniform. There are already assumptions much like that elsewhere in
the planner, so that hardly seems like much of an objection.
Extracted from a patch set that also proposes to introduce a special
executor node type for such queries. Not sure if that's going to make
it into v12, but improving the selectivity estimate is useful
independently of that.
Edmund Horner, reviewed by David Rowley
Discussion: https://postgr.es/m/CAMyN-kB-nFTkF=VA_JPwFNo08S0d-Yk0F741S2B7LDmYAi8eyA@mail.gmail.com
If there's only one child relation, the Append or MergeAppend isn't
doing anything useful, and can be elided. It does have a purpose
during planning though, which is to serve as a buffer between parent
and child Var numbering. Therefore we keep it all the way through
to setrefs.c, and get rid of it only after fixing references in the
plan level(s) above it. This works largely the same as setrefs.c's
ancient hack to get rid of no-op SubqueryScan nodes, and can even
share some code with that.
Note the change to make setrefs.c use apply_tlist_labeling rather than
ad-hoc code. This has the effect of propagating the child's resjunk
and ressortgroupref labels, which formerly weren't propagated when
removing a SubqueryScan. Doing that is demonstrably necessary for
the [Merge]Append cases, and seems harmless for SubqueryScan, if only
because trivial_subqueryscan is afraid to collapse cases where the
resjunk marking differs. (I suspect that restriction could now be
removed, though it's unclear that it'd make any new matches possible,
since the outer query can't have references to a child resjunk column.)
David Rowley, reviewed by Alvaro Herrera and Tomas Vondra
Discussion: https://postgr.es/m/CAKJS1f_7u8ATyJ1JGTMHFoKDvZdeF-iEBhs+sM_SXowOr9cArg@mail.gmail.com
Add additional heuristics to the algorithm for locating an optimal split
location. New logic identifies localized monotonically increasing
values in indexes with multiple columns. When this insertion pattern is
detected, page splits split just after the new item that provoked a page
split (or apply leaf fillfactor in the style of a rightmost page split).
This optimization is a variation of the long established leaf fillfactor
optimization used during rightmost page splits.
50/50 page splits are only appropriate with a pattern of truly random
insertions, where the average space utilization ends up at 65% - 70%.
Without this patch, affected cases have leaf pages that are no more than
about 50% full on average. Future insertions can never make use of the
free space left behind. With this patch, affected cases have leaf pages
that are about 90% full on average (assuming a fillfactor of 90).
Localized monotonically increasing insertion patterns are presumed to be
fairly common in real-world applications. There is a fair amount of
anecdotal evidence for this. Both pg_depend system catalog indexes
(pg_depend_depender_index and pg_depend_reference_index) are at least
20% smaller after the regression tests are run when the optimization is
available. Furthermore, many of the indexes created by a fair use
implementation of TPC-C for Postgres are consistently about 40% smaller
when the optimization is available.
Note that even pg_upgrade'd v3 indexes make use of this optimization.
Author: Peter Geoghegan
Reviewed-By: Heikki Linnakangas
Discussion: https://postgr.es/m/CAH2-WzkpKeZJrXvR_p7VSY1b-s85E3gHyTbZQzR0BkJ5LrWF_A@mail.gmail.com
This uses the same progress reporting infrastructure added in commit
c16dc1aca5 and extends it to these
additional cases. We lack the ability to track the internal progress
of sorts and index builds so the information reported is
coarse-grained for some parts of the operation, but it still seems
like a significant improvement over having nothing at all.
Tatsuro Yamada, reviewed by Thomas Munro, Masahiko Sawada, Michael
Paquier, Jeff Janes, Alvaro Herrera, Rafia Sabih, and by me. A fair
amount of polishing also by me.
Discussion: http://postgr.es/m/59A77072.3090401@lab.ntt.co.jp
Non-backtracking flex parsers work faster than backtracking ones. So, this
commit gets rid of backtracking in jsonpath_scan.l. That required explicit
handling of some cases as well as manual backtracking for some cases. More
regression tests for numerics are added.
Discussion: https://mail.google.com/mail/u/0?ik=a20b091faa&view=om&permmsgid=msg-f%3A1628425344167939063
Author: John Naylor, Nikita Gluknov, Alexander Korotkov
This commit include formatting improvements, renamings and comments. Also,
it makes jsonpath_scan.l be more uniform with other our lexers. Firstly,
states names are renamed to more short alternatives. Secondly, <INITIAL>
prefix removed from the rules. Corresponding rules are moved to the tail, so
they would anyway work only in initial state.
Author: Alexander Korotkov
Reviewed-by: John Naylor
Coverity complained that simple8b_encode() might read beyond the end of
the 'diffs' array, in the loop to encode the integers. That was a false
positive, because we never get into the loop in modes 0 or 1, and the
array is large enough for all the other modes. But I admit it's very
subtle, so it's not surprising that Coverity didn't see it, and it's not
very obvious to humans either. Refactor it, so that the second loop
re-computes the differences, instead of carrying them over from the first
loop in the 'diffs' array. This way, the 'diffs' array is not needed
anymore. It makes no measurable difference in performance, and seems more
straightforward this way.
Also, improve the comments in simple8b_encode(): fix the comment about its
return value that was flat-out wrong, and explain the condition when it
returns EMPTY_CODEWORD better.
In the passing, move the 'selector' from the codeword's low bits to the
high bits. It doesn't matter much, but looking at the original paper, and
googling around for other Simple-8b implementations, that's how it's
usually done.
Per Coverity, and Tom Lane's report off-list.
This is essentially the tableam version of heapam_fetch(),
i.e. fetching a tuple identified by a tid, performing visibility
checks.
Note that this different from table_index_fetch_tuple(), which is for
index lookups. It therefore has to handle a tid pointing to an earlier
version of a tuple if the AM uses an optimization like heap's HOT. Add
comments to that end.
This commit removes the stats_relation argument from heap_fetch, as
it's been unused for a long time.
Author: Andres Freund
Reviewed-By: Haribabu Kommi
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
Previously those directly performed a heap_insert(). Use
table_insert() instead. The input slot of those routines is not of
the target relation - we could fix that by copying if necessary, but
that'd not be beneficial for performance. As those codepaths don't
access any AM specific tuple fields (say xmin/xmax), there's no need
to use an AM specific slot.
Author: Andres Freund
Reviewed-By: Haribabu Kommi
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
Commit 8aa9dd74b didn't quite finish the job in this area after all,
because DROP ROLE has a code path distinct from DROP OWNED BY, and
it was still reporting dependent objects in whatever order the index
scan returned them in.
Buildfarm experience shows that index ordering of equal-keyed objects is
significantly less stable than before in the wake of using heap TIDs as
tie-breakers. So if we try to hide the unstable ordering by suppressing
DETAIL reports, we're just going to end up having to do that for every
DROP that reports multiple objects. That's not great from a coverage
or problem-detection standpoint, and it's something we'll inevitably
forget in future patches, leading to more iterations of fixing-an-
unstable-result. So let's just bite the bullet and sort here too.
Discussion: https://postgr.es/m/E1h6eep-0001Mw-Vd@gemulon.postgresql.org
It doesn't make sense to consider the possibility that there will only
be one candidate split point when choosing among split points to find
the split with the lowest penalty. This is a vestige of an earlier
version of the patch that became commit fab25024.
Issue spotted while rereviewing coverage of the nbtree patch series
using gcov.
Since its introduction in 19dc233c, current_logfiles has been assigned
the same permissions as a log file, which can be enforced with
log_file_mode. This setup can lead to incompatibility problems with
group access permissions as current_logfiles is not located in the log
directory, but at the root of the data folder. Hence, if group
permissions are used but log_file_mode is more restrictive, a backup
with a user in the group having read access could fail even if the log
directory is located outside of the data folder.
Per discussion with the folks mentioned below, we have concluded that
current_logfiles should not be treated as a log file as it only stores
metadata related to log files, and that it should use the same
permissions as all other files in the data directory. This solution has
the merit to be simple and fixes all the interaction problems between
group access and log_file_mode.
Author: Haribabu Kommi
Reviewed-by: Stephen Frost, Robert Haas, Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/CAJrrPGcEotF1P7AWoeQyD3Pqr-0xkQg_Herv98DjbaMj+naozw@mail.gmail.com
Backpatch-through: 11, where group access has been added.
Add command variants COMMIT AND CHAIN and ROLLBACK AND CHAIN, which
start new transactions with the same transaction characteristics as the
just finished one, per SQL standard.
Support for transaction chaining in PL/pgSQL is also added. This
functionality is especially useful when running COMMIT in a loop in
PL/pgSQL.
Reviewed-by: Fabien COELHO <coelho@cri.ensmp.fr>
Discussion: https://www.postgresql.org/message-id/flat/28536681-324b-10dc-ade8-ab46f7645a5a@2ndquadrant.com
This adds new, required, table AM callbacks for insert/delete/update
and lock_tuple. To be able to reasonably use those, the EvalPlanQual
mechanism had to be adapted, moving more logic into the AM.
Previously both delete/update/lock call-sites and the EPQ mechanism had
to have awareness of the specific tuple format to be able to fetch the
latest version of a tuple. Obviously that needs to be abstracted
away. To do so, move the logic that find the latest row version into
the AM. lock_tuple has a new flag argument,
TUPLE_LOCK_FLAG_FIND_LAST_VERSION, that forces it to lock the last
version, rather than the current one. It'd have been possible to do
so via a separate callback as well, but finding the last version
usually also necessitates locking the newest version, making it
sensible to combine the two. This replaces the previous use of
EvalPlanQualFetch(). Additionally HeapTupleUpdated, which previously
signaled either a concurrent update or delete, is now split into two,
to avoid callers needing AM specific knowledge to differentiate.
The move of finding the latest row version into tuple_lock means that
encountering a row concurrently moved into another partition will now
raise an error about "tuple to be locked" rather than "tuple to be
updated/deleted" - which is accurate, as that always happens when
locking rows. While possible slightly less helpful for users, it seems
like an acceptable trade-off.
As part of this commit HTSU_Result has been renamed to TM_Result, and
its members been expanded to differentiated between updating and
deleting. HeapUpdateFailureData has been renamed to TM_FailureData.
The interface to speculative insertion is changed so nodeModifyTable.c
does not have to set the speculative token itself anymore. Instead
there's a version of tuple_insert, tuple_insert_speculative, that
performs the speculative insertion (without requiring a flag to signal
that fact), and the speculative insertion is either made permanent
with table_complete_speculative(succeeded = true) or aborted with
succeeded = false).
Note that multi_insert is not yet routed through tableam, nor is
COPY. Changing multi_insert requires changes to copy.c that are large
enough to better be done separately.
Similarly, although simpler, CREATE TABLE AS and CREATE MATERIALIZED
VIEW are also only going to be adjusted in a later commit.
Author: Andres Freund and Haribabu Kommi
Discussion:
https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.dehttps://postgr.es/m/20190313003903.nwvrxi7rw3ywhdel@alap3.anarazel.dehttps://postgr.es/m/20160812231527.GA690404@alvherre.pgsql
Previously we were using the SQL:2003 definition, which doesn't allow
this, but that creates a serious dump/restore gotcha: there is no
setting of xmloption that will allow all valid XML data. Hence,
switch to the 2006 definition.
Since libxml doesn't accept <!DOCTYPE> directives in the mode we
use for CONTENT parsing, the implementation is to detect <!DOCTYPE>
in the input and switch to DOCUMENT parsing mode. This should not
cost much, because <!DOCTYPE> should be close to the front of the
input if it's there at all. It's possible that this causes the
error messages for malformed input to be slightly different than
they were before, if said input includes <!DOCTYPE>; but that does
not seem like a big problem.
In passing, buy back a few cycles in parsing of large XML documents
by not doing strlen() of the whole input in parse_xml_decl().
Back-patch because dump/restore failures are not nice. This change
shouldn't break any cases that worked before, so it seems safe to
back-patch.
Chapman Flack (revised a bit by me)
Discussion: https://postgr.es/m/CAN-V+g-6JqUQEQZ55Q3toXEN6d5Ez5uvzL4VR+8KtvJKj31taw@mail.gmail.com
Teach nbtree forward index scans to check the high key before moving to
the right sibling page in the hope of finding that it isn't actually
necessary to do so. The new check may indicate that the scan definitely
cannot find matching tuples to the right, ending the scan immediately.
We already opportunistically force a similar "continuescan orientated"
key check of the final non-pivot tuple when it's clear that it cannot be
returned to the scan due to being dead-to-all. The new high key check
is complementary.
The new approach for forward scans is more effective than checking the
final non-pivot tuple, especially with composite indexes and non-unique
indexes. The improvements to the logic for picking a split point added
by commit fab25024 make it likely that relatively dissimilar high keys
will appear on a page. A distinguishing key value that can only appear
on non-pivot tuples on the right sibling page will often be present in
leaf page high keys.
Since forcing the final item to be key checked no longer makes any
difference in the case of forward scans, the existing extra key check is
now only used for backwards scans. Backward scans continue to
opportunistically check the final non-pivot tuple, which is actually the
first non-pivot tuple on the page (not the last).
Note that even pg_upgrade'd v3 indexes make use of this optimization.
Author: Peter Geoghegan, Heikki Linnakangas
Reviewed-By: Heikki Linnakangas
Discussion: https://postgr.es/m/CAH2-WzkOmUduME31QnuTFpimejuQoiZ-HOf0pOWeFZNhTMctvA@mail.gmail.com
Tomas Vondra
Andres Freund
Robert Haas
Peter Eisentraut
Thomas Munro
Tom Lane
Michael Paquier
Alvaro Herrera
Peter Geoghegan
Alexander Korotkov
Heikki Linnakangas