They already fail anyway, but prior to this patch they raise an ugly
error message about a lock that cannot be acquired. This just improves
the message.
Author: Masahiko Sawada
Reported-by: Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoBZau4g4_NUf3BKNd=CdYK+xaPdtJCzvOC1TxGdTiJx_Q@mail.gmail.com
Reviewed-by: Kuntal Ghosh, Alexander Korotkov, Simon Riggs, Michaël Paquier, Álvaro Herrera
This bug causes a lseek() failure to be reported as a "could not open"
failure in the error message, muddling bug reports. I introduced this
copy-and-pasteo in commit 78e1220104.
Noticed while reviewing code for bug report #15221, from lily liang. In
version 10 the affected function is only used by multixact.c and
commit_ts, and only in corner-case circumstances, neither of which are
involved in the reported bug (a pg_subtrans failure.)
Author: Álvaro Herrera
Any changes on page should be done in critical section, so move
_bt_upgrademetapage into critical section. Improve comment. Found by Amit
Kapila during post-commit review of 857f9c36.
Author: Amit Kapila
The "l" (ell) width spec means something in the corresponding scanf usage,
but not here. While modern POSIX says that applying "l" to "f" and other
floating format specs is a no-op, SUSv2 says it's undefined. Buildfarm
experience says that some old compilers emit warnings about it, and at
least one old stdio implementation (mingw's "ANSI" option) actually
produces wrong answers and/or crashes.
Discussion: https://postgr.es/m/21670.1526769114@sss.pgh.pa.us
Discussion: https://postgr.es/m/c085e1da-0d64-1c15-242d-c921f32e0d5c@dunslane.net
- Change vacuum_cleanup_index_scale_factor GUC to PGC_USERSET.
vacuum_cleanup_index_scale_factor GUC was defined as PGC_SIGHUP. But this
GUC affects not only autovacuum. So it might be useful to change it from user
session in order to influence manually runned VACUUM.
- Add missing tab-complete support for vacuum_cleanup_index_scale_factor
reloption.
- Fix condition for B-tree index cleanup.
Zero value of vacuum_cleanup_index_scale_factor means that user wants B-tree
index cleanup to be never skipped.
- Documentation and comment improvements
Authors: Justin Pryzby, Alexander Korotkov, Liudmila Mantrova
Reviewed by: all authors and Robert Haas
Discussion: https://www.postgresql.org/message-id/flat/20180502023025.GD7631%40telsasoft.com
If a continuation record is split so that its first half has already been
removed from the master, and is only present in pg_wal, and there is a
recycled WAL segment in the standby server that looks like it would
contain the second half, recovery would get stuck. The code in
XLogPageRead() incorrectly started streaming at the beginning of the
WAL record, even if we had already read the first page.
Backpatch to 9.4. In principle, older versions have the same problem, but
without replication slots, there was no straightforward mechanism to
prevent the master from recycling old WAL that was still needed by standby.
Without such a mechanism, I think it's reasonable to assume that there's
enough slack in how many old segments are kept around to not run into this,
or you have a WAL archive.
Reported by Jonathon Nelson. Analysis and patch by Kyotaro HORIGUCHI, with
some extra comments by me.
Discussion: https://www.postgresql.org/message-id/CACJqAM3xVz0JY1XFDKPP%2BJoJAjoGx%3DGNuOAshEDWCext7BFvCQ%40mail.gmail.com
Dan Wood diagnosed a long-standing problem that pages containing tuples
that are locked by multixacts containing live lockers may spuriously end
up as candidates for getting their all-visible flag set. This has the
long-term effect that multixacts remain unfrozen; this may previously
pass undetected, but since commit XYZ it would be reported as
"ERROR: found multixact 134100944 from before relminmxid 192042633"
because when a later vacuum tries to freeze the page it detects that a
multixact that should have gotten frozen, wasn't.
Dan proposed a (correct) patch that simply sets a variable to its
correct value, after a bogus initialization. But, per discussion, it
seems better coding to avoid the bogus initializations altogether, since
they could give rise to more bugs later. Therefore this fix rewrites
the logic a little bit to avoid depending on the bogus initializations.
This bug was part of a family introduced in 9.6 by commit a892234f830e;
later, commit 38e9f90a22 fixed most of them, but this one was
unnoticed.
Authors: Dan Wood, Pavan Deolasee, Álvaro Herrera
Reviewed-by: Masahiko Sawada, Pavan Deolasee, Álvaro Herrera
Discussion: https://postgr.es/m/84EBAC55-F06D-4FBE-A3F3-8BDA093CE3E3@amazon.com
nbtsort.c does not need to truncate away non-key attributes for the
minimum key of the leftmost page on a level, since this is only used to
build a minus infinity downlink for the level's leftmost page.
Truncating away non-key attributes in advance of truncating away all
attributes in _bt_sortaddtup() does not affect the correctness of CREATE
INDEX, but it is misleading.
Author: Peter Geoghegan
Discussion: https://www.postgresql.org/message-id/CAH2-WzkAS2M3ussHG-s_Av=Zo6dPjOxyu5fNRkYnxQV+YzGQ4w@mail.gmail.com
The principle behind the locking was not very well thought-out, and not
documented. Add a section in the README to explain how it's supposed to
work, and change the code so that it actually works that way.
This fixes two bugs:
1. If fast update was turned on concurrently, subsequent inserts to the
pending list would not conflict with predicate locks that were acquired
earlier, on entry pages. The included 'predicate-gin-fastupdate' test
demonstrates that. To fix, make all scans acquire a predicate lock on
the metapage. That lock represents a scan of the pending list, whether
or not there is a pending list at the moment. Forget about the
optimization to skip locking/checking for locks, when fastupdate=off.
2. If a scan finds no match, it still needs to lock the entry page. The
point of predicate locks is to lock the gabs between values, whether
or not there is a match. The included 'predicate-gin-nomatch' test
tests that case.
In addition to those two bug fixes, this removes some unnecessary locking,
following the principle laid out in the README. Because all items in
a posting tree have the same key value, a lock on the posting tree root is
enough to cover all the items. (With a very large posting tree, it would
possibly be better to lock the posting tree leaf pages instead, so that a
"skip scan" with a query like "A & B", you could avoid unnecessary conflict
if a new tuple is inserted with A but !B. But let's keep this simple.)
Also, some spelling fixes.
Author: Heikki Linnakangas with some editorization by me
Review: Andrey Borodin, Alexander Korotkov
Discussion: https://www.postgresql.org/message-id/0b3ad2c2-2692-62a9-3a04-5724f2af9114@iki.fi
If an interrupt arrives in the middle of FinishPreparedTransaction
and any callback decide to call CHECK_FOR_INTERRUPTS (e.g.
RemoveTwoPhaseFile can write a warning with ereport, which checks for
interrupts) then it's possible to leave current GXact undeleted.
Backpatch to all supported branches
Stas Kelvich
Discussion: ihttps://www.postgresql.org/message-id/3AD85097-A3F3-4EBA-99BD-C38EDF8D2949@postgrespro.ru
Recent gcc can warn about switch-case fall throughs that are not
explicitly labeled as intentional. This seems like a good thing,
so clean up the warnings exposed thereby by labeling all such
cases with comments that gcc will recognize.
In files that already had one or more suitable comments, I generally
matched the existing style of those. Otherwise I went with
/* FALLTHROUGH */, which is one of the spellings approved at the
more-restrictive-than-default level -Wimplicit-fallthrough=4.
(At the default level you can also spell it /* FALL ?THRU */,
and it's not picky about case. What you can't do is include
additional text in the same comment, so some existing comments
containing versions of this aren't good enough.)
Testing with gcc 8.0.1 (Fedora 28's current version), I found that
I also had to put explicit "break"s after elog(ERROR) or ereport(ERROR);
apparently, for this purpose gcc doesn't recognize that those don't
return. That seems like possibly a gcc bug, but it's fine because
in most places we did that anyway; so this amounts to a visit from the
style police.
Discussion: https://postgr.es/m/15083.1525207729@sss.pgh.pa.us
This change makes this module act more like most of our other low-level
resource management modules. It's a caller error if something is not
explicitly closed by the end of a successful transaction, so issue
a WARNING about it. This would not actually have caught the file leak
bug fixed in commit 231bcd080, because that was in a transaction-abort
path; but it still seems like a good, and pretty cheap, cross-check.
Discussion: https://postgr.es/m/152056616579.4966.583293218357089052@wrigleys.postgresql.org
After introducing usage of t_tid of inner or page high key for storing
number of attributes of tuple, validation of tuple's ItemPointer with
ItemPointerIsValid becomes incorrect, it's need to validate only blocknumber of
ItemPointer. Missing this causes a incorrect page deletion, fix that. Test is
added.
BTW, current contrib/amcheck doesn't fail on index corrupted by this way.
Also introduce BTreeTupleGetTopParent/BTreeTupleSetTopParent macroses to improve
code readability and to avoid possible confusion with page high key: high key
is used to store top-parent link for branch to remove.
Bug found by Michael Paquier, but bug doesn't exist in previous versions because
t_tid was set to P_HIKEY.
Author: Teodor Sigaev
Reviewer: Peter Geoghegan
Discussion: https://www.postgresql.org/message-id/flat/20180419052436.GA16000%40paquier.xyz
Remove an obsolete reference to the 'afteritem' argument, which was
removed by commit bc292937. Add a comment that clarifies how
_bt_insertonpg() indirectly handles the insertion of high key items.
Author: Peter Geoghegan
New WAL record XLOG_BTREE_META_CLEANUP introduced in 857f9c36 has no handling
in btree_desc() and btree_identify(). This patch implements corresponding
handling.
Alexander Korotkov
Add several assertions that ensure that we're dealing with a pivot tuple
without non-key attributes where that's expected. Also, remove the
assertion within _bt_isequal(), restoring the v10 function signature. A
similar check will be performed for the page highkey within
_bt_moveright() in most cases. Also avoid dropping all objects within
regression tests, to increase pg_dump test coverage for INCLUDE indexes.
Rather than using infrastructure that's generally intended to be used
with reference counted heap tuple descriptors during truncation, use the
same function that was introduced to store flat TupleDescs in shared
memory (we use a temp palloc'd buffer). This isn't strictly necessary,
but seems more future-proof than the old approach. It also lets us
avoid including rel.h within indextuple.c, which was arguably a
modularity violation. Also, we now call index_deform_tuple() with the
truncated TupleDesc, not the source TupleDesc, since that's more robust,
and saves a few cycles.
In passing, fix a memory leak by pfree'ing truncated pivot tuple memory
during CREATE INDEX. Also pfree during a page split, just to be
consistent.
Refactor _bt_check_natts() to be more readable.
Author: Peter Geoghegan with some editorization by me
Reviewed by: Alexander Korotkov, Teodor Sigaev
Discussion: https://www.postgresql.org/message-id/CAH2-Wz%3DkCWuXeMrBCopC-tFs3FbiVxQNjjgNKdG2sHxZ5k2y3w%40mail.gmail.com
Review of commit 1eb6d652: It's pointless to add padding to the GID fields,
when the code that follows assumes that there is no alignment, and uses
memcpy(). Remove the pointless padding.
Update comments to note the new fields in the WAL records.
Reviewed-by: Michael Paquier
Discussion: https://www.postgresql.org/message-id/33b787bf-dc20-1161-54e9-3f3b607bf59d%40iki.fi
spg_text_leaf_consistent() supposed that it should compare only
Min(querylen, entrylen) bytes of the two strings, and then deal with
any excess bytes in one string or the other by assuming the longer
string is greater if the prefixes are equal. Quite aside from the
fact that that's just wrong in some locales (e.g., 'ch' is not less
than 'd' in cs_CZ), it also risked passing incomplete multibyte
characters to strcoll(), with ensuing bad results.
Instead, just pass the full strings to varstr_cmp, and let it decide
what to do about unequal-length strings.
Fortunately, this error doesn't imply any index corruption, it's just
that searches might return the wrong set of entries.
Per report from Emre Hasegeli, though this is not his patch.
Thanks to Peter Geoghegan for review and discussion.
This code was born broken, so back-patch to all supported branches.
In HEAD, I failed to resist the temptation to do a bit of cosmetic
cleanup/pgindent'ing on 710d90da1, too.
Discussion: https://postgr.es/m/CAE2gYzzb6K51VnTq5i5p52z+j9p2duEa-K1T3RrC_GQEynAKEg@mail.gmail.com
Commit 16828d5c forgot to check that it had a set of missing values
before trying to retrieve a value from it.
An additional query to add coverage for this code is added to the
regression test.
Per bug report from Andreas Seltenreich.
This reverts commits d204ef6377,
83454e3c2b and a few more commits thereafter
(complete list at the end) related to MERGE feature.
While the feature was fully functional, with sufficient test coverage and
necessary documentation, it was felt that some parts of the executor and
parse-analyzer can use a different design and it wasn't possible to do that in
the available time. So it was decided to revert the patch for PG11 and retry
again in the future.
Thanks again to all reviewers and bug reporters.
List of commits reverted, in reverse chronological order:
f1464c5380 Improve parse representation for MERGE
ddb4158579 MERGE syntax diagram correction
530e69e59b Allow cpluspluscheck to pass by renaming variable
01b88b4df5 MERGE minor errata
3af7b2b0d4 MERGE fix variable warning in non-assert builds
a5d86181ec MERGE INSERT allows only one VALUES clause
4b2d44031f MERGE post-commit review
4923550c20 Tab completion for MERGE
aa3faa3c7a WITH support in MERGE
83454e3c2b New files for MERGE
d204ef6377 MERGE SQL Command following SQL:2016
Author: Pavan Deolasee
Reviewed-by: Michael Paquier
The nextOid value is from the start of the checkpoint and may well be stale
compared to values from more recent XLOG_NEXTOID records. Previously, we
adopted it anyway, allowing the OID counter to go backwards during a crash.
While this should be harmless, it contributed to the severity of the bug
fixed in commit 0408e1ed5, by allowing duplicate TOAST OIDs to be assigned
immediately following a crash. Without this error, that issue would only
have arisen when TOAST objects just younger than a multiple of 2^32 OIDs
were deleted and then not vacuumed in time to avoid a conflict.
Pavan Deolasee
Discussion: https://postgr.es/m/CABOikdOgWT2hHkYG3Wwo2cyZJq2zfs1FH0FgX-=h4OLosXHf9w@mail.gmail.com
When selecting a new OID, we take care to avoid picking one that's already
in use in the target table, so as not to create duplicates after the OID
counter has wrapped around. However, up to now we used SnapshotDirty when
scanning for pre-existing entries. That ignores committed-dead rows, so
that we could select an OID matching a deleted-but-not-yet-vacuumed row.
While that mostly worked, it has two problems:
* If recently deleted, the dead row might still be visible to MVCC
snapshots, creating a risk for duplicate OIDs when examining the catalogs
within our own transaction. Such duplication couldn't be visible outside
the object-creating transaction, though, and we've heard few if any field
reports corresponding to such a symptom.
* When selecting a TOAST OID, deleted toast rows definitely *are* visible
to SnapshotToast, and will remain so until vacuumed away. This leads to
a conflict that will manifest in errors like "unexpected chunk number 0
(expected 1) for toast value nnnnn". We've been seeing reports of such
errors from the field for years, but the cause was unclear before.
The fix is simple: just use SnapshotAny to search for conflicting rows.
This results in a slightly longer window before object OIDs can be
recycled, but that seems unlikely to create any large problems.
Pavan Deolasee
Discussion: https://postgr.es/m/CABOikdOgWT2hHkYG3Wwo2cyZJq2zfs1FH0FgX-=h4OLosXHf9w@mail.gmail.com
This optimization was introduced in commit 2b272734. The changes include
some additional comments and documentation, and also these more
substantive changes:
. ensure the optimization is only applied on the leaf node of a tree
whose root is on level 2 or more. It's of little value on small trees.
. Delay calling RelationSetTargetBlock() until after the critical
section of _bt_insertonpg
. ensure the optimization is also applied to unlogged tables.
Pavan Deolasee and Peter Geoghegan with some very light editing from me.
Discussion: https://postgr.es/m/CABOikdO8jhRarNC60nZLktZYhxt+TK8z_V97+Ny499YQdyAfug@mail.gmail.com
The comment earlier in the function correctly states "and the insertion
key is strictly greater than the first key in this page". That is what
we check here, not "greater than or equal".
In commit 9c0a0de4c, I'd failed to notice that catalog/catalog.h
should also be considered a frontend-unsafe header, because it includes
(and needs) the full form of pg_class.h, not to mention relcache.h.
However, various frontend code was depending on it to get
TABLESPACE_VERSION_DIRECTORY, so refactoring of some sort is called for.
The cleanest answer seems to be to move TABLESPACE_VERSION_DIRECTORY,
as well as the OIDCHARS symbol, to common/relpath.h. Do that, and mop up
inclusions as necessary. (I found that quite a few current users of
catalog/catalog.h don't seem to need it at all anymore, apparently as a
result of the refactorings that created common/relpath.[hc]. And
initdb.c needed it only as a route to pg_class_d.h.)
Discussion: https://postgr.es/m/6629.1523294509@sss.pgh.pa.us
This reverts the backend sides of commit 1fde38beaa.
I have, at least for now, left the pg_verify_checksums tool in place, as
this tool can be very valuable without the rest of the patch as well,
and since it's a read-only tool that only runs when the cluster is down
it should be a lot safer.
Consolidate directory and file create permissions for tools which work
with the PG data directory by adding a new module (common/file_perm.c)
that contains variables (pg_file_create_mode, pg_dir_create_mode) and
constants to initialize them (0600 for files and 0700 for directories).
Convert mkdir() calls in the backend to MakePGDirectory() if the
original call used default permissions (always the case for regular PG
directories).
Add tests to make sure permissions in PGDATA are set correctly by the
tools which modify the PG data directory.
Authors: David Steele <david@pgmasters.net>,
Adam Brightwell <adam.brightwell@crunchydata.com>
Reviewed-By: Michael Paquier, with discussion amongst many others.
Discussion: https://postgr.es/m/ad346fe6-b23e-59f1-ecb7-0e08390ad629%40pgmasters.net
When an update moves a row between partitions (supported since
2f17844104), our normal logic for following update chains in READ
COMMITTED mode doesn't work anymore. Cross partition updates are
modeled as an delete from the old and insert into the new
partition. No ctid chain exists across partitions, and there's no
convenient space to introduce that link.
Not throwing an error in a partitioned context when one would have
been thrown without partitioning is obviously problematic. This commit
introduces infrastructure to detect when a tuple has been moved, not
just plainly deleted. That allows to throw an error when encountering
a deletion that's actually a move, while attempting to following a
ctid chain.
The row deleted as part of a cross partition update is marked by
pointing it's t_ctid to an invalid block, instead of self as a normal
update would. That was deemed to be the least invasive and most
future proof way to represent the knowledge, given how few infomask
bits are there to be recycled (there's also some locking issues with
using infomask bits).
External code following ctid chains should be updated to check for
moved tuples. The most likely consequence of not doing so is a missed
error.
Author: Amul Sul, editorialized by me
Reviewed-By: Amit Kapila, Pavan Deolasee, Andres Freund, Robert Haas
Discussion: http://postgr.es/m/CAAJ_b95PkwojoYfz0bzXU8OokcTVGzN6vYGCNVUukeUDrnF3dw@mail.gmail.com
This patch introduces INCLUDE clause to index definition. This clause
specifies a list of columns which will be included as a non-key part in
the index. The INCLUDE columns exist solely to allow more queries to
benefit from index-only scans. Also, such columns don't need to have
appropriate operator classes. Expressions are not supported as INCLUDE
columns since they cannot be used in index-only scans.
Index access methods supporting INCLUDE are indicated by amcaninclude flag
in IndexAmRoutine. For now, only B-tree indexes support INCLUDE clause.
In B-tree indexes INCLUDE columns are truncated from pivot index tuples
(tuples located in non-leaf pages and high keys). Therefore, B-tree indexes
now might have variable number of attributes. This patch also provides
generic facility to support that: pivot tuples contain number of their
attributes in t_tid.ip_posid. Free 13th bit of t_info is used for indicating
that. This facility will simplify further support of index suffix truncation.
The changes of above are backward-compatible, pg_upgrade doesn't need special
handling of B-tree indexes for that.
Bump catalog version
Author: Anastasia Lubennikova with contribition by Alexander Korotkov and me
Reviewed by: Peter Geoghegan, Tomas Vondra, Antonin Houska, Jeff Janes,
David Rowley, Alexander Korotkov
Discussion: https://www.postgresql.org/message-id/flat/56168952.4010101@postgrespro.ru
Add a new WAL record type for TRUNCATE, which is only used when
wal_level >= logical. (For physical replication, TRUNCATE is already
replicated via SMGR records.) Add new callback for logical decoding
output plugins to receive TRUNCATE actions.
Author: Simon Riggs <simon@2ndquadrant.com>
Author: Marco Nenciarini <marco.nenciarini@2ndquadrant.it>
Author: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Reviewed-by: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Hash index searches acquire predicate locks on the primary
page of a bucket. It acquires a lock on both the old and new buckets
for scans that happen concurrently with page splits. During a bucket
split, a predicate lock is copied from the primary page of an old
bucket to the primary page of a new bucket.
Author: Shubham Barai, Amit Kapila
Reviewed by: Amit Kapila, Alexander Korotkov, Thomas Munro
Discussion: https://www.postgresql.org/message-id/flat/CALxAEPvNsM2GTiXdRgaaZ1Pjd1bs+sxfFsf7Ytr+iq+5JJoYXA@mail.gmail.com
This makes it possible to turn checksums on in a live cluster, without
the previous need for dump/reload or logical replication (and to turn it
off).
Enabling checkusm starts a background process in the form of a
launcher/worker combination that goes through the entire database and
recalculates checksums on each and every page. Only when all pages have
been checksummed are they fully enabled in the cluster. Any failure of
the process will revert to checksums off and the process has to be
started.
This adds a new WAL record that indicates the state of checksums, so
the process works across replicated clusters.
Authors: Magnus Hagander and Daniel Gustafsson
Review: Tomas Vondra, Michael Banck, Heikki Linnakangas, Andrey Borodin
THis adds a "flags" field to the BackgroundWorkerInitializeConnection()
and BackgroundWorkerInitializeConnectionByOid(). For now only one flag,
BGWORKER_BYPASS_ALLOWCONN, is defined, which allows the worker to ignore
datallowconn.
857f9c36 bumps B-tree metapage version while upgrade is performed "on the fly"
when needed. However, some asserts fired when old version metapage was
cached to rel->rd_amcache. Despite new metadata fields are never used from
rel->rd_amcache, that needs to be fixed. This patch introduces metadata
upgrade during its caching, which fills unavailable fields with their default
values. contrib/pageinspect is also patched to handle non-upgraded metapages
in the same way.
Author: Alexander Korotkov
BRIN indexes like to propagate additions of free space into the upper pages
of their free space maps as soon as the new space is known, even when it's
just on one individual index page. Previously this required calling
FreeSpaceMapVacuum, which is quite an expensive thing if the map is large.
Use the FreeSpaceMapVacuumRange function recently added by commit c79f6df75
to reduce the amount of work done for this purpose.
Fix a couple of places that neglected to do the upper-page vacuuming at all
after recording new free space. If the policy is to be that BRIN should do
that, it should do it everywhere.
Do RecordPageWithFreeSpace unconditionally in brin_page_cleanup, and do
FreeSpaceMapVacuum unconditionally in brin_vacuum_scan. Because of the
FSM's imprecise storage of free space, the old complications here seldom
bought anything, they just slowed things down. This approach also
provides a predictable path for FSM corruption to be repaired.
Remove premature RecordPageWithFreeSpace call in brin_getinsertbuffer
where it's about to return an extended page to the caller. The caller
should do that, instead, after it's inserted its new tuple. Fix the
one caller that forgot to do so.
Simplify logic in brin_doupdate's same-page-update case by postponing
brin_initialize_empty_new_buffer to after the critical section; I see
little point in doing it before.
Avoid repeat calls of RelationGetNumberOfBlocks in brin_vacuum_scan.
Avoid duplicate BufferGetBlockNumber and BufferGetPage calls in
a couple of places where we already had the right values.
Move a BRIN_elog debug logging call out of a critical section; that's
pretty unsafe and I don't think it buys us anything to not wait till
after the critical section.
Move the "*extended = false" step in brin_getinsertbuffer into the
routine's main loop. There's no actual bug there, since the loop can't
iterate with *extended still true, but it doesn't seem very future-proof
as coded; and it's certainly not documented as a loop invariant.
This is all from follow-on investigation inspired by commit c79f6df75.
Discussion: https://postgr.es/m/5801.1522429460@sss.pgh.pa.us
Vacuum of index consists from two stages: multiple (zero of more) ambulkdelete
calls and one amvacuumcleanup call. When workload on particular table
is append-only, then autovacuum isn't intended to touch this table. However,
user may run vacuum manually in order to fill visibility map and get benefits
of index-only scans. Then ambulkdelete wouldn't be called for indexes
of such table (because no heap tuples were deleted), only amvacuumcleanup would
be called In this case, amvacuumcleanup would perform full index scan for
two objectives: put recyclable pages into free space map and update index
statistics.
This patch allows btvacuumclanup to skip full index scan when two conditions
are satisfied: no pages are going to be put into free space map and index
statistics isn't stalled. In order to check first condition, we store
oldest btpo_xact in the meta-page. When it's precedes RecentGlobalXmin, then
there are some recyclable pages. In order to check second condition we store
number of heap tuples observed during previous full index scan by cleanup.
If fraction of newly inserted tuples is less than
vacuum_cleanup_index_scale_factor, then statistics isn't considered to be
stalled. vacuum_cleanup_index_scale_factor can be defined as both reloption and GUC (default).
This patch bumps B-tree meta-page version. Upgrade of meta-page is performed
"on the fly": during VACUUM meta-page is rewritten with new version. No special
handling in pg_upgrade is required.
Author: Masahiko Sawada, Alexander Korotkov
Review by: Peter Geoghegan, Kyotaro Horiguchi, Alexander Korotkov, Yura Sokolov
Discussion: https://www.postgresql.org/message-id/flat/CAD21AoAX+d2oD_nrd9O2YkpzHaFr=uQeGr9s1rKC3O4ENc568g@mail.gmail.com
The prefix operator along with SP-GiST indexes can be used as an alternative
for LIKE 'word%' commands and it doesn't have a limitation of string/prefix
length as B-Tree has.
Bump catalog version
Author: Ildus Kurbangaliev with some editorization by me
Review by: Arthur Zakirov, Alexander Korotkov, and me
Discussion: https://www.postgresql.org/message-id/flat/20180202180327.222b04b3@wp.localdomain
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 other require multiple PL statements.
e.g.
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 and partitioned tables, including
column and row security enforcement, as well as support for
row, statement and transition triggers.
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 statically from PL/pgSQL.
MERGE does not yet support inheritance, write rules,
RETURNING clauses, updatable views or foreign tables.
MERGE follows SQL Standard per the most recent SQL:2016.
Includes full tests and documentation, including full
isolation tests to demonstrate the concurrent behavior.
This version written from scratch in 2017 by Simon Riggs,
using docs and tests originally written in 2009. Later work
from Pavan Deolasee has been both complex and deep, leaving
the lead author credit now in his hands.
Extensive discussion of concurrency from Peter Geoghegan,
with thanks for the time and effort contributed.
Various issues reported via sqlsmith by Andreas Seltenreich
Authors: Pavan Deolasee, Simon Riggs
Reviewer: Peter Geoghegan, Amit Langote, Tomas Vondra, Simon Riggs
Discussion:
https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.comhttps://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com
Coverity complained about possible buffer overrun in two places added by
commit 1eb6d6527, and AFAICS it's reasonable to worry: even granting that
the WAL originator properly truncated the commit GID to GIDSIZE, we should
not really bet our lives on that having the same value as it does in the
current build. Hence, use strlcpy() not strcpy(), and adjust the pointer
advancement logic to be sure we skip over the whole source string even if
strlcpy() truncated it.
In the previous coding, skipped pages were mostly zeroes, but they still
had valid WAL page headers. That makes them very much less compressible
than an unbroken string of zeroes would be --- about 10X worse for bzip2
compression, for instance. We don't need those headers, so tweak the logic
so that we zero them out.
Chapman Flack, reviewed by Daniel Gustafsson
Discussion: https://postgr.es/m/579297F8.7020107@anastigmatix.net
In btree and SP-GiST indexes, move the responsibility for calling
IndexFreeSpaceMapVacuum from the vacuumcleanup phase to the bulkdelete
phase, and do it if and only if we found some pages that could be put into
FSM. As in commit 851a26e26, the idea is to make free pages visible to FSM
searchers sooner when vacuuming very large tables (large enough to need
multiple bulkdelete scans). This adds more redundant work than that commit
did, since we have to scan the entire index FSM each time rather than being
able to localize what needs to be updated; but it still seems worthwhile.
However, we can buy something back by not touching the FSM at all when
there are no pages that can be put in it. That will result in slower
recovery from corrupt upper FSM pages in such a scenario, but it doesn't
seem like that's a case we need to optimize for.
Hash indexes don't use FSM at all. GIN, GiST, and bloom indexes update
FSM during the vacuumcleanup phase not bulkdelete, so that doing something
comparable to this would be a much more invasive change, and it's not clear
it's worth it. BRIN indexes do things sufficiently differently that this
change doesn't apply to them, either.
Claudio Freire, reviewed by Masahiko Sawada and Jing Wang, some additional
tweaks by me
Discussion: https://postgr.es/m/CAGTBQpYR0uJCNTt3M5GOzBRHo+-GccNO1nCaQ8yEJmZKSW5q1A@mail.gmail.com
Predicate locks are used on per page basis only if fastupdate = off, in
opposite case predicate lock on pending list will effectively lock whole index,
to reduce locking overhead, just lock a relation. Entry and posting trees are
essentially B-tree, so locks are acquired on leaf pages only.
Author: Shubham Barai with some editorization by me and Dmitry Ivanov
Review by: Alexander Korotkov, Dmitry Ivanov, Fedor Sigaev
Discussion: https://www.postgresql.org/message-id/flat/CALxAEPt5sWW+EwTaKUGFL5_XFcZ0MuGBcyJ70oqbWqr42YKR8Q@mail.gmail.com
FreeSpaceMapVacuumRange has the same effect, is more efficient if many
pages are involved, and makes fewer assumptions about how it's used.
Notably, Claudio Freire pointed out that UpdateFreeSpaceMap could fail
if the specified freespace value isn't the maximum possible. This isn't
a problem for the single existing user, but the function represents an
attractive nuisance IMO, because it's named as though it were a
general-purpose update function and its limitations are undocumented.
In any case we don't need multiple ways to get the same result.
In passing, do some code review and cleanup in RelationAddExtraBlocks.
In particular, I see no excuse for it to omit the PageIsNew safety check
that's done in the mainline extension path in RelationGetBufferForTuple.
Discussion: https://postgr.es/m/CAGTBQpYR0uJCNTt3M5GOzBRHo+-GccNO1nCaQ8yEJmZKSW5q1A@mail.gmail.com
Store GID of 2PC in commit/abort WAL records when wal_level = logical.
This allows logical decoding to send the SAME gid to subscribers
across restarts of logical replication.
Track relica origin replay progress for 2PC.
(Edited from patch 0003 in the logical decoding 2PC series.)
Authors: Nikhil Sontakke, Stas Kelvich
Reviewed-by: Simon Riggs, Andres Freund
Instead using memset to set tts_isnull, call the new
slot_getmissingattrs().
Also fix a bug (= instead of >=) in the code generation. Normally = is
correct, but when repeatedly deforming fields not in a
tuple (e.g. deform up to natts + 1 and then natts + 2) >= is needed.
Discussion: https://postgr.es/m/20180328010053.i2qvsuuusst4lgmc@alap3.anarazel.de
Currently adding a column to a table with a non-NULL default results in
a rewrite of the table. For large tables this can be both expensive and
disruptive. This patch removes the need for the rewrite as long as the
default value is not volatile. The default expression is evaluated at
the time of the ALTER TABLE and the result stored in a new column
(attmissingval) in pg_attribute, and a new column (atthasmissing) is set
to true. Any existing row when fetched will be supplied with the
attmissingval. New rows will have the supplied value or the default and
so will never need the attmissingval.
Any time the table is rewritten all the atthasmissing and attmissingval
settings for the attributes are cleared, as they are no longer needed.
The most visible code change from this is in heap_attisnull, which
acquires a third TupleDesc argument, allowing it to detect a missing
value if there is one. In many cases where it is known that there will
not be any (e.g. catalog relations) NULL can be passed for this
argument.
Andrew Dunstan, heavily modified from an original patch from Serge
Rielau.
Reviewed by Tom Lane, Andres Freund, Tomas Vondra and David Rowley.
Discussion: https://postgr.es/m/31e2e921-7002-4c27-59f5-51f08404c858@2ndQuadrant.com
Originally, we treated memory context names as potentially variable in
all cases, and therefore always copied them into the context header.
Commit 9fa6f00b1 rethought this a little bit and invented a distinction
between fixed and variable names, skipping the copy step for the former.
But we can make things both simpler and more useful by instead allowing
there to be two parts to a context's identification, a fixed "name" and
an optional, variable "ident". The name supplied in the context create
call is now required to be a compile-time-constant string in all cases,
as it is never copied but just pointed to. The "ident" string, if
wanted, is supplied later. This is needed because typically we want
the ident to be stored inside the context so that it's cleaned up
automatically on context deletion; that means it has to be copied into
the context before we can set the pointer.
The cost of this approach is basically just an additional pointer field
in struct MemoryContextData, which isn't much overhead, and is bought
back entirely in the AllocSet case by not needing a headerSize field
anymore, since we no longer have to cope with variable header length.
In addition, we can simplify the internal interfaces for memory context
creation still further, saving a few cycles there. And it's no longer
true that a custom identifier disqualifies a context from participating
in aset.c's freelist scheme, so possibly there's some win on that end.
All the places that were using non-compile-time-constant context names
are adjusted to put the variable info into the "ident" instead. This
allows more effective identification of those contexts in many cases;
for example, subsidary contexts of relcache entries are now identified
by both type (e.g. "index info") and relname, where before you got only
one or the other. Contexts associated with PL function cache entries
are now identified more fully and uniformly, too.
I also arranged for plancache contexts to use the query source string
as their identifier. This is basically free for CachedPlanSources, as
they contained a copy of that string already. We pay an extra pstrdup
to do it for CachedPlans. That could perhaps be avoided, but it would
make things more fragile (since the CachedPlanSource is sometimes
destroyed first). I suspect future improvements in error reporting will
require CachedPlans to have a copy of that string anyway, so it's not
clear that it's worth moving mountains to avoid it now.
This also changes the APIs for context statistics routines so that the
context-specific routines no longer assume that output goes straight
to stderr, nor do they know all details of the output format. This
is useful immediately to reduce code duplication, and it also allows
for external code to do something with stats output that's different
from printing to stderr.
The reason for pushing this now rather than waiting for v12 is that
it rethinks some of the API changes made by commit 9fa6f00b1. Seems
better for extension authors to endure just one round of API changes
not two.
Discussion: https://postgr.es/m/CAB=Je-FdtmFZ9y9REHD7VsSrnCkiBhsA4mdsLKSPauwXtQBeNA@mail.gmail.com
If the value of an index expression is unchanged after UPDATE,
allow HOT updates where previously we disallowed them, giving
a significant performance boost in those cases.
Particularly useful for indexes such as JSON->>field where the
JSON value changes but the indexed value does not.
Submitted as "surjective indexes" patch, now enabled by use
of new "recheck_on_update" parameter.
Author: Konstantin Knizhnik
Reviewer: Simon Riggs, with much wordsmithing and some cleanup
Add page-level predicate locking, due to gist's code organization, patch seems
close to trivial: add check before page changing, add predicate lock before page
scanning. Although choosing right place to check is not simple: it should not
be called during index build, it should support insertion of new downlink and so
on.
Author: Shubham Barai with editorization by me and Alexander Korotkov
Reviewed by: Alexander Korotkov, Andrey Borodin, me
Discussion: https://www.postgresql.org/message-id/flat/CALxAEPtdcANpw5ePU3LvnTP8HCENFw6wygupQAyNBgD-sG3h0g@mail.gmail.com
Performing JIT compilation for deforming gains performance benefits
over unJITed deforming from compile-time knowledge of the tuple
descriptor. Fixed column widths, NOT NULLness, etc can be taken
advantage of.
Right now the JITed deforming is only used when deforming tuples as
part of expression evaluation (and obviously only if the descriptor is
known). It's likely to be beneficial in other cases, too.
By default tuple deforming is JITed whenever an expression is JIT
compiled. There's a separate boolean GUC controlling it, but that's
expected to be primarily useful for development and benchmarking.
Docs will follow in a later commit containing docs for the whole JIT
feature.
Author: Andres Freund
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
The listed numbers disagreed with the ones being used in the symbols;
but instead of just fixing the numbers in the comment, use the symbolic
name instead, which seems clearer.
This has been wrong all along, so apply back to 9.5 where BRIN was
introduced.
Reported-by: Tomas Vondra
Discussion: https://postgr.es/m/5ff514f2-8b1e-6366-b11c-8e2ed442562d@2ndquadrant.com
Remember the last page of an index insert if it's the rightmost leaf
page. If the next entry belongs on and can fit in the remembered page,
insert the new entry there as long as we can get a lock on the page.
Otherwise, fall back on the more expensive method of searching for
the right place to insert the entry.
This provides a performance improvement for the common case where an
index entry is for monotonically increasing or nearly monotonically
increasing value such as an identity field or a current timestamp.
Pavan Deolasee
Reviewed by Claudio Freire, Simon Riggs and Peter Geoghegan
Discussion: https://postgr.es/m/CABOikdM9DrupjyKZZFM5k8-0RCDs1wk6JzEkg7UgSW6QzOwMZw@mail.gmail.com
Per the project style guide, details and hints should have leading
capitalization and end with a period. On the other hand, errcontext should
not be capitalized and should not end with a period. To support well
formatted error contexts in dblink, extend dblink_res_error() to take a
format+arguments rather than a hardcoded string.
Daniel Gustafsson
Discussion: https://postgr.es/m/B3C002C8-21A0-4F53-A06E-8CAB29FCF295@yesql.se
Count the number of tuples in the index honestly, instead of assuming
that it's the same as the number of tuples in the heap. (It might be
different if the index is partial.)
Back-patch to all supported versions.
Tomas Vondra
Discussion: https://postgr.es/m/3b3d8eac-c709-0d25-088e-b98339a1b28a@2ndquadrant.com
The original coding of the SP-GiST scan traversalValue feature (commit
ccd6eb49a) arranged for traversal values to be stored in the query's main
executor context. That's fine if there's only one index scan per query,
but if there are many, we have a memory leak as successive scans create
new traversal values. Fix it by creating a separate memory context for
traversal values, which we can reset during spgrescan(). Back-patch
to 9.6 where this code was introduced.
In principle, adding the traversalCxt field to SpGistScanOpaqueData
creates an ABI break in the back branches. But I (tgl) have little
sympathy for extensions including spgist_private.h, so I'm not very
worried about that. Alternatively we could stick the new field at the
end of the struct in back branches, but that has its own downsides.
Anton Dignös, reviewed by Alexander Kuzmenkov
Discussion: https://postgr.es/m/CALNdv1jb6y2Te-m8xHLxLX12RsBmZJ1f4hESX7J0HjgyOhA9eA@mail.gmail.com
"UPDATE/DELETE WHERE CURRENT OF cursor_name" failed, with an error message
like "cannot extract system attribute from virtual tuple", if the cursor
was using a index-only scan for the target table. Fix it by digging the
current TID out of the indexscan state.
It seems likely that the same failure could occur for CustomScan plans
and perhaps some FDW plan types, so that leaving this to be treated as an
internal error with an obscure message isn't as good an idea as it first
seemed. Hence, add a bit of heaptuple.c infrastructure to let us deliver
a more on-topic message. I chose to make the message match what you get
for the case where execCurrentOf can't identify the target scan node at
all, "cursor "foo" is not a simply updatable scan of table "bar"".
Perhaps it should be different, but we can always adjust that later.
In the future, it might be nice to provide hooks that would let custom
scan providers and/or FDWs deal with this in other ways; but that's
not a suitable topic for a back-patchable bug fix.
It's been like this all along, so back-patch to all supported branches.
Yugo Nagata and Tom Lane
Discussion: https://postgr.es/m/20180201013349.937dfc5f.nagata@sraoss.co.jp
In some cases, these were different for no apparent reason, making
debugging unnecessarily mysterious.
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Instead of embedding the savepoint name in a list and then requiring
complex code to unpack it, just add another struct field to store it
directly.
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
We call this thing a "transaction block" everywhere except in a few
functions, where it is mysteriously called a "transaction chain". In
the SQL standard, a transaction chain is something different. So rename
these functions to match the common terminology.
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Autovacuum's 'workitem' request queue is of limited size, so requests
can fail if they arrive more quickly than autovacuum can process them.
Emit a log message when this happens, to provide better visibility of
this.
Backpatch to 10. While this represents an API change for
AutoVacuumRequestWork, that function is not yet prepared to deal with
external modules calling it, so there doesn't seem to be any risk (other
than log spam, that is.)
Author: Masahiko Sawada
Reviewed-by: Fabrízio Mello, Ildar Musin, Álvaro Herrera
Discussion: https://postgr.es/m/CAD21AoB1HrQhp6_4rTyHN5kWEJCEsG8YzsjZNt-ctoXSn5Uisw@mail.gmail.com
Sloppy coding in this function could lead to leaking a VM buffer pin,
or to attempting to free the same pin twice. Repair. While at it,
reduce the code's tendency to free and reacquire the same page pin.
Back-patch to 9.6; before that, this routine did not concern itself
with VM pages.
Amit Kapila and Tom Lane
Discussion: https://postgr.es/m/CAA4eK1KJKwhc=isgTQHjM76CAdVswzNeAuZkh_cx-6QgGkSEgA@mail.gmail.com
Previously, it just returned the heap tuple count, which might be only an
estimate, and would be completely the wrong thing if the index is partial.
Since this function scans every index page anyway to find free pages,
it's practically free to count the surviving index tuples. Let's do that
and return an accurate count.
This is easily visible as a wrong reltuples value for a partial GiST
index following VACUUM, so back-patch to all supported branches.
Andrey Borodin, reviewed by Michail Nikolaev
Discussion: https://postgr.es/m/151956654251.6915.675951950408204404.pgcf@coridan.postgresql.org
Commit 4800f16a7a added some sanity checks to ensure we don't
accidentally corrupt data, but in one of them we failed to consider the
effects of a database upgraded from 9.2 or earlier, where a tuple
exclusively locked prior to the upgrade has a slightly different bit
pattern. Fix that by using the macro that we fixed in commit
74ebba84ae for similar situations.
Reported-by: Alexandre Garcia
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/CAPYLKR6yxV4=pfW0Gwij7aPNiiPx+3ib4USVYnbuQdUtmkMaEA@mail.gmail.com
Andres suspects that this bug may have wider ranging consequences, but I
couldn't find anything.
Use IndexTupleSize everywhere, instead. Also, remove IndexTupleSize's
internal typecast, as that's not really needed and might mask coding
errors. Change some pointer variable datatypes in the call sites
to compensate for that and make it clearer what we're assuming.
Ildar Musin, Robert Haas, Stephen Frost
Discussion: https://postgr.es/m/0274288e-9e88-13b6-c61c-7b36928bf221@postgrespro.ru
Previously tts_off was, for unknown reasons, of type long. For one
that's unnecessary as tuples are restricted in length, for another
long would be a bad choice of type even if that weren't the case, as
it's not reliably wider than an int. Also HeapTupleHeader->t_len is a
uint32.
This is split off from a larger patch implementing JITed tuple
deforming. Seems like an independent improvement, as tiny as it is.
Author: Andres Freund
All of these are false positives, but in each case a fair amount of
analysis is needed to see that, and it's not too surprising that not all
compilers are smart enough. (In particular, in the logtape.c case, a
compiler lacking the knowledge provided by the Assert would almost surely
complain, so that this warning will be seen in any non-assert build.)
Some of these are of long standing while others are pretty recent,
but it only seems worth fixing them in HEAD.
Jaime Casanova, tweaked a bit by me
Discussion: https://postgr.es/m/CAJGNTeMcYAMJdPAom52dppLMtF-UnEZi0dooj==75OEv1EoBZA@mail.gmail.com
This patch adds the ability to use "RANGE offset PRECEDING/FOLLOWING"
frame boundaries in window functions. We'd punted on that back in the
original patch to add window functions, because it was not clear how to
do it in a reasonably data-type-extensible fashion. That problem is
resolved here by adding the ability for btree operator classes to provide
an "in_range" support function that defines how to add or subtract the
RANGE offset value. Factoring it this way also allows the operator class
to avoid overflow problems near the ends of the datatype's range, if it
wishes to expend effort on that. (In the committed patch, the integer
opclasses handle that issue, but it did not seem worth the trouble to
avoid overflow failures for datetime types.)
The patch includes in_range support for the integer_ops opfamily
(int2/int4/int8) as well as the standard datetime types. Support for
other numeric types has been requested, but that seems like suitable
material for a follow-on patch.
In addition, the patch adds GROUPS mode which counts the offset in
ORDER-BY peer groups rather than rows, and it adds the frame_exclusion
options specified by SQL:2011. As far as I can see, we are now fully
up to spec on window framing options.
Existing behaviors remain unchanged, except that I changed the errcode
for a couple of existing error reports to meet the SQL spec's expectation
that negative "offset" values should be reported as SQLSTATE 22013.
Internally and in relevant parts of the documentation, we now consistently
use the terminology "offset PRECEDING/FOLLOWING" rather than "value
PRECEDING/FOLLOWING", since the term "value" is confusingly vague.
Oliver Ford, reviewed and whacked around some by me
Discussion: https://postgr.es/m/CAGMVOdu9sivPAxbNN0X+q19Sfv9edEPv=HibOJhB14TJv_RCQg@mail.gmail.com
Up to now, useful info for writing a new btree opclass has been buried
in the backend's nbtree/README file. Let's move it into the SGML docs,
in preparation for extending it with info about "in_range" functions
in the upcoming window RANGE patch.
To do this, I chose to create a new chapter for btree indexes in Part VII
(Internals), parallel to the chapters that exist for the newer index AMs.
This is a pretty short chapter as-is. At some point somebody might care
to flesh it out with more detail about btree internals, but that is
beyond the scope of my ambition for today.
Discussion: https://postgr.es/m/23141.1517874668@sss.pgh.pa.us
Commit 445dbd82a basically missed the point of commit d46633506,
which was that we shouldn't allow shm_toc_lookup() failure to lead
to a core dump or assertion crash, because the odds of such a
failure should never be considered negligible. It's correct that
we can't expect the PARALLEL_KEY_ERROR_QUEUE TOC entry to be there
if we have no workers. But if we have no workers, we're not going
to do anything in this function with the lookup result anyway,
so let's just skip it. That lets the code use the easy-to-prove-safe
noError=false case, rather than anything requiring effort to review.
Back-patch to v10, like the previous commit.
Discussion: https://postgr.es/m/3647.1517601675@sss.pgh.pa.us
To make this work, tuplesort.c and logtape.c must also support
parallelism, so this patch adds that infrastructure and then applies
it to the particular case of parallel btree index builds. Testing
to date shows that this can often be 2-3x faster than a serial
index build.
The model for deciding how many workers to use is fairly primitive
at present, but it's better than not having the feature. We can
refine it as we get more experience.
Peter Geoghegan with some help from Rushabh Lathia. While Heikki
Linnakangas is not an author of this patch, he wrote other patches
without which this feature would not have been possible, and
therefore the release notes should possibly credit him as an author
of this feature. Reviewed by Claudio Freire, Heikki Linnakangas,
Thomas Munro, Tels, Amit Kapila, me.
Discussion: http://postgr.es/m/CAM3SWZQKM=Pzc=CAHzRixKjp2eO5Q0Jg1SoFQqeXFQ647JiwqQ@mail.gmail.com
Discussion: http://postgr.es/m/CAH2-Wz=AxWqDoVvGU7dq856S4r6sJAj6DBn7VMtigkB33N5eyg@mail.gmail.com
Once this function has been called, we know that all workers have
started and attached to their error queues -- so if any of them
subsequently exit uncleanly, we'll be sure to throw an ERROR promptly.
Otherwise, users of the ParallelContext machinery must be careful not
to wait forever for a worker that has failed to start. Parallel query
manages to work without needing this for reasons explained in new
comments added by this patch, but it's a useful primitive for other
parallel operations, such as the pending patch to make creating a
btree index run in parallel.
Amit Kapila, revised by me. Additional review by Peter Geoghegan.
Discussion: http://postgr.es/m/CAA4eK1+e2MzyouF5bg=OtyhDSX+=Ao=3htN=T-r_6s3gCtKFiw@mail.gmail.com
We have a lot of code in which option names, which from the user's
viewpoint are logically keywords, are passed through the grammar as plain
identifiers, and then matched to string literals during command execution.
This approach avoids making words into lexer keywords unnecessarily. Some
places matched these strings using plain strcmp, some using pg_strcasecmp.
But the latter should be unnecessary since identifiers would have been
downcased on their way through the parser. Aside from any efficiency
concerns (probably not a big factor), the lack of consistency in this area
creates a hazard of subtle bugs due to different places coming to different
conclusions about whether two option names are the same or different.
Hence, standardize on using strcmp() to match any option names that are
expected to have been fed through the parser.
This does create a user-visible behavioral change, which is that while
formerly all of these would work:
alter table foo set (fillfactor = 50);
alter table foo set (FillFactor = 50);
alter table foo set ("fillfactor" = 50);
alter table foo set ("FillFactor" = 50);
now the last case will fail because that double-quoted identifier is
different from the others. However, none of our documentation says that
you can use a quoted identifier in such contexts at all, and we should
discourage doing so since it would break if we ever decide to parse such
constructs as true lexer keywords rather than poor man's substitutes.
So this shouldn't create a significant compatibility issue for users.
Daniel Gustafsson, reviewed by Michael Paquier, small changes by me
Discussion: https://postgr.es/m/29405B24-564E-476B-98C0-677A29805B84@yesql.se
Since 9.6, heavyweight locking is not an abstract and unhandled
concern of the parallel machinery, but rather something to which
we have a specific approach.
Commit 28724fd90d fixed things so that
if a background worker fails to start due to fork() failure or because
it is terminated before startup succeeds, BGWH_STOPPED will be
reported. However, that only helps if the code that uses the
background worker machinery notices the change in status, and the code
in parallel.c did not.
To fix that, do two things. First, make sure that when a worker
exits, it triggers the leader to read from error queues. That way, if
a worker which has attached to an error queue exits uncleanly, the
leader is sure to throw some error, either the contents of the
ErrorResponse sent by the worker, or "lost connection to parallel
worker" if it exited without sending one. To cover the case where
the worker never starts up in the first place or exits before
attaching to the error queue, the ParallelContext now keeps track
of which workers have sent at least one message via the error
queue. A worker which sends no messages by the time the parallel
operation finishes will be checked to see whether it exited before
attaching to the error queue; if so, a new error message, "parallel
worker failed to initialize", will be reported. If not, we'll
continue to wait until it either starts up and exits cleanly, starts
up and exits uncleanly, or fails to start, and then take the
appropriate action.
Patch by me, reviewed by Amit Kapila.
Discussion: http://postgr.es/m/CA+TgmoYnBgXgdTu6wk5YPdWhmgabYc9nY_pFLq=tB=FSLYkD8Q@mail.gmail.com
AclObjectKind was basically just another enumeration for object types,
and we already have a preferred one for that. It's only used in
aclcheck_error. By using ObjectType instead, we can also give some more
precise error messages, for example "index" instead of "relation".
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
Alvaro Herrera
Teodor Sigaev
Tom Lane
Magnus Hagander
Peter Eisentraut
Heikki Linnakangas
Andrew Dunstan
Simon Riggs
Stephen Frost
Andres Freund
Bruce Momjian
Robert Haas