Commit 0668719801 changed XLogPageRead() so that it validated the page
header, if invalid page header was found reset the error message and
retried reading the page, to fix the scenario where streaming standby
got stuck at a continuation record. This change hid the error message
about invalid page header, which would make it harder for users to
investigate what the actual issue was found in WAL.
To fix the issue, this commit makes XLogPageRead() report the error
message when invalid page header is found.
When not in standby mode, an invalid page header should cause recovery
to end, not retry reading the page, so XLogPageRead() doesn't need to
validate the page header for the retry. Instead, ReadPageInternal() should
be responsible for the validation in that case. Therefore this commit
changes XLogPageRead() so that if not in standby mode it doesn't validate
the page header for the retry.
Reported-by: Yugo Nagata
Author: Yugo Nagata, Kyotaro Horiguchi
Reviewed-by: Ranier Vilela, Fujii Masao
Discussion: https://postgr.es/m/20210718045505.32f463ed6c227111038d8ae4@sraoss.co.jp
Some specific logic is done at the end of recovery when involving 2PC
transactions:
1) Call RecoverPreparedTransactions(), to recover the state of 2PC
transactions into memory (re-acquire locks, etc.).
2) ShutdownRecoveryTransactionEnvironment(), to move back to normal
operations, mainly cleaning up recovery locks and KnownAssignedXids
(including any 2PC transaction tracked previously).
3) Switch XLogCtl->SharedRecoveryState to RECOVERY_STATE_DONE, which is
the tipping point for any process calling RecoveryInProgress() to check
if the cluster is still in recovery or not.
Any snapshot taken between steps 2) and 3) would be empty, causing any
transaction relying on a snapshot at this point to potentially corrupt
data as there could still be some 2PC transactions to track, with
RecentXmin moving backwards on successive calls to GetSnapshotData() in
the same transaction.
As SharedRecoveryState is the point to take into account to know if it
is safe to discard KnownAssignedXids, this commit moves step 2) after
step 3), so as we can never finish with empty snapshots.
This exists since the introduction of hot standby, so backpatch all the
way down. The window with incorrect snapshots is extremely small, but I
have seen it when running 023_pitr_prepared_xact.pl, as did buildfarm
member fairywren. Thomas Munro also found it independently. Special
thanks to Andres Freund for taking the time to analyze this issue.
Reported-by: Thomas Munro, Michael Paquier
Analyzed-by: Andres Freund
Discussion: https://postgr.es/m/20210422203603.fdnh3fu2mmfp2iov@alap3.anarazel.de
Backpatch-through: 9.6
The "equality implies image equality" opclass infrastructure disallowed
deduplication in system catalog indexes and TOAST indexes before now.
That seemed like the right approach back when the infrastructure was
added by commit 612a1ab7, since ALTER INDEX cannot set deduplicate_items
to 'off' (due to an old implementation restriction). But that decision
now seems arbitrary at best. Remove special case handling implementing
this policy.
No catversion bump, since existing catalog indexes will still work.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-Wz=rYQHFaJ3WYBdK=xgwxKzaiGMSSrh-ZCREa-pS-7Zjew@mail.gmail.com
Commit ff9f111bce added some test code that's unportable and doesn't
add meaningful coverage. Remove it rather than try and get it to work
everywhere.
While at it, fix a typo in a log message added by the aforementioned
commit.
Backpatch to 14.
Discussion: https://postgr.es/m/3000074.1632947632@sss.pgh.pa.us
Commit 84f5c2908 forgot to consider the possibility that
EnsurePortalSnapshotExists could run inside a subtransaction with
lifespan shorter than the Portal's. In that case, the new active
snapshot would be popped at the end of the subtransaction, leaving
a dangling pointer in the Portal, with mayhem ensuing.
To fix, make sure the ActiveSnapshot stack entry is marked with
the same subtransaction nesting level as the associated Portal.
It's certainly safe to do so since we won't be here at all unless
the stack is empty; hence we can't create an out-of-order stack.
Let's also apply this logic in the case where PortalRunUtility
sets portalSnapshot, just to be sure that path can't cause similar
problems. It's slightly less clear that that path can't create
an out-of-order stack, so add an assertion guarding it.
Report and patch by Bertrand Drouvot (with kibitzing by me).
Back-patch to v11, like the previous commit.
Discussion: https://postgr.es/m/ff82b8c5-77f4-3fe7-6028-fcf3303e82dd@amazon.com
Physical replication always ships WAL segment files to replicas once
they are complete. This is a problem if one WAL record is split across
a segment boundary and the primary server crashes before writing down
the segment with the next portion of the WAL record: WAL writing after
crash recovery would happily resume at the point where the broken record
started, overwriting that record ... but any standby or backup may have
already received a copy of that segment, and they are not rewinding.
This causes standbys to stop following the primary after the latter
crashes:
LOG: invalid contrecord length 7262 at A8/D9FFFBC8
because the standby is still trying to read the continuation record
(contrecord) for the original long WAL record, but it is not there and
it will never be. A workaround is to stop the replica, delete the WAL
file, and restart it -- at which point a fresh copy is brought over from
the primary. But that's pretty labor intensive, and I bet many users
would just give up and re-clone the standby instead.
A fix for this problem was already attempted in commit 515e3d84a0, but
it only addressed the case for the scenario of WAL archiving, so
streaming replication would still be a problem (as well as other things
such as taking a filesystem-level backup while the server is down after
having crashed), and it had performance scalability problems too; so it
had to be reverted.
This commit fixes the problem using an approach suggested by Andres
Freund, whereby the initial portion(s) of the split-up WAL record are
kept, and a special type of WAL record is written where the contrecord
was lost, so that WAL replay in the replica knows to skip the broken
parts. With this approach, we can continue to stream/archive segment
files as soon as they are complete, and replay of the broken records
will proceed across the crash point without a hitch.
Because a new type of WAL record is added, users should be careful to
upgrade standbys first, primaries later. Otherwise they risk the standby
being unable to start if the primary happens to write such a record.
A new TAP test that exercises this is added, but the portability of it
is yet to be seen.
This has been wrong since the introduction of physical replication, so
backpatch all the way back. In stable branches, keep the new
XLogReaderState members at the end of the struct, to avoid an ABI
break.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Nathan Bossart <bossartn@amazon.com>
Discussion: https://postgr.es/m/202108232252.dh7uxf6oxwcy@alvherre.pgsql
Discussing the low level issue of nbtree VACUUM and recovery conflicts
in btvacuumpage() now seems inappropriate. The same issue is discussed
in nbtxlog.h, as well as in a comment block above _bt_delitems_vacuum().
The comment block made more sense when it was part of a broader
discussion of nbtree VACUUM "pin scans". These were removed by commit
9f83468b.
_bt_delitems_delete() is no longer the high-level entry point used by
index tuple deletion driven by index tuples whose LP_DEAD bits are set
(now called "simple index tuple deletion"). It became a lower level
routine that's only called by _bt_delitems_delete_check() following
commit d168b66682.
Remove obsolete reference to lazy_vacuum()'s onecall argument. The
function argument was removed by commit 3499df0dee.
Also remove adjoining comment block that introduces the wraparound
failsafe concept. Talking about the failsafe here no longer makes
sense, since lazy_vacuum() (and related functions) are no longer the
only place where the failsafe might be triggered. This has been the
case since commit c242baa4a8 taught VACUUM to consider triggering the
failsafe mechanism during its initial heap scan.
Point out that index tuple deletion generally needs a latestRemovedXid
value for the deletion operation's WAL record. This is bound to be the
most expensive part of the whole deletion operation now that it takes
place up front, during original execution.
This was arguably an oversight in commit 558a9165e0, which moved the
work required to generate these values from index deletion REDO routines
to original execution of index deletion operations.
Checking that an offset number isn't past the end of a heap page's line
pointer array was just a defensive sanity check for HOT-chain traversal
code before commit 3c3b8a4b. It's etrictly necessary now, though. Add
comments that reference the issue to code in heapam that needs to get it
right.
Per suggestion from Alexander Lakhin.
Discussion: https://postgr.es/m/f76a292c-9170-1aef-91a0-59d9443b99a3@gmail.com
It is not appropriate for deduplication to apply single value strategy
when triggered by a bottom-up index deletion pass. This wastes cycles
because later bottom-up deletion passes will overinterpret older
duplicate tuples that deduplication actually just skipped over "by
design". It also makes bottom-up deletion much less effective for low
cardinality indexes that happen to cross a meaningless "index has single
key value per leaf page" threshold.
To fix, slightly narrow the conditions under which deduplication's
single value strategy is considered. We already avoided the strategy
for a unique index, since our high level goal must just be to buy time
for VACUUM to run (not to buy space). We'll now also avoid it when we
just had a bottom-up pass that reported failure. The two cases share
the same high level goal, and already overlapped significantly, so this
approach is quite natural.
Oversight in commit d168b666, which added bottom-up index deletion.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WznaOvM+Gyj-JQ0X=JxoMDxctDTYjiEuETdAGbF5EUc3MA@mail.gmail.com
Backpatch: 14-, where bottom-up deletion was introduced.
I noticed that commit 0bead9af48 left this flag undocumented in
XLogSetRecordFlags, which led me to discover that the flag doesn't
actually do what the one comment on it said it does. Improve the
situation by adding some more comments.
Backpatch to 14, where the aforementioned commit appears.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/202109212119.c3nhfp64t2ql@alvherre.pgsql
A broken HOT chain is not an unexpected condition, even when the offset
number points past the end of the page's line pointer array.
heap_prune_chain() does not (and never has) treated this condition as
unexpected, so derivative code in heap_index_delete_tuples() shouldn't
do so either.
Oversight in commit 4228817449.
The assertion can probably only fail on Postgres 14 and master. Earlier
releases don't have commit 3c3b8a4b, which taught VACUUM to truncate the
line pointer array of heap pages. Backpatch all the same, just to be
consistent.
Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/17197-9438f31f46705182@postgresql.org
Backpatch: 12-, just like commit 4228817449.
Formerly, we sent signals for outgoing NOTIFY messages within
ProcessCompletedNotifies, which was also responsible for sending
relevant ones of those messages to our connected client. It therefore
had to run during the main-loop processing that occurs just before
going idle. This arrangement had two big disadvantages:
* Now that procedures allow intra-command COMMITs, it would be
useful to send NOTIFYs to other sessions immediately at COMMIT
(though, for reasons of wire-protocol stability, we still shouldn't
forward them to our client until end of command).
* Background processes such as replication workers would not send
NOTIFYs at all, since they never execute the client communication
loop. We've had requests to allow triggers running in replication
workers to send NOTIFYs, so that's a problem.
To fix these things, move transmission of outgoing NOTIFY signals
into AtCommit_Notify, where it will happen during CommitTransaction.
Also move the possible call of asyncQueueAdvanceTail there, to
ensure we don't bloat the async SLRU if a background worker sends
many NOTIFYs with no one listening.
We can also drop the call of asyncQueueReadAllNotifications,
allowing ProcessCompletedNotifies to go away entirely. That's
because commit 790026972 added a call of ProcessNotifyInterrupt
adjacent to PostgresMain's call of ProcessCompletedNotifies,
and that does its own call of asyncQueueReadAllNotifications,
meaning that we were uselessly doing two such calls (inside two
separate transactions) whenever inbound notify signals coincided
with an outbound notify. We need only set notifyInterruptPending
to ensure that ProcessNotifyInterrupt runs, and we're done.
The existing documentation suggests that custom background workers
should call ProcessCompletedNotifies if they want to send NOTIFY
messages. To avoid an ABI break in the back branches, reduce it
to an empty routine rather than removing it entirely. Removal
will occur in v15.
Although the problems mentioned above have existed for awhile,
I don't feel comfortable back-patching this any further than v13.
There was quite a bit of churn in adjacent code between 12 and 13.
At minimum we'd have to also backpatch 51004c717, and a good deal
of other adjustment would also be needed, so the benefit-to-risk
ratio doesn't look attractive.
Per bug #15293 from Michael Powers (and similar gripes from others).
Artur Zakirov and Tom Lane
Discussion: https://postgr.es/m/153243441449.1404.2274116228506175596@wrigleys.postgresql.org
All the code paths simplified here were already using a boolean or used
an expression that led to zero or one, making the extra bits
unnecessary.
Author: Justin Pryzby
Reviewed-by: Tom Lane, Michael Paquier, Peter Smith
Discussion: https://postgr.es/m/20210428182936.GE27406@telsasoft.com
Attempting to make hashfloat4() look as much as possible like
hashfloat8(), I'd figured I could replace NaNs with get_float4_nan()
before widening to float8. However, results from protosciurus
and topminnow show that on some platforms that produces a different
bit-pattern from get_float8_nan(), breaking the intent of ce773f230.
Rearrange so that we use the result of get_float8_nan() for all NaN
cases. As before, back-patch.
The IEEE 754 standard allows a wide variety of bit patterns for NaNs,
of which at least two ("NaN" and "-NaN") are pretty easy to produce
from SQL on most machines. This is problematic because our btree
comparison functions deem all NaNs to be equal, but our float hash
functions know nothing about NaNs and will happily produce varying
hash codes for them. That causes unexpected results from queries
that hash a column containing different NaN values. It could also
produce unexpected lookup failures when using a hash index on a
float column, i.e. "WHERE x = 'NaN'" will not find all the rows
it should.
To fix, special-case NaN in the float hash functions, not too much
unlike the existing special case that forces zero and minus zero
to hash the same. I arranged for the most vanilla sort of NaN
(that coming from the C99 NAN constant) to still have the same
hash code as before, to reduce the risk to existing hash indexes.
I dithered about whether to back-patch this into stable branches,
but ultimately decided to do so. It's a clear improvement for
queries that hash internally. If there is anybody who has -NaN
in a hash index, they'd be well advised to re-index after applying
this patch ... but the misbehavior if they don't will not be much
worse than the misbehavior they had before.
Per bug #17172 from Ma Liangzhu.
Discussion: https://postgr.es/m/17172-7505bea9e04e230f@postgresql.org
It doesn't make any sense to report this information, since VACUUM
VERBOSE reports on heap relation truncation directly. This was an
oversight in commit 7ab96cf6, which made VACUUM VERBOSE output a little
more consistent with nearby autovacuum-specific log output. Adjust
comments that describe how this is supposed to work in passing.
Also bring truncation-related VACUUM VERBOSE output in line with the
convention established for VACUUM VERBOSE output by commit f4f4a649.
Author: Peter Geoghegan <pg@bowt.ie>
Backpatch: 14-, where VACUUM VERBOSE's output changed.
The field hasn't been used since commit 3d351d91, which redefined
pg_class.reltuples to be -1 before the first VACUUM or ANALYZE.
Also rename a local variable of the same name ("old_rel_pages"). This is
used by relation truncation to represent the original relation size at
the start of the ongoing VACUUM operation. Rename it to orig_rel_pages,
since that's a lot clearer. (This name matches similar nearby code.)
Most data-corruption reports mention the location of the problem, but
this one failed to. Add it.
Backpatch all the way back. In 12 and older, also assign the
ERRCODE_DATA_CORRUPTED error code as was done in commit fd6ec93bf8 for
13 and later.
Discussion: https://postgr.es/m/202108191637.oqyzrdtnheir@alvherre.pgsql
Somehow, spgist overlooked the need to call pgstat_count_index_scan().
Hence, pg_stat_all_indexes.idx_scan and equivalent columns never
became nonzero for an SP-GiST index, although the related per-tuple
counters worked fine.
This fix works a bit differently from other index AMs, in that the
counter increment occurs in spgrescan not spggettuple/spggetbitmap.
It looks like this won't make the user-visible semantics noticeably
different, so I won't go to the trouble of introducing an is-this-
the-first-call flag just to make the counter bumps happen in the
same places.
Per bug #17163 from Christian Quest. Back-patch to all supported
versions.
Discussion: https://postgr.es/m/17163-b8c5cc88322a5e92@postgresql.org
Adjust track_io_timing related logging code added by commit 94d13d474d.
Make it consistent with other nearby autovacuum and autoanalyze logging
code by removing logic that suppressed zero millisecond outputs.
log_autovacuum_min_duration log output now reliably shows "read:" and
"write:" millisecond-based values in its report (when track_io_timing is
enabled).
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Stephen Frost <sfrost@snowman.net>
Discussion: https://postgr.es/m/CAH2-WznW0FNxSVQMSRazAMYNfZ6DR_gr5WE78hc6E1CBkkJpzw@mail.gmail.com
Backpatch: 14-, where the track_io_timing logging was introduced.
This order seems more natural. It starts with details that are
particular to heap and index data structures, and ends with system-level
costs incurred during the autovacuum worker's VACUUM/ANALYZE operation.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WzkzxK6ahA9xxsOftRtBX_R0swuHZsvo4QUbak1Bz7hb7Q@mail.gmail.com
Backpatch: 14-, which enhanced the log output in various ways.
This was arguably a minor oversight in commit b4af70cb, which cleaned up
the function signatures of functions that modify IndexBulkDeleteResult
variables.
Pengchengliu reported an assertion failure in a parallel woker while
performing a parallel scan using an overflowed snapshot. The proximate
cause is that TransactionXmin was set to an incorrect value. The
underlying cause is incorrect snapshot handling in parallel.c.
In particular, InitializeParallelDSM() was unconditionally calling
GetTransactionSnapshot(), because I (rhaas) mistakenly thought that
was always retrieving an existing snapshot whereas, at isolation
levels less than REPEATABLE READ, it's actually taking a new one. So
instead do this only at higher isolation levels where there actually
is a single snapshot for the whole transaction.
By itself, this is not a sufficient fix, because we still need to
guarantee that TransactionXmin gets set properly in the workers. The
easiest way to do that seems to be to install the leader's active
snapshot as the transaction snapshot if the leader did not serialize a
transaction snapshot. This doesn't affect the results of future
GetTrasnactionSnapshot() calls since those have to take a new snapshot
anyway; what we care about is the side effect of setting TransactionXmin.
Report by Pengchengliu. Patch by Greg Nancarrow, except for some comment
text which I supplied.
Discussion: https://postgr.es/m/002f01d748ac$eaa781a0$bff684e0$@tju.edu.cn
WAL records may span multiple segments, but XLogWrite() does not
wait for the entire record to be written out to disk before
creating archive status files. Instead, as soon as the last WAL page of
the segment is written, the archive status file is created, and the
archiver may process it. If PostgreSQL crashes before it is able to
write and flush the rest of the record (in the next WAL segment), the
wrong version of the first segment file lingers in the archive, which
causes operations such as point-in-time restores to fail.
To fix this, keep track of records that span across segments and ensure
that segments are only marked ready-for-archival once such records have
been completely written to disk.
This has always been wrong, so backpatch all the way back.
Author: Nathan Bossart <bossartn@amazon.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Ryo Matsumura <matsumura.ryo@fujitsu.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CBDDFA01-6E40-46BB-9F98-9340F4379505@amazon.com
This reverts the following commits:
1b5617eb84 Describe (auto-)analyze behavior for partitioned tables
0e69f705cc Set pg_class.reltuples for partitioned tables
41badeaba8 Document ANALYZE storage parameters for partitioned tables
0827e8af70 autovacuum: handle analyze for partitioned tables
There are efficiency issues in this code when handling databases with
large numbers of partitions, and it doesn't look like there isn't any
trivial way to handle those. There are some other issues as well. It's
now too late in the cycle for nontrivial fixes, so we'll have to let
Postgres 14 users continue to manually deal with ANALYZE their
partitioned tables, and hopefully we can fix the issues for Postgres 15.
I kept [most of] be280cdad2 ("Don't reset relhasindex for partitioned
tables on ANALYZE") because while we added it due to 0827e8af70, it is
a good bugfix in its own right, since it affects manual analyze as well
as autovacuum-induced analyze, and there's no reason to revert it.
I retained the addition of relkind 'p' to tables included by
pg_stat_user_tables, because reverting that would require a catversion
bump.
Also, in pg14 only, I keep a struct member that was added to
PgStat_TabStatEntry to avoid breaking compatibility with existing stat
files.
Backpatch to 14.
Discussion: https://postgr.es/m/20210722205458.f2bug3z6qzxzpx2s@alap3.anarazel.de
During a VACUUM or CLUSTER command, the initial output emits a
fully qualified relation path with namespace. The post-action
errmsg only emitted the relation name however, which may lead
to hard to parse output when using multiple jobs with vacuumdb
as the output from different jobs may be interleaved. Include
the full path in the post-action errmsg to be consistent with
the initial errmsg.
Author: Mike Fiedler <miketheman@gmail.com>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://postgr.es/m/CAMerE0oz+8G-aORZL_BJcPxnBqewZAvND4bSUysjz+r-oT1BxQ@mail.gmail.com
This commit ensures that the wait interval in the replay delay loop
waiting for an amount of time defined by recovery_min_apply_delay is
correctly handled on reload, recalculating the delay if this GUC value
is updated, based on the timestamp of the commit record being replayed.
The previous behavior would be problematic for example with replay
still waiting even if the delay got reduced or just cancelled. If the
apply delay was increased to a larger value, the wait would have just
respected the old value set, finishing earlier.
Author: Soumyadeep Chakraborty, Ashwin Agrawal
Reviewed-by: Kyotaro Horiguchi, Michael Paquier
Discussion: https://postgr.es/m/CAE-ML+93zfr-HLN8OuxF0BjpWJ17O5dv1eMvSE5jsj9jpnAXZA@mail.gmail.com
Backpatch-through: 9.6
This is a step toward storing stats in dynamic shared memory. As dynamic
shared memory segments are detached from just after before_shmem_exit()
callbacks are processed, but before on_shmem_exit() callbacks are, no stats
can be collected after before_shmem_exit() callbacks have been processed.
Parallel worker shutdown can cause stats to be emitted during DSM detach
callbacks, e.g. for SharedFileSet (which closes its files, which can causes
fd.c to emit stats about temporary files). Therefore parallel worker shutdown
needs to complete during the processing of before_shmem_exit callbacks.
One might think this problem could instead be solved by carefully ordering the
attaching to DSM segments, so that the pgstats segments get detached from
later than the parallel query ones. That turns out to not work because the
stats hash might need to grow which can cause new segments to be
allocated, which then will be detached from earlier.
There are two code changes:
First, call ParallelWorkerShutdown() via before_shmem_exit. That's a good idea
on its own, because other shutdown callbacks like ShutdownPostgres and
ShutdownAuxiliaryProcess are called via before_*.
Second, explicitly detach from the parallel query DSM segment, thereby
ensuring all stats are emitted during ParallelWorkerShutdown().
There are nicer solutions to these problems, but it's not obvious which of
those solutions is the correct one. As the shared memory stats work already is
a huge amount of work...
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210405092914.mmxqe7j56lsjfsej@alap3.anarazel.de
Discussion: https://postgr.es/m/20210803023612.iziacxk5syn2r4ut@alap3.anarazel.de
These have been unrelated since bgwriter and checkpointer were split into two
processes in 806a2aee37. As there several pending patches (shared memory
stats, extending the set of tracked IO / buffer statistics) that are made a
bit more awkward by the grouping, split them. Done separately to make
reviewing easier.
This does *not* change the contents of pg_stat_bgwriter or move fields out of
bgwriter/checkpointer stats that arguably do not belong in either. However
pgstat_fetch_global() was renamed and split into
pgstat_fetch_stat_checkpointer() and pgstat_fetch_stat_bgwriter().
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210405092914.mmxqe7j56lsjfsej@alap3.anarazel.de
Oversight in commit 3499df0d, which generalized the reloption as a way
of giving users a way to consistently avoid VACUUM's index bypass
optimization.
Per off-list report from Nikolay Shaplov.
Backpatch: 14-, where index cleanup reloption was extended.
Start up the checkpointer and bgwriter during crash recovery (except in
--single mode), as we do for replication. This wasn't done back in
commit cdd46c76 out of caution. Now it seems like a better idea to make
the environment as similar as possible in both cases. There may also be
some performance advantages.
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ8NRsqgkZEnsnRc2MFROBV-jCnacbYvtpptK2A9YYp9Q%40mail.gmail.com
They are used in code that runs both during normal operation and during
WAL replay, and needs to behave differently during replay. Move them to
xlogutils.c, because that's where we have other helper functions used by
redo routines.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/b3b71061-4919-e882-4857-27e370ab134a%40iki.fi
It should always be the case that the last checkpoint record is still
readable, because otherwise, a crash would leave us in a situation
from which we can't recover. Therefore the test removed by this patch
should always succeed. For it to fail, either there has to be a serious
bug in the code someplace, or the user has to be manually modifying
pg_wal while crash recovery is running. If it's the first one, we
should fix the bug. If it's the second one, they should stop, or
anyway they're doing so at their own risk. In neither case does
a full checkpoint instead of an end-of-recovery record seem like a
clear winner. Furthermore, rarely-taken code paths are particularly
vulnerable to bugs, so let's simplify by getting rid of this one.
Discussion: http://postgr.es/m/CA+TgmoYmw==TOJ6EzYb_vcjyS09NkzrVKSyBKUUyo1zBEaJASA@mail.gmail.com
CheckpointLock was removed in commit d18e75664a, and commit ce197e91d0
updated a leftover comment in CreateCheckPoint, but there was another
copy of it in CreateRestartPoint still.
Buildfarm shows that this test has a further failure mode when a
checkpoint starts earlier than expected, so we detect a "checkpoint
completed" line that's not the one we want. Change the config to try
and prevent this.
Per buildfarm
While at it, update one comment that was forgotten in commit
d18e75664a.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20210729.162038.534808353849568395.horikyota.ntt@gmail.com
If a file is truncated, we must update minRecoveryPoint. Once a file is
truncated, there's no going back; it would not be safe to stop recovery
at a point earlier than that anymore.
Commit 7bffc9b7bf changed xact_redo_commit() so that it updates
minRecoveryPoint on truncation, but forgot to change xact_redo_abort().
Back-patch to all supported versions.
Reported-by: mengjuan.cmj@alibaba-inc.com
Author: Fujii Masao
Reviewed-by: Heikki Linnakangas
Discussion: https://postgr.es/m/b029fce3-4fac-4265-968e-16f36ff4d075.mengjuan.cmj@alibaba-inc.com
Commit 2c03216d83 changed XLOG_FPI_FOR_HINT records so that they always
included full-page images even when full_page_writes was disabled. However,
in this setting, they don't need to do that because hint bit updates don't
need to be protected from torn writes.
Therefore, this commit makes XLOG_FPI_FOR_HINT records honor full_page_writes
setting. That is, XLOG_FPI_FOR_HINT records may include no full-page images
if full_page_writes is disabled, and WAL replay of them does nothing.
Reported-by: Zhang Wenjie
Author: Kyotaro Horiguchi
Reviewed-by: Fujii Masao
Discussion: https://postgr.es/m/tencent_60F11973A111EED97A8596FFECC4A91ED405@qq.com
When some slots are invalidated due to the max_slot_wal_keep_size limit,
the old segment horizon should move forward to stay within the limit.
However, in commit c655077639 we forgot to call KeepLogSeg again to
recompute the horizon after invalidating replication slots. In cases
where other slots remained, the limits would be recomputed eventually
for other reasons, but if all slots were invalidated, the limits would
not move at all afterwards. Repair.
Backpatch to 13 where the feature was introduced.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reported-by: Marcin Krupowicz <mk@071.ovh>
Discussion: https://postgr.es/m/17103-004130e8f27782c9@postgresql.org
As of v14, pg_depend contains almost 7000 "pin" entries recording
the OIDs of built-in objects. This is a fair amount of bloat for
every database, and it adds time to pg_depend lookups as well as
initdb. We can get rid of all of those entries in favor of an OID
range check, i.e. "OIDs below FirstUnpinnedObjectId are pinned".
(template1 and the public schema are exceptions. Those exceptions
are now wired into IsPinnedObject() instead of initdb's code for
filling pg_depend, but it's the same amount of cruft either way.)
The contents of pg_shdepend are modified likewise.
Discussion: https://postgr.es/m/3737988.1618451008@sss.pgh.pa.us
To add support for streaming transactions at prepare time into the
built-in logical replication, we need to do the following things:
* Modify the output plugin (pgoutput) to implement the new two-phase API
callbacks, by leveraging the extended replication protocol.
* Modify the replication apply worker, to properly handle two-phase
transactions by replaying them on prepare.
* Add a new SUBSCRIPTION option "two_phase" to allow users to enable
two-phase transactions. We enable the two_phase once the initial data sync
is over.
We however must explicitly disable replication of two-phase transactions
during replication slot creation, even if the plugin supports it. We
don't need to replicate the changes accumulated during this phase,
and moreover, we don't have a replication connection open so we don't know
where to send the data anyway.
The streaming option is not allowed with this new two_phase option. This
can be done as a separate patch.
We don't allow to toggle two_phase option of a subscription because it can
lead to an inconsistent replica. For the same reason, we don't allow to
refresh the publication once the two_phase is enabled for a subscription
unless copy_data option is false.
Author: Peter Smith, Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Sawada Masahiko, Vignesh C, Dilip Kumar, Takamichi Osumi, Greg Nancarrow
Tested-By: Haiying Tang
Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
Discussion: https://postgr.es/m/CAA4eK1+opiV4aFTmWWUF9h_32=HfPOW9vZASHarT0UA5oBrtGw@mail.gmail.com
The idea behind this patch is to design out bugs like the one fixed
by commit 9d523119f. Previously, once one did RelationOpenSmgr(rel),
it was considered okay to access rel->rd_smgr directly for some
not-very-clear interval. But since that pointer will be cleared by
relcache flushes, we had bugs arising from overreliance on a previous
RelationOpenSmgr call still being effective.
Now, very little code except that in rel.h and relcache.c should ever
touch the rd_smgr field directly. The normal coding rule is to use
RelationGetSmgr(rel) and not expect the result to be valid for longer
than one smgr function call. There are a couple of places where using
the function every single time seemed like overkill, but they are now
annotated with large warning comments.
Amul Sul, after an idea of mine.
Discussion: https://postgr.es/m/CANiYTQsU7yMFpQYnv=BrcRVqK_3U3mtAzAsJCaqtzsDHfsUbdQ@mail.gmail.com
This should have been removed in commit 7e30c186da, which split the loop
into two. Only the first loop uses the 'from' variable; updating it in
the second loop is bogus. It was never read after the first loop, so this
was harmless and surely optimized away by the compiler, but let's be tidy.
Backpatch to all supported versions.
Author: Ranier Vilela
Discussion: https://www.postgresql.org/message-id/CAEudQAoWq%2BAL3BnELHu7gms2GN07k-np6yLbukGaxJ1vY-zeiQ%40mail.gmail.com
This concerns pg_stop_backup() and BASE_BACKUP, when waiting for the
WAL segments required for a backup to be archived. This simplifies a
bit the handling of the wait event used in this code path.
Author: Bharath Rupireddy
Reviewed-by: Michael Paquier, Stephen Frost
Discussion: https://postgr.es/m/CALj2ACU4AdPCq6NLfcA-ZGwX7pPCK5FgEj-CAU0xCKzkASSy_A@mail.gmail.com
This has the advantage to make a process more responsive when the
postmaster dies, even if the wait time was rather limited as there was
only a 50ms timeout here. Another advantage of this change is for
monitoring, as we gain a new wait event for the end-of-vacuum
truncation.
Author: Bharath Rupireddy
Reviewed-by: Aleksander Alekseev, Thomas Munro, Michael Paquier
Discussion: https://postgr.es/m/CALj2ACU4AdPCq6NLfcA-ZGwX7pPCK5FgEj-CAU0xCKzkASSy_A@mail.gmail.com
This is reproducible with gcc using at least -O0. The last checks
validating the compression of a block could not be reached with this
variable not set, but let's be clean.
Oversight in 4035cd5, per buildfarm member lapwing.
The logic is implemented so as there can be a choice in the compression
used when building a WAL record, and an extra per-record bit is used to
track down if a block is compressed with PGLZ, LZ4 or nothing.
wal_compression, the existing parameter, is changed to an enum with
support for the following backward-compatible values:
- "off", the default, to not use compression.
- "pglz" or "on", to compress FPWs with PGLZ.
- "lz4", the new mode, to compress FPWs with LZ4.
Benchmarking has showed that LZ4 outclasses easily PGLZ. ZSTD would be
also an interesting choice, but going just with LZ4 for now makes the
patch minimalistic as toast compression is already able to use LZ4, so
there is no need to worry about any build-related needs for this
implementation.
Author: Andrey Borodin, Justin Pryzby
Reviewed-by: Dilip Kumar, Michael Paquier
Discussion: https://postgr.es/m/3037310D-ECB7-4BF1-AF20-01C10BB33A33@yandex-team.ru
The previous commit addressed the chief consequences of a race condition
between InstallXLogFileSegment() and KeepFileRestoredFromArchive(). Fix
three lesser consequences. A spurious durable_rename_excl() LOG message
remained possible. KeepFileRestoredFromArchive() wasted the proceeds of
WAL recycling and preallocation. Finally, XLogFileInitInternal() could
return a descriptor for a file that KeepFileRestoredFromArchive() had
already unlinked. That felt like a recipe for future bugs.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
Before a restartpoint finishes PreallocXlogFiles(), a startup process
KeepFileRestoredFromArchive() call can unlink the preallocated segment.
If a CHECKPOINT sql command had elicited the restartpoint experiencing
the race condition, that sql command failed. Moreover, the restartpoint
omitted its log_checkpoints message and some inessential resource
reclamation. Prevent the ERROR by skipping open() of the segment.
Since these consequences are so minor, no back-patch.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
Only initdb used it. initdb refuses to operate on a non-empty directory
and generally does not cope with pre-existing files of other kinds.
Hence, use the opportunity to simplify.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
Infrequently, the mismatch caused log_checkpoints messages and
TRACE_POSTGRESQL_CHECKPOINT_DONE() to witness an "added" count too high
by one. Since that consequence is so minor, no back-patch.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
When we cannot immediately acquire XactSLRULock in exclusive mode at
commit time, we add ourselves to a list of processes that need their XIDs
status update. We do this if the clog page where we need to update the
current transaction status is the same as the group leader's clog page,
otherwise, we allow the caller to clear it by itself. Now, when we can't
add ourselves to any group, we were not clearing the current proc if it
has already become a member of some group which was leading to an
assertion failure when the same proc was assigned to another backend after
the current backend exits.
Reported-by: Alexander Lakhin
Bug: 17072
Author: Amit Kapila
Tested-By: Alexander Lakhin
Backpatch-through: 11, where it was introduced
Discussion: https://postgr.es/m/17072-2f8764857ef2c92a@postgresql.org
The failsafe can trigger when index processing is already disabled.
This can happen when VACUUM's INDEX_CLEANUP parameter is "off" and the
failsafe happens to trigger. Remove assertions that assume that index
processing is directly tied to the failsafe.
Oversight in commit c242baa4, which made it possible for the failsafe to
trigger in a two-pass strategy VACUUM that has yet to make its first
call to lazy_vacuum_all_indexes().
Generalize the INDEX_CLEANUP VACUUM parameter (and the corresponding
reloption): make it into a ternary style boolean parameter. It now
exposes a third option, "auto". The "auto" option (which is now the
default) enables the "bypass index vacuuming" optimization added by
commit 1e55e7d1.
"VACUUM (INDEX_CLEANUP TRUE)" is redefined to once again make VACUUM
simply do any required index vacuuming, regardless of how few dead
tuples are encountered during the first scan of the target heap relation
(unless there are exactly zero). This gives users a way of opting out
of the "bypass index vacuuming" optimization, if for whatever reason
that proves necessary. It is also expected to be used by PostgreSQL
developers as a testing option from time to time.
"VACUUM (INDEX_CLEANUP FALSE)" does the same thing as it always has: it
forcibly disables both index vacuuming and index cleanup. It's not
expected to be used much in PostgreSQL 14. The failsafe mechanism added
by commit 1e55e7d1 addresses the same problem in a simpler way.
INDEX_CLEANUP can now be thought of as a testing and compatibility
option.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/CAH2-WznrBoCST4_Gxh_G9hA8NzGUbeBGnOUC8FcXcrhqsv6OHQ@mail.gmail.com
One of the error paths left *members uninitialized. That's not a live
bug, because most callers don't look at *members when the function
returns -1, but let's be tidy. One caller, in heap_lock_tuple(), does
"if (members != NULL) pfree(members)", but AFAICS it never passes an
invalid 'multi' value so it should not reach that error case.
The callers are also a bit inconsistent in their expectations.
heap_lock_tuple() pfrees the 'members' array if it's not-NULL, others
pfree() it if "nmembers >= 0", and others if "nmembers > 0". That's
not a live bug either, because the function should never return 0, but
add an Assert for that to make it more clear. I left the callers alone
for now.
I also moved the line where we set *nmembers. It wasn't wrong before,
but I like to do that right next to the 'return' statement, to make it
clear that it's always set on return.
Also remove one unreachable return statement after ereport(ERROR), for
brevity and for consistency with the similar if-block right after it.
Author: Greg Nancarrow with the additional changes by me
Backpatch-through: 9.6, all supported versions
Since commit c24dcd0cfd, we have been using pg_pread() to read the WAL
file, which doesn't change the seek position (unless we fall back to
the implementation in src/port/pread.c). Update comment accordingly.
Backpatch-through: 12, where we started to use pg_pread()
Bugfix commit 5fc89376 effectively made the lock_waiter_detected field
from vacuumlazy.c's global state struct into private state owned by
lazy_truncate_heap(). Finish this off by replacing the struct field
with a local variable.
The extra checks added by the recompression of toast data introduced in
bbe0a81 is proving to have a performance impact on VACUUM or CLUSTER
even if no recompression is done. This is more noticeable with more
toastable columns that contain non-NULL values.
Improvements could be done to make those extra checks less expensive,
but that's not material for 14 at this stage, and we are not sure either
if the code path of VACUUM FULL/CLUSTER is adapted for this job.
Per discussion with several people, including Andres Freund, Robert
Haas, Álvaro Herrera, Tom Lane and myself.
Discussion: https://postgr.es/m/20210527003144.xxqppojoiwurc2iz@alap3.anarazel.de
We were already reporting it, but only after the parallel workers were
finished, which is visibly much later than what happens in a serial
build.
With this change we report it when the leader starts its own sort phase
when participating in the build (the normal case). Now this might
happen a little later than when the workers start their sorting phases,
but a) communicating the actual phase start from workers is likely to be
a hassle, and b) the sort phase start is pretty fuzzy anyway, since
sorting per se is actually initiated by tuplesort.c internally earlier
than tuplesort_performsort() is called.
Backpatch to pg12, where the progress reporting code for CREATE INDEX
went in.
Reported-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Greg Nancarrow <gregn4422@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/1128176d-1eee-55d4-37ca-e63644422adb
This only happens if (1) the new standby has no WAL available locally,
(2) the new standby is starting from the old timeline, (3) the promotion
happened in the WAL segment from which the new standby is starting,
(4) the timeline history file for the new timeline is available from
the archive but the WAL files for are not (i.e. this is a race),
(5) the WAL files for the new timeline are available via streaming,
and (6) recovery_target_timeline='latest'.
Commit ee994272ca introduced this
logic and was an improvement over the previous code, but it mishandled
this case. If recovery_target_timeline='latest' and restore_command is
set, validateRecoveryParameters() can change recoveryTargetTLI to be
different from receiveTLI. If streaming is then tried afterward,
expectedTLEs gets initialized with the history of the wrong timeline.
It's supposed to be a list of entries explaining how to get to the
target timeline, but in this case it ends up with a list of entries
explaining how to get to the new standby's original timeline, which
isn't right.
Dilip Kumar and Robert Haas, reviewed by Kyotaro Horiguchi.
Discussion: http://postgr.es/m/CAFiTN-sE-jr=LB8jQuxeqikd-Ux+jHiXyh4YDiZMPedgQKup0g@mail.gmail.com
This tidies up some questionable coding which made use of
DatumGetPointer() for Datums being passed into functions where the
parameter is expected to be a cstring. We saw no compiler warnings with
the old code as the Pointer type used in DatumGetPointer() happens to
be a char * rather than a void *. However, that's no excuse and we should
be using the correct macro for the job.
Here we also make use of OutputFunctionCall() rather than using
FunctionCall1() directly to call the type's output function.
OutputFunctionCall() is the standard way to do this. It casts the
returned value to a cstring for us.
In passing get rid of a duplicate call to strlen(). Most compilers will
likely optimize away the 2nd call, but there may be some that won't. In
any case, this just aligns the code to some other nearby code that already
does this.
Discussion: https://postgr.es/m/CAApHDvq1D=ehZ8hey8Hz67N+_Zth0GHO5wiVCfv1YcGPMXJq0A@mail.gmail.com
Fix a few places that were using appendStringInfo() when they should have
been using appendStringInfoString(). Also some cases of
appendPQExpBuffer() that would have been better suited to use
appendPQExpBufferChar(), and finally, some places that used
appendPQExpBuffer() when appendPQExpBufferStr() would have suited better.
There are no bugs are being fixed here. The aim is just to make the code
use the most optimal function for the job.
All the code being changed here is new to PG14. It makes sense to fix
these before we branch for PG15. There are a few other places that we
could fix, but those cases are older code so fixing those seems less
worthwhile as it may cause unnecessary back-patching pain in the future.
Author: Hou Zhijie
Discussion: https://postgr.es/m/OS0PR01MB5716732158B1C4142C6FE375943D9@OS0PR01MB5716.jpnprd01.prod.outlook.com
Redefine '\0' (InvalidCompressionMethod) as meaning "if we need to
compress, use the current setting of default_toast_compression".
This allows '\0' to be a suitable default choice regardless of
datatype, greatly simplifying code paths that initialize tupledescs
and the like. It seems like a more user-friendly approach as well,
because now the default compression choice doesn't migrate into table
definitions, meaning that changing default_toast_compression is
usually sufficient to flip an installation's behavior; one needn't
tediously issue per-column ALTER SET COMPRESSION commands.
Along the way, fix a few minor bugs and documentation issues
with the per-column-compression feature. Adopt more robust
APIs for SetIndexStorageProperties and GetAttributeCompression.
Bump catversion because typical contents of attcompression will now
be different. We could get away without doing that, but it seems
better to ensure v14 installations all agree on this. (We already
forced initdb for beta2, anyway.)
Discussion: https://postgr.es/m/626613.1621787110@sss.pgh.pa.us
VACUUM FULL and CLUSTER can be used to enforce the use of the existing
compression method of a toastable column if a value currently stored is
compressed with a method that does not match the column's defined
method. The code in charge of decompressing and recompressing toast
values at rewrite left around the detoasted values, causing an
accumulation of memory allocated in TopTransactionContext.
When processing large relations, this could cause the system to run out
of memory. The detoasted values are not needed once their tuple is
rewritten, and this commit ensures that the necessary cleanup happens.
Issue introduced by bbe0a81d. The comments of the area are reordered a
bit while on it.
Reported-by: Andres Freund
Analyzed-by: Andres Freund
Author: Michael Paquier
Reviewed-by: Dilip Kumar
Discussion: https://postgr.es/m/20210521211929.pcehg6f23icwstdb@alap3.anarazel.de
The wraparound failsafe mechanism added by commit 1e55e7d1 handled the
one-pass strategy case (i.e. the "table has no indexes" case) by adding
a dedicated failsafe check. This made up for the fact that the usual
one-pass checks inside lazy_vacuum_all_indexes() cannot ever be reached
during a one-pass strategy VACUUM.
This approach failed to account for two-pass VACUUMs that opt out of
index vacuuming up-front. The INDEX_CLEANUP off case in the only case
that works like that.
Fix this by performing a failsafe check every 4GB during the first scan
of the heap, regardless of the details of the VACUUM. This eliminates
the special case, and will make the failsafe trigger more reliably.
Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/20210424002921.pb3t7h6frupdqnkp@alap3.anarazel.de
Now that attcompression is just a char, there's a lot of wasted
padding space after it. Move it into the group of char-wide
columns to save a net of 4 bytes per pg_attribute entry. While
we're at it, swap the order of attstorage and attalign to make for
a more logical grouping of these columns.
Also re-order actions in related code to match the new field ordering.
This patch also fixes one outright bug: equalTupleDescs() failed to
compare attcompression. That could, for example, cause relcache
reload to fail to adopt a new value following a change.
Michael Paquier and Tom Lane, per a gripe from Andres Freund.
Discussion: https://postgr.es/m/20210517204803.iyk5wwvwgtjcmc5w@alap3.anarazel.de
exec_for_query() normally tries to prefetch a few rows at a time
from the query being iterated over, so as to reduce executor
entry/exit overhead. Unfortunately this is unsafe if we have
COMMIT or ROLLBACK within the loop, because there might be
TOAST references in the data that we prefetched but haven't
yet examined. Immediately after the COMMIT/ROLLBACK, we have
no snapshots in the session, meaning that VACUUM is at liberty
to remove recently-deleted TOAST rows.
This was originally reported as a case triggering the "no known
snapshots" error in init_toast_snapshot(), but even if you miss
hitting that, you can get "missing toast chunk", as illustrated
by the added isolation test case.
To fix, just disable prefetching in non-atomic contexts. Maybe
there will be performance complaints prompting us to work harder
later, but it's not clear at the moment that this really costs
much, and I doubt we'd want to back-patch any complicated fix.
In passing, adjust that error message in init_toast_snapshot()
to be a little clearer about the likely cause of the problem.
Patch by me, based on earlier investigation by Konstantin Knizhnik.
Per bug #15990 from Andreas Wicht. Back-patch to v11 where
intra-procedure COMMIT was added.
Discussion: https://postgr.es/m/15990-eee2ac466b11293d@postgresql.org
If a promotion is triggered while recovery is paused, the paused state ends
and promotion continues. But previously in that case
pg_get_wal_replay_pause_state() returned 'paused' wrongly while a promotion
was ongoing.
This commit changes a standby promotion so that it marks the recovery
pause state as 'not paused' when it's triggered, to fix the issue.
Author: Fujii Masao
Reviewed-by: Dilip Kumar, Kyotaro Horiguchi
Discussion: https://postgr.es/m/f706876c-4894-0ba5-6f4d-79803eeea21b@oss.nttdata.com
Add a defensive "can't happen" error to code that handles nbtree posting
list splits (promote an existing assertion). This avoids a segfault in
the event of an insertion of a newitem that is somehow identical to an
existing non-pivot tuple in the index. An nbtree index should never
have two index tuples with identical TIDs.
This scenario is not particular unlikely in the event of any kind of
corruption that leaves the index in an inconsistent state relative to
the heap relation that is indexed. There are two known reports of
preventable hard crashes. Doing nothing seems unacceptable given the
general expectation that nbtree will cope reasonably well with corrupt
data.
Discussion: https://postgr.es/m/CAH2-Wz=Jr_d-dOYEEmwz0-ifojVNWho01eAqewfQXgKfoe114w@mail.gmail.com
Backpatch: 13-, where nbtree deduplication was introduced.
Formerly we just relied on operator classes that assert longValuesOK
to eventually shorten the leaf value enough to fit on an index page.
That fails since the introduction of INCLUDE-column support (commit
09c1c6ab4), because the INCLUDE columns might alone take up more
than a page, meaning no amount of leaf-datum compaction will get
the job done. At least with spgtextproc.c, that leads to an infinite
loop, since spgtextproc.c won't throw an error for not being able
to shorten the leaf datum anymore.
To fix without breaking cases that would otherwise work, add logic
to spgdoinsert() to verify that the leaf tuple size is decreasing
after each "choose" step. Some opclasses might not decrease the
size on every single cycle, and in any case, alignment roundoff
of the tuple size could obscure small gains. Therefore, allow
up to 10 cycles without additional savings before throwing an
error. (Perhaps this number will need adjustment, but it seems
quite generous right now.)
As long as we've developed this logic, let's back-patch it.
The back branches don't have INCLUDE columns to worry about, but
this seems like a good defense against possible bugs in operator
classes. We already know that an infinite loop here is pretty
unpleasant, so having a defense seems to outweigh the risk of
breaking things. (Note that spgtextproc.c is actually the only
known opclass with longValuesOK support, so that this is all moot
for known non-core opclasses anyway.)
Per report from Dilip Kumar.
Discussion: https://postgr.es/m/CAFiTN-uxP_soPhVG840tRMQTBmtA_f_Y8N51G7DKYYqDh7XN-A@mail.gmail.com
Knowing that a buggy opclass could cause an infinite insertion loop,
spgdoinsert() intended to allow its loop to be interrupted by query
cancel. However, that never actually worked, because in iterations
after the first, we'd be holding buffer lock(s) which would cause
InterruptHoldoffCount to be positive, preventing servicing of the
interrupt.
To fix, check if an interrupt is pending, and if so fall out of
the insertion loop and service the interrupt after we've released
the buffers. If it was indeed a query cancel, that's the end of
the matter. If it was a non-canceling interrupt reason, make use
of the existing provision to retry the whole insertion. (This isn't
as wasteful as it might seem, since any upper-level index tuples we
already created should be usable in the next attempt.)
While there's no known instance of such a bug in existing release
branches, it still seems like a good idea to back-patch this to
all supported branches, since the behavior is fairly nasty if a
loop does happen --- not only is it uncancelable, but it will
quickly consume memory to the point of an OOM failure. In any
case, this code is certainly not working as intended.
Per report from Dilip Kumar.
Discussion: https://postgr.es/m/CAFiTN-uxP_soPhVG840tRMQTBmtA_f_Y8N51G7DKYYqDh7XN-A@mail.gmail.com
Fujii Masao
Daniel Gustafsson
Michael Paquier
Peter Geoghegan
Alvaro Herrera
Tom Lane
Peter Eisentraut
Robert Haas
John Naylor
Andres Freund
Thomas Munro
Heikki Linnakangas
Amit Kapila
Noah Misch
Andrew Dunstan
David Rowley
Tomas Vondra