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  1. 31 Aug, 2021 1 commit
    • Tom Lane's avatar
      Fix missed lock acquisition while inlining new-style SQL functions. · 983d7033
      Tom Lane authored 
      When starting to use a query parsetree loaded from the catalogs,
we must begin by applying AcquireRewriteLocks(), to obtain the same
relation locks that the parser would have gotten if the query were
entered interactively, and to do some other cleanup such as dealing
with later-dropped columns.  New-style SQL functions are just as
subject to this rule as other stored parsetrees; however, of the
places dealing with such functions, only init_sql_fcache had gotten
the memo.  In particular, if we successfully inlined a new-style
set-returning SQL function that contained any relation references,
we'd either get an assertion failure or attempt to use those
relation(s) sans locks.

I also added AcquireRewriteLocks calls to fmgr_sql_validator and
print_function_sqlbody.  Desultory experiments didn't demonstrate any
failures in those, but I suspect that I just didn't try hard enough.
Certainly we don't expect nearby code paths to operate without locks.

On the same logic of it-ought-to-have-the-same-effects-as-the-old-code,
call pg_rewrite_query() in fmgr_sql_validator, too.  It's possible
that neither code path there needs to bother with rewriting, but
doing the analysis to prove that is beyond my goals for today.

Per bug #17161 from Alexander Lakhin.

Discussion: https://postgr.es/m/17161-048a1cdff8422800@postgresql.org
      983d7033
  3. 30 Aug, 2021 5 commits
  5. 28 Aug, 2021 4 commits
  7. 27 Aug, 2021 8 commits
  9. 25 Aug, 2021 9 commits
  11. 24 Aug, 2021 2 commits
    • Tom Lane's avatar
      Fix regexp misbehavior with capturing parens inside "{0}". · 244dd799
      Tom Lane authored 
      Regexps like "(.){0}...\1" drew an "invalid backreference number".
That's not unreasonable on its face, since the capture group will
never be matched if it's iterated zero times.  However, other engines
such as Perl's don't complain about this, nor do we throw an error for
related cases such as "(.)|\1", even though that backref can never
succeed either.  Also, if the zero-iterations case happens at runtime
rather than compile time --- say, "(x)*...\1" when there's no "x" to
be found --- that's not an error, we just deem the backref to not
match.  Making this even less defensible, no error was thrown for
nested cases such as "((.)){0}...\2"; and to add insult to injury,
those cases could result in assertion failures instead.  (It seems
that nothing especially bad happened in non-assert builds, though.)

Let's just fix it so that no error is thrown and instead the backref
is deemed to never match, so that compile-time detection of no
iterations behaves the same as run-time detection.

Per report from Mark Dilger.  This appears to be an aboriginal error
in Spencer's library, so back-patch to all supported versions.

Pre-v14, it turns out to also be necessary to back-patch one aspect of
commits cb76fbd7e/00116dee5, namely to create capture-node subREs with
the begin/end states of their subexpressions, not the current lp/rp
of the outer parseqatom invocation.  Otherwise delsub complains that
we're trying to disconnect a state from itself.  This is a bit scary
but code examination shows that it's safe: in the pre-v14 code, if we
want to wrap iteration around the subexpression, the first thing we do
is overwrite the atom's begin/end fields with new states.  So the
bogus values didn't survive long enough to be used for anything, except
if no iteration is required, in which case it doesn't matter.

Discussion: https://postgr.es/m/A099E4A8-4377-4C64-A98C-3DEDDC075502@enterprisedb.com
      244dd799
    • Amit Kapila's avatar
      Fix Alter Subscription's Add/Drop Publication behavior. · 5cfcd46e
      Amit Kapila authored 
      The current refresh behavior tries to just refresh added/dropped
publications but that leads to removing wrong tables from subscription. We
can't refresh just the dropped publication because it is quite possible
that some of the tables are removed from publication by that time and now
those will remain as part of the subscription. Also, there is a chance
that the tables that were part of the publication being dropped are also
part of another publication, so we can't remove those.

So, we decided that by default, add/drop commands will also act like
REFRESH PUBLICATION which means they will refresh all the publications. We
can keep the old behavior for "add publication" but it is better to be
consistent with "drop publication".

Author: Hou Zhijie
Reviewed-by: Masahiko Sawada, Amit Kapila
Backpatch-through: 14, where it was introduced
Discussion: https://postgr.es/m/OS0PR01MB5716935D4C2CC85A6143073F94EF9@OS0PR01MB5716.jpnprd01.prod.outlook.com
      5cfcd46e
  13. 23 Aug, 2021 3 commits
    • Tom Lane's avatar
      Prevent regexp back-refs from sometimes matching when they shouldn't. · 779557bd
      Tom Lane authored 
      The recursion in cdissect() was careless about clearing match data
for capturing parentheses after rejecting a partial match.  This
could allow a later back-reference to succeed when by rights it
should fail for lack of a defined referent.

To fix, think a little more rigorously about what the contract
between different levels of cdissect's recursion needs to be.
With the right spec, we can fix this using fewer rather than more
resets of the match data; the key decision being that a failed
sub-match is now explicitly responsible for clearing any matches
it may have set.

There are enough other cross-checks and optimizations in the code
that it's not especially easy to exhibit this problem; usually, the
match will fail as-expected.  Plus, regexps that are even potentially
vulnerable are most likely user errors, since there's just not much
point in writing a back-ref that doesn't always have a referent.
These facts perhaps explain why the issue hasn't been detected,
even though it's almost certainly a couple of decades old.

Discussion: https://postgr.es/m/151435.1629733387@sss.pgh.pa.us
      779557bd
    • Alvaro Herrera's avatar
      Avoid creating archive status ".ready" files too early · e3fb6170
      Alvaro Herrera authored 
      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: default avatarKyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: default avatarRyo Matsumura <matsumura.ryo@fujitsu.com>
Reviewed-by: default avatarAndrey Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CBDDFA01-6E40-46BB-9F98-9340F4379505@amazon.com
      e3fb6170
    • Michael Paquier's avatar
      Fix backup manifests to generate correct WAL-Ranges across timelines · 65b649fe
      Michael Paquier authored 
      In a backup manifest, WAL-Ranges stores the range of WAL that is
required for the backup to be valid.  pg_verifybackup would then
internally use pg_waldump for the checks based on this data.

When the timeline where the backup started was more than 1 with a
history file looked at for the manifest data generation, the calculation
of the WAL range for the first timeline to check was incorrect.  The
previous logic used as start LSN the start position of the first
timeline, but it needs to use the start LSN of the backup.  This would
cause failures with pg_verifybackup, or any tools making use of the
backup manifests.

This commit adds a test based on a logic using a self-promoted node,
making it rather cheap.

Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/20210818.143031.1867083699202617521.horikyota.ntt@gmail.com
Backpatch-through: 13
      65b649fe
  15. 21 Aug, 2021 1 commit
    • Tom Lane's avatar
      Improve error messages about misuse of SELECT INTO. · 8f6a5219
      Tom Lane authored 
      Improve two places in plpgsql, and one in spi.c, where an error
message would confusingly tell you that you couldn't use a SELECT
query, when what you had written *was* a SELECT query.  The actual
problem is that you can't use SELECT ... INTO in these contexts,
but the messages failed to make that apparent.  Special-case
SELECT INTO to make these errors more helpful.

Also, fix the same spots in plpgsql, as well as several messages
in exec_eval_expr(), to not quote the entire complained-of query or
expression in the primary error message.  That behavior very easily
led to violating our message style guideline about keeping the primary
error message short and single-line.  Also, since the important part
of the message was after the inserted text, it could make the real
problem very hard to see.  We can report the query or expression as
the first line of errcontext instead.

Per complaint from Roger Mason.  Back-patch to v14, since (a) some
of these messages are new in v14 and (b) v14's translatable strings
are still somewhat in flux.  The problem's older than that of
course, but I'm hesitant to change the behavior further back.

Discussion: https://postgr.es/m/1914708.1629474624@sss.pgh.pa.us
      8f6a5219
  17. 20 Aug, 2021 3 commits
  19. 19 Aug, 2021 4 commits
    • Tom Lane's avatar
      Avoid trying to lock OLD/NEW in a rule with FOR UPDATE. · 46490039
      Tom Lane authored 
      transformLockingClause neglected to exclude the pseudo-RTEs for
OLD/NEW when processing a rule's query.  This led to odd errors
or even crashes later on.  This bug is very ancient, but it's
not terribly surprising that nobody noticed, since the use-case
for SELECT FOR UPDATE in a non-view rule is somewhere between
thin and non-existent.  Still, crashing is not OK.

Per bug #17151 from Zhiyong Wu.  Thanks to Masahiko Sawada
for analysis of the problem.

Discussion: https://postgr.es/m/17151-c03a3e6e4ec9aadb@postgresql.org
      46490039
    • Andres Freund's avatar
      Unset MyBEEntry, making elog.c's call to pgstat_get_my_query_id() safe. · 18914f24
      Andres Freund authored 
      Previously log messages late during shutdown could end up using either another
backend's PgBackendStatus (multi user) or segfault (single user) because
pgstat_get_my_query_id()'s check for !MyBEEntry didn't filter out use after
pgstat_beshutdown_hook().

This became a bug in 4f0b0966, but was a bit fishy before. But given
there's no known problematic cases before 14, it doesn't seem worth
backpatching further.

Also fixes a wrong filename in a comment, introduced in e1025044.
Reported-By: default avatarAndres Freund <andres@anarazel.de>
Reviewed-By: default avatarJulien Rouhaud <rjuju123@gmail.com>
Discussion: https://postgr.es/m/Julien Rouhaud <rjuju123@gmail.com>
Backpatch: 14-
      18914f24
    • Amit Kapila's avatar
      Fix typo in protocol.sgml. · e1915646
      Amit Kapila authored 
      The 'Stream Stop' message is misspelled as 'Stream End' in the docs.

Author: Masahiko Sawada
Backpatch-through: 14, where it was introduced
Discussion: https://postgr.es/m/CAD21AoDeScrsHhLyEPYqN3sydg6PxAPVBboK=30xJfUVihNZDA@mail.gmail.com
      e1915646
    • Michael Paquier's avatar
      Revert refactoring of hex code to src/common/ · 1900c140
      Michael Paquier authored 
      This is a combined revert of the following commits:
- c3826f83, a refactoring piece that moved the hex decoding code to
src/common/.  This code was cleaned up by aef8948f, as it originally
included no overflow checks in the same way as the base64 routines in
src/common/ used by SCRAM, making it unsafe for its purpose.
- aef8948f, a more advanced refactoring of the hex encoding/decoding code
to src/common/ that added sanity checks on the result buffer for hex
decoding and encoding.  As reported by Hans Buschmann, those overflow
checks are expensive, and it is possible to see a performance drop in
the decoding/encoding of bytea or LOs the longer they are.  Simple SQLs
working on large bytea values show a clear difference in perf profile.
- ccf4e277, a cleanup made possible by aef8948f.

The reverts of all those commits bring back the performance of hex
decoding and encoding back to what it was in ~13.  Fow now and
post-beta3, this is the simplest option.

Reported-by: Hans Buschmann
Discussion: https://postgr.es/m/1629039545467.80333@nidsa.net
Backpatch-through: 14
      1900c140