Postgres has traditionally considered the syntactic forms f(x) and x.f
to be equivalent, allowing tricks such as writing a function and then
using it as though it were a computed-on-demand column. However, our
behavior when both interpretations are feasible left something to be
desired: we always chose the column interpretation. This could lead
to very surprising results, as in a recent bug report from Neil Conway.
It also created a dump-and-reload hazard, since what was a function
call in a dumped view could get interpreted as a column reference
at reload, if a matching column name had been added to the underlying
table since the view was created.
What seems better, in ambiguous situations, is to prefer the choice
matching the syntactic form of the reference. This seems much less
astonishing in general, and it fixes the dump/reload hazard.
Although this could be called a bug fix, there have been few complaints
and there's some small risk of breaking applications that depend on the
old behavior, so no back-patch. It does seem reasonable to slip it
into v11, though.
Discussion: https://postgr.es/m/CAOW5sYa3Wp7KozCuzjOdw6PiOYPi6D=VvRybtH2S=2C0SVmRmA@mail.gmail.com
On Windows, it is sometimes important for corresponding malloc() and
free() calls to be made from the same DLL, since some build options can
result in multiple allocators being active at the same time. For that
reason we already provided PQfreemem(). This commit adds a similar
function for freeing string results allocated by the pgtypes library.
Author: Takayuki Tsunakawa
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/0A3221C70F24FB45833433255569204D1F8AD5D6%40G01JPEXMBYT05
When a standby's WAL receiver stops reading WAL from a WAL stream, it
writes data to the current WAL segment without having priorily zero'ed
the page currently written to, which can cause the WAL reader to read
junk data from a past recycled segment and then it would try to get a
record from it. While sanity checks in place provide most of the
protection needed, in some rare circumstances, with chances increasing
when a record header crosses a page boundary, then the startup process
could fail violently on an allocation failure, as follows:
FATAL: invalid memory alloc request size XXX
This is confusing for the user and also unhelpful as this requires in
the worst case a manual restart of the instance, impacting potentially
the availability of the cluster, and this also makes WAL data look like
it is in a corrupted state.
The chances of seeing failures are higher if the connection between the
standby and its root node is unstable, causing WAL pages to be written
in the middle. A couple of approaches have been discussed, like
zero-ing new WAL pages within the WAL receiver itself but this has the
disadvantage of impacting performance of any existing instances as this
breaks the sequential writes done by the WAL receiver. This commit
deals with the problem with a more simple approach, which has no
performance impact without reducing the detection of the problem: if a
record is found with a length higher than 1GB for backends, then do not
try any allocation and report a soft failure which will force the
standby to retry reading WAL. It could be possible that the allocation
call passes and that an unnecessary amount of memory is allocated,
however follow-up checks on records would just fail, making this
allocation short-lived anyway.
This patch owes a great deal to Tsunakawa Takayuki for reporting the
failure first, and then discussing a couple of potential approaches to
the problem.
Backpatch down to 9.5, which is where palloc_extended has been
introduced.
Reported-by: Tsunakawa Takayuki
Reviewed-by: Tsunakawa Takayuki
Author: Michael Paquier
Discussion: https://postgr.es/m/0A3221C70F24FB45833433255569204D1F8B57AD@G01JPEXMBYT05
Clean up four places that result in compiler warnings when using recent
gcc with this warning class enabled (as seen on buildfarm members
calliphoridae, skink, and others). In all these places, this is purely
cosmetic, because the shift distance could not be large enough to risk
a change of sign, so there's no chance of implementation-dependent
behavior. Still, it's easy enough to avoid the warning by casting the
shifted value to unsigned, so let's do that.
Patch HEAD only, this isn't worth a back-patch.
gcc 8 has started emitting some warnings that are largely useless for
our purposes, particularly since they complain about code following
the project-standard coding convention that path names are assumed
to be shorter than MAXPGPATH. Even if we make the effort to remove
that assumption in some future release, the changes wouldn't get
back-patched. Hence, just suppress these warnings, on compilers that
have these switches.
Backpatch to all supported branches.
Discussion: https://postgr.es/m/1524563856.26306.9.camel@gunduz.org
Use of strncpy with a length limit based on the source, rather than
the destination, is non-idiomatic and draws warnings from gcc 8.
Replace with memcpy, which does exactly the same thing in these cases,
but with less chance for confusion.
Backpatch to all supported branches.
Discussion: https://postgr.es/m/21789.1529170195@sss.pgh.pa.us
This could only cause an issue if strftime returned a ridiculously
long timezone name, which seems unlikely; and it wouldn't qualify
as a security problem even then, since pg_waldump (nee pg_xlogdump)
is a debug tool not part of the server. But gcc 8 has started issuing
warnings about it, so let's use snprintf and be safe.
Backpatch to 9.3 where this code was added.
Discussion: https://postgr.es/m/21789.1529170195@sss.pgh.pa.us
Recent additions to ParseFuncOrColumn to make it reject non-procedure
functions in CALL were neither adequate nor documented. Reorganize
the code to ensure uniform results for all the cases that should be
rejected. Also, use ERRCODE_WRONG_OBJECT_TYPE for this case as well
as the converse case of a procedure in a non-CALL context. The
original coding used ERRCODE_UNDEFINED_FUNCTION which seems wrong,
and is certainly inconsistent with the adjacent wrong-kind-of-routine
errors.
This reorganization also causes the checks for aggregate decoration with
a non-aggregate function to be made in the FUNCDETAIL_COERCION case;
that they were not is a long-standing oversight.
Discussion: https://postgr.es/m/14497.1529089235@sss.pgh.pa.us
Issues relate only to subtransactions that hold AccessExclusiveLocks
when replayed on standby.
Prior to PG10, aborting subtransactions that held an
AccessExclusiveLock failed to release the lock until top level commit or
abort. 49bff5300d fixed that.
However, 49bff5300d also introduced a similar bug where subtransaction
commit would fail to release an AccessExclusiveLock, leaving the lock to
be removed sometimes early and sometimes late. This commit fixes
that bug also. Backpatch to PG10 needed.
Tested by observation. Note need for multi-node isolationtester to improve
test coverage for this and other HS cases.
Reported-by: Simon Riggs
Author: Simon Riggs
Also this commit unifies some duplicated code in makeBufFile() and
BufFileOpenShared() into new function makeBufFileCommon().
Author: Antonin Houska
Reviewed-By: Thomas Munro, Tatsuo Ishii
Discussion: https://postgr.es/m/16139.1529049566%40localhost
PyObject returned from PySequence_GetItem() is not released. Similar code in PLyMapping_ToJsonbValue() is correct, because according to Python documentation
PyList_GetItem() and PyTuple_GetItem() return a borrowed reference while
PySequence_GetItem() returns new reference. contrib/jsonb_plpython is new
in PostgreSQL 11, no backpatch is needed.
Author: Nikita Glukhov
Discussion: https://postgr.es/m/6001af16-b242-2527-bc7e-84b8a959163b%40postgrespro.ru
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
GetRunningTransactionData() suggested that subxids were not worth
optimizing away if overflowed, yet they have already been removed
for that case.
Changes to LogAccessExclusiveLock() API forgot to remove the
prior comment when it was copied to LockAcquire().
32ac7a118f tried to fix a Hot Standby issue
reported by Greg Stark, but in doing so caused
a different bug to appear, noted by Andres Freund.
Revoke the core changes from 32ac7a118f,
leaving in its place a minor change in code
ordering and comments to explain for the future.
Fix inconsistent decisions about NOMATCH vs UNSUPPORTED result codes.
If we're going to cater for partkeys that have the same expression and
different collations, surely we should also support partkeys with the
same expression and different opclasses.
Clean up shaky handling of commuted opclauses, eg checking the wrong
operator to see what its negator is. This wouldn't cause any actual
bugs given a sane opclass definition, but it doesn't seem helpful to
expend more code to be less correct.
Improve handling of null elements in ScalarArrayOp arrays: in the
"op ALL" case, we can conclude they result in an unsatisfiable clause.
Minor cosmetic changes and comment improvements.
The previous coding saved pointers into the partitioned table's relcache
entry, but then closed the relcache entry, causing those pointers to
nominally become dangling. Actual trouble would be seen in the field
only if a relcache flush occurred mid-query, but that's hardly out of
the question.
While we could fix this by copying all the data in question at query
start, it seems better to just hold the relcache entry open for the
whole query.
While at it, improve the handling of support-function lookups: do that
once per query not once per pruning test. There's still something to be
desired here, in that we fail to exploit the possibility of caching data
across queries in the fn_extra fields of the relcache's FmgrInfo structs,
which could happen if we just used those structs in-place rather than
copying them. However, combining that with the possibility of per-query
lookups of cross-type comparison functions seems to require changes in the
APIs of a lot of the pruning support functions, so it's too invasive to
consider as part of this patch. A win would ensue only for complex
partition key data types (e.g. arrays), so it may not be worth the
trouble.
David Rowley and Tom Lane
Discussion: https://postgr.es/m/17850.1528755844@sss.pgh.pa.us
Documentation of word_similarity() and strict_word_similarity() functions
contains some vague wordings which could confuse users. This patch makes
those wordings more clear. word_similarity() was introduced in PostgreSQL 9.6,
and corresponding part of documentation needs to be backpatched.
Author: Bruce Momjian, Alexander Korotkov
Discussion: https://postgr.es/m/20180526165648.GB12510%40momjian.us
Backpatch: 9.6, where word_similarity() was introduced
The .git directory might contain perl files, as hooks, for example.
Since we have no control over these they should be excluded from things
like our perlcritic checks.
Per offline report from Mike Blackwell.
When vacuum processes a relation it uses the corresponding relcache
entry's relfrozenxid / relminmxid as a cutoff for when to remove
tuples etc. Unfortunately for nailed relations (i.e. critical system
catalogs) bugs could frequently lead to the corresponding relcache
entry being stale.
This set of bugs could cause actual data corruption as vacuum would
potentially not remove the correct row versions, potentially reviving
them at a later point. After 699bf7d05c some corruptions in this vein
were prevented, but the additional error checks could also trigger
spuriously. Examples of such errors are:
ERROR: found xmin ... from before relfrozenxid ...
and
ERROR: found multixact ... from before relminmxid ...
To be caused by this bug the errors have to occur on system catalog
tables.
The two bugs are:
1) Invalidations for nailed relations were ignored, based on the
theory that the relcache entry for such tables doesn't
change. Which is largely true, except for fields like relfrozenxid
etc. This means that changes to relations vacuumed in other
sessions weren't picked up by already existing sessions. Luckily
autovacuum doesn't have particularly longrunning sessions.
2) For shared *and* nailed relations, the shared relcache init file
was never invalidated while running. That means that for such
tables (e.g. pg_authid, pg_database) it's not just already existing
sessions that are affected, but even new connections are as well.
That explains why the reports usually were about pg_authid et. al.
To fix 1), revalidate the rd_rel portion of a relcache entry when
invalid. This implies a bit of extra complexity to deal with
bootstrapping, but it's not too bad. The fix for 2) is simpler,
simply always remove both the shared and local init files.
Author: Andres Freund
Reviewed-By: Alvaro Herrera
Discussion:
https://postgr.es/m/20180525203736.crkbg36muzxrjj5e@alap3.anarazel.dehttps://postgr.es/m/CAMa1XUhKSJd98JW4o9StWPrfS=11bPgG+_GDMxe25TvUY4Sugg@mail.gmail.comhttps://postgr.es/m/CAKMFJucqbuoDRfxPDX39WhA3vJyxweRg_zDVXzncr6+5wOguWA@mail.gmail.comhttps://postgr.es/m/CAGewt-ujGpMLQ09gXcUFMZaZsGJC98VXHEFbF-tpPB0fB13K+A@mail.gmail.com
Backpatch: 9.3-
It might be impossible for this to cause a problem in non-debug builds,
since there'd be no opportunity for the relcache entry to get recycled
before the fetch. It blows up nicely with -DRELCACHE_FORCE_RELEASE plus
valgrind, though.
Evidently introduced by careless refactoring in commit f0e44751d.
Back-patch accordingly.
Discussion: https://postgr.es/m/27543.1528758304@sss.pgh.pa.us
Calling an external function while a pin-lock is held is a bad idea as
those are designed to be short-lived. The stress of a first commit into
a large git history may contribute to that.
Reported-by: Andres Freund
Discussion: https://postgr.es/m/20180611164952.vmxdpdpirdtkdsz6@alap3.anarazel.de
We don't need two passes if we scan child partitions before parents,
as that way the children's present_parts are up to date before they're
needed. I (tgl) think there's actually a bug being fixed here, for the
case of an intermediate partitioned table with no direct leaf children,
but haven't attempted to construct a test case to prove it.
David Rowley
Discussion: https://postgr.es/m/CAKJS1f-6GODRNgEtdPxCnAPme2h2hTztB6LmtfdmcYAAOE0kQg@mail.gmail.com
Starting with commit f0e44751d7, ExecConstraints was in charge of
running the partition constraint; commit 19c47e7c82 modified that so
that caller could request to skip that checking depending on some
conditions, but that commit and 15ce775faa together introduced a small
bug there which caused ExecInsert to request skipping the constraint
check but have this not be honored -- in effect doing the check twice.
This could have been fixed in a very small patch, but on further
analysis of the involved function and its callsites, it turns out to be
simpler to give the responsibility of checking the partition constraint
fully to the caller, and return ExecConstraints to its original
(pre-partitioning) shape where it only checked tuple descriptor-related
constraints. Each caller must do partition constraint checking on its
own schedule, which is more convenient after commit 2f17844104 anyway.
Reported-by: David Rowley
Author: David Rowley, Álvaro Herrera
Reviewed-by: Amit Langote, Amit Khandekar, Simon Riggs
Discussion: https://postgr.es/m/CAKJS1f8w8+awsxgea8wt7_UX8qzOQ=Tm1LD+U1fHqBAkXxkW2w@mail.gmail.com
Also add a function that centralizes the logic for locating all our perl
files and use it in pgperlcritic and pgperltidy as well as the new
pgperlcheck.
The previous coding just ignored pruning constraints that compare a
partition key to a null-valued expression. This is silly, since really
what we can do there is conclude that all partitions are rejected: the
pruning operator is known strict so the comparison must always fail.
This also fixes the logic to not ignore constisnull for a Const comparison
value. That's probably an unreachable case, since the planner would
normally have simplified away a strict operator with a constant-null input.
But this code has no business assuming that.
David Rowley, per a gripe from me
Discussion: https://postgr.es/m/26279.1528670981@sss.pgh.pa.us
A review of the code has showed up a couple of issues fixed by this
commit:
- Physical slots have been using the confirmed LSN position as a start
comparison point which is always 0/0, instead use the restart LSN
position (logical slots need to use the confirmed LSN position, which
was correct).
- The actual slot update was incorrect for both physical and logical
slots. Physical slots need to use their restart_lsn as base comparison
point (confirmed_flush was used because of previous point), and logical
slots need to begin reading WAL from restart_lsn (confirmed_flush was
used as well), while confirmed_flush is compiled depending on the
decoding context and record read, and is the LSN position returned back
to the caller.
- Never return 0/0 if a slot cannot be advanced. This way, if a slot is
advanced while the activity is idle, then the same position is returned
to the caller over and over without raising an error. Instead return
the LSN the slot has been advanced to. With repetitive calls, the same
position is returned hence caller can directly monitor the difference in
progress in bytes by doing simply LSN difference calculations, which
should be monotonic.
Note that as the slot is owned by the backend advancing it, then the
read of those fields is fine lock-less, while updates need to happen
while the slot mutex is held, so fix that on the way as well. Other
locks for in-memory data of replication slots have been already fixed
previously.
Some of those issues have been pointed out by Petr and Simon during the
patch, while I noticed some of them after looking at the code. This
also visibly takes of a recently-discovered bug causing assertion
failures which can be triggered by a two-step slot forwarding which
first advanced the slot to a WAL page boundary and secondly advanced it
to the latest position, say 'FF/FFFFFFF' to make sure that the newest
LSN is used as forward point. It would have been nice to drop a test
for that, but the set of operators working on pg_lsn limits it, so this
is left for a future exercise.
Author: Michael Paquier
Reviewed-by: Petr Jelinek, Simon Riggs
Discussion: https://postgr.es/m/CANP8+jLyS=X-CAk59BJnsxKQfjwrmKicHQykyn52Qj-Q=9GLCw@mail.gmail.com
Discussion: https://www.postgresql.org/message-id/2840048a-1184-417a-9da8-3299d207a1d7%40postgrespro.ru
These struct definitions were originally dropped into primnodes.h,
which is a poor choice since that's mainly intended for primitive
expression node types; these are not in that category. What they
are is auxiliary info in Plan trees, so move them to plannodes.h.
For consistency, also relocate some related code that was apparently
placed with the aid of a dartboard.
There's no interesting code changes in this commit, just reshuffling.
David Rowley and Tom Lane
Discussion: https://postgr.es/m/CAFj8pRBjrufA3ocDm8o4LPGNye9Y+pm1b9kCwode4X04CULG3g@mail.gmail.com
The initial coding of the run-time-pruning feature only coped with cases
where the partition key(s) are compared to Params. That is a bit silly;
we can allow it to work with any non-Var-containing stable expression, as
long as we take special care with expressions containing PARAM_EXEC Params.
The code is hardly any longer this way, and it's considerably clearer
(IMO at least). Per gripe from Pavel Stehule.
David Rowley, whacked around a bit by me
Discussion: https://postgr.es/m/CAFj8pRBjrufA3ocDm8o4LPGNye9Y+pm1b9kCwode4X04CULG3g@mail.gmail.com
While debugging issues on HEAD for the new slot forwarding feature of
Postgres 11, some monitoring of the code surrounding in-memory slot data
has proved that the lock handling may cause inconsistent data to be read
by read-only callers of slot functions, particularly
pg_get_replication_slots() which fetches data for the system view
pg_replication_slots, or modules looking directly at slot information.
The code paths involved in those problems concern logical decoding
initialization (down to 9.4) and WAL reservation for slots (new as of
10).
A set of comments documenting all the lock handlings, particularly the
dependency with LW locks for slots and the in_use flag as well as the
internal mutex lock is added, based on a suggested by Simon Riggs.
Some of the fixed code exists down to 9.4 where WAL decoding has been
introduced, but as those race conditions are really unlikely going to
happen as those concern code paths for slot and decoding creation, just
fix the problem on HEAD.
Author: Michael Paquier
Discussion: https://postgr.es/m/20180528085747.GA27845@paquier.xyz
Make sure that we don't exceed MaxAllocSize when increasing the number of
buckets. Perhaps later we'll remove that limit and use DSA_ALLOC_HUGE, but
for now just prevent further increases like the non-parallel code. This
change avoids the error from bug report #15225.
Author: Thomas Munro
Reviewed-By: Tom Lane
Reported-by: Frits Jalvingh
Discussion: https://postgr.es/m/152802081668.26724.16985037679312485972%40wrigleys.postgresql.org
Also, fix the pg_settings view to display source filename and line
number when invoked by a pg_read_all_settings member. This addition by
me (Álvaro).
Also, fix wording of the comment in GetConfigOption regarding the
restriction it implements, renaming the parameter for extra clarity.
Noted by Michaël.
These were all oversight in commit 25fff40798fc; backpatch to pg10,
where that commit first appeared.
Author: Laurenz Albe
Reviewed-by: Michaël Paquier, Álvaro Herrera
Discussion: https://postgr.es/m/1519917758.6586.8.camel@cybertec.at
Tom Lane
Thomas Munro
Michael Paquier
Peter Geoghegan
Simon Riggs
Tatsuo Ishii
Alvaro Herrera
Alexander Korotkov
Andrew Dunstan
Andres Freund
Peter Eisentraut