The ability to create like-named objects in different schemas opens up
the potential for users to change the behavior of other users' queries,
maliciously or accidentally. When you connect to a PostgreSQL server,
you should remove from your search_path any schema for which a user
other than yourself or superusers holds the CREATE privilege. If you do
not, other users holding CREATE privilege can redefine the behavior of
your commands, causing them to perform arbitrary SQL statements under
your identity. "SET search_path = ..." and "SELECT
pg_catalog.set_config(...)" are not vulnerable to such hijacking, so one
can use either as the first command of a session. As special
exceptions, the following client applications behave as documented
regardless of search_path settings and schema privileges: clusterdb
createdb createlang createuser dropdb droplang dropuser ecpg (not
programs it generates) initdb oid2name pg_archivecleanup pg_basebackup
pg_config pg_controldata pg_ctl pg_dump pg_dumpall pg_isready
pg_receivewal pg_recvlogical pg_resetwal pg_restore pg_rewind pg_standby
pg_test_fsync pg_test_timing pg_upgrade pg_waldump reindexdb vacuumdb
vacuumlo. Not included are core client programs that run user-specified
SQL commands, namely psql and pgbench. PostgreSQL encourages non-core
client applications to do likewise.
Document this in the context of libpq connections, psql connections,
dblink connections, ECPG connections, extension packaging, and schema
usage patterns. The principal defense for applications is "SELECT
pg_catalog.set_config('search_path', '', false)", and the principal
defense for databases is "REVOKE CREATE ON SCHEMA public FROM PUBLIC".
Either one is sufficient to prevent attack. After a REVOKE, consider
auditing the public schema for objects named like pg_catalog objects.
Authors of SECURITY DEFINER functions use some of the same defenses, and
the CREATE FUNCTION reference page already covered them thoroughly.
This is a good opportunity to audit SECURITY DEFINER functions for
robust security practice.
Back-patch to 9.3 (all supported versions).
Reviewed by Michael Paquier and Jonathan S. Katz. Reported by Arseniy
Sharoglazov.
Security: CVE-2018-1058
This makes the client programs behave as documented regardless of the
connect-time search_path and regardless of user-created objects. Today,
a malicious user with CREATE permission on a search_path schema can take
control of certain of these clients' queries and invoke arbitrary SQL
functions under the client identity, often a superuser. This is
exploitable in the default configuration, where all users have CREATE
privilege on schema "public".
This changes behavior of user-defined code stored in the database, like
pg_index.indexprs and pg_extension_config_dump(). If they reach code
bearing unqualified names, "does not exist" or "no schema has been
selected to create in" errors might appear. Users may fix such errors
by schema-qualifying affected names. After upgrading, consider watching
server logs for these errors.
The --table arguments of src/bin/scripts clients have been lax; for
example, "vacuumdb -Zt pg_am\;CHECKPOINT" performed a checkpoint. That
now fails, but for now, "vacuumdb -Zt 'pg_am(amname);CHECKPOINT'" still
performs a checkpoint.
Back-patch to 9.3 (all supported versions).
Reviewed by Tom Lane, though this fix strategy was not his first choice.
Reported by Arseniy Sharoglazov.
Security: CVE-2018-1058
Historically, pg_dump has "set search_path = foo, pg_catalog" when
dumping an object in schema "foo", and has also caused that setting
to be used while restoring the object. This is problematic because
functions and operators in schema "foo" could capture references meant
to refer to pg_catalog entries, both in the queries issued by pg_dump
and those issued during the subsequent restore run. That could
result in dump/restore misbehavior, or in privilege escalation if a
nefarious user installs trojan-horse functions or operators.
This patch changes pg_dump so that it does not change the search_path
dynamically. The emitted restore script sets the search_path to what
was used at dump time, and then leaves it alone thereafter. Created
objects are placed in the correct schema, regardless of the active
search_path, by dint of schema-qualifying their names in the CREATE
commands, as well as in subsequent ALTER and ALTER-like commands.
Since this change requires a change in the behavior of pg_restore
when processing an archive file made according to this new convention,
bump the archive file version number; old versions of pg_restore will
therefore refuse to process files made with new versions of pg_dump.
Security: CVE-2018-1058
The previous limit of INT_MAX / 1000 seems to have been cargo-culted in
from somewhere else. Or possibly the value was converted to microseconds
at some point; but in all supported releases, it's just compared to other
values, so there's no need for the restriction. This change raises the
effective limit from ~35 minutes to ~24 days, which conceivably is useful
to somebody, and anyway it's more consistent with the range of the core
log_min_duration_statement GUC.
Per complaint from Kevin Bloch. Back-patch to all supported releases.
Discussion: https://postgr.es/m/8ea82d7e-cb78-8e05-0629-73aa14d2a0ca@codingthat.com
This is mostly cosmetic, but it might fix build failures, on some
platform, when copying from the documentation.
Back-patch to 9.3 (all supported versions).
Given overlapping or partially redundant join clauses, for example
t1 JOIN t2 ON t1.a = t2.x AND t1.b = t2.x
the planner's EquivalenceClass machinery will ordinarily refactor the
clauses as "t1.a = t1.b AND t1.a = t2.x", so that join processing doesn't
see multiple references to the same EquivalenceClass in a list of join
equality clauses. However, if the join is outer, it's incorrect to derive
a restriction clause on the outer side from the join conditions, so the
clause refactoring does not happen and we end up with overlapping join
conditions. The code that attempted to deal with such cases had several
subtle bugs, which could result in "left and right pathkeys do not match in
mergejoin" or "outer pathkeys do not match mergeclauses" planner errors,
if the selected join plan type was a mergejoin. (It does not appear that
any actually incorrect plan could have been emitted.)
The core of the problem really was failure to recognize that the outer and
inner relations' pathkeys have different relationships to the mergeclause
list. A join's mergeclause list is constructed by reference to the outer
pathkeys, so it will always be ordered the same as the outer pathkeys, but
this cannot be presumed true for the inner pathkeys. If the inner sides of
the mergeclauses contain multiple references to the same EquivalenceClass
({t2.x} in the above example) then a simplistic rendering of the required
inner sort order is like "ORDER BY t2.x, t2.x", but the pathkey machinery
recognizes that the second sort column is redundant and throws it away.
The mergejoin planning code failed to account for that behavior properly.
One error was to try to generate cut-down versions of the mergeclause list
from cut-down versions of the inner pathkeys in the same way as the initial
construction of the mergeclause list from the outer pathkeys was done; this
could lead to choosing a mergeclause list that fails to match the outer
pathkeys. The other problem was that the pathkey cross-checking code in
create_mergejoin_plan treated the inner and outer pathkey lists
identically, whereas actually the expectations for them must be different.
That led to false "pathkeys do not match" failures in some cases, and in
principle could have led to failure to detect bogus plans in other cases,
though there is no indication that such bogus plans could be generated.
Reported by Alexander Kuzmenkov, who also reviewed this patch. This has
been broken for years (back to around 8.3 according to my testing), so
back-patch to all supported branches.
Discussion: https://postgr.es/m/5dad9160-4632-0e47-e120-8e2082000c01@postgrespro.ru
This backpatches 935dee9ad5a8d12f4d3b772a6e6c99d245e5ad44 to the
the branches requested by extension authors.
Original-Author: Metin Doslu
Original-Committer: Robert Haas
Author: Brian Cloutier
This oversight led to data corruption in matviews, manifesting as
"could not access status of transaction" before our most recent releases,
and "found xmin from before relfrozenxid" errors since then.
The proximate cause of the problem seems to have been confusion between
the task of preserving dropped-column status and the task of preserving
frozenxid status. Those are required for distinct sets of relkinds,
and the reasoning was entirely undocumented in the source code. In hopes
of forestalling future errors of the same kind, try to improve the
commentary in this area.
In passing, also improve the remarkably unhelpful comments around
pg_upgrade's set_frozenxids(). That's not actually buggy AFAICS,
but good luck figuring out what it does from the old comments.
Per report from Claudio Freire. It appears that bug #14852 from Alexey
Ermakov is an earlier report of the same issue, and there may be other
cases that we failed to identify at the time.
Patch by me based on analysis by Andres Freund. The bug dates back
to the introduction of matviews, so back-patch to all supported branches.
Discussion: https://postgr.es/m/CAGTBQpbrY9CdRGGhyBZ9yqY4jWaGC85rUF4X+R7d-aim=mBNsw@mail.gmail.com
Discussion: https://postgr.es/m/20171013115320.28049.86457@wrigleys.postgresql.org
An updating query that reads a CTE within an InitPlan or SubPlan could get
incorrect results if it updates rows that are concurrently being modified.
This is caused by CteScanNext supposing that nothing inside its recursive
ExecProcNode call could change which read pointer is selected in the CTE's
shared tuplestore. While that's normally true because of scoping
considerations, it can break down if an EPQ plan tree gets built during the
call, because EvalPlanQualStart builds execution trees for all subplans
whether they're going to be used during the recheck or not. And it seems
like a pretty shaky assumption anyway, so let's just reselect our own read
pointer here.
Per bug #14870 from Andrei Gorita. This has been broken since CTEs were
implemented, so back-patch to all supported branches.
Discussion: https://postgr.es/m/20171024155358.1471.82377@wrigleys.postgresql.org
plpython_error_callback() reported the name of the function associated
with the topmost PL/Python execution context. This was not merely
wrong if there were nested PL/Python contexts, but it risked a core
dump if the topmost one is an inline code block rather than a named
function. That will have proname = NULL, and so we were passing a NULL
pointer to snprintf("%s"). It seems that none of the PL/Python-testing
machines in the buildfarm will dump core for that, but some platforms do,
as reported by Marina Polyakova.
Investigation finds that there actually is an existing regression test
that used to prove that the behavior was wrong, though apparently no one
had noticed that it was printing the wrong function name. It stopped
showing the problem in 9.6 when we adjusted psql to not print CONTEXT
by default for NOTICE messages. The problem is masked (if your platform
avoids the core dump) in error cases, because PL/Python will throw away
the originally generated error info in favor of a new traceback produced
at the outer level.
Repair by using ErrorContextCallback.arg to pass the correct context to
the error callback. Add a regression test illustrating correct behavior.
Back-patch to all supported branches, since they're all broken this way.
Discussion: https://postgr.es/m/156b989dbc6fe7c4d3223cf51da61195@postgrespro.ru
Since we now support the server side handler for git over https (so
we're no longer using the "dumb protocol"), make https the primary
choice for cloning the repository, and the git protocol the secondary
choice.
In passing, also change the links to git-scm.com from http to https.
Reviewed by Stefan Kaltenbrunner and David G. Johnston
pg_upgrade has always attempted to ensure that the transient dump files
it creates are inaccessible except to the owner. However, refactoring
in commit 76a7650c4 broke that for the file containing "pg_dumpall -g"
output; since then, that file was protected according to the process's
default umask. Since that file may contain role passwords (hopefully
encrypted, but passwords nonetheless), this is a particularly unfortunate
oversight. Prudent users of pg_upgrade on multiuser systems would
probably run it under a umask tight enough that the issue is moot, but
perhaps some users are depending only on pg_upgrade's umask changes to
protect their data.
To fix this in a future-proof way, let's just tighten the umask at
process start. There are no files pg_upgrade needs to write at a
weaker security level; and if there were, transiently relaxing the
umask around where they're created would be a safer approach.
Report and patch by Tom Lane; the idea for the fix is due to Noah Misch.
Back-patch to all supported branches.
Security: CVE-2018-1053
Commit 9521ce4a7a1125385fb4de9689f345db594c516a from Sep 13, 2017 and
backpatched through 9.5 used rsync examples with datadir. The reporter
has pointed out, and testing has verified, that clusterdir must be used,
so update the docs accordingly.
Reported-by: Don Seiler
Discussion: https://postgr.es/m/CAHJZqBD0u9dCERpYzK6BkRv=663AmH==DFJpVC=M4Xg_rq2=CQ@mail.gmail.com
Backpatch-through: 9.5
Commit 4bbf6edfbd5d03743ff82dda2f00c738fb3208f5 added a test case,
but it turns out that the test case doesn't reliably test for the
bug, and in the context of the regression test suite did not because
ANALYZE had not been run.
Report and patch by Etsuro Fujita. I added a comment along lines
previously suggested by Tom Lane.
Discussion: http://postgr.es/m/5A6195D8.8060206@lab.ntt.co.jp
create_plan_recurse lacked any stack depth check. This is not per
our normal coding rules, but I'd supposed it was safe because earlier
planner processing is more complex and presumably should eat more
stack. But bug #15033 from Andrew Grossman shows this isn't true,
at least not for queries having the form of a many-thousand-way
INTERSECT stack.
Further testing showed that recurse_set_operations is also capable
of being crashed in this way, since it likewise will recurse to the
bottom of a parsetree before calling any support functions that
might themselves contain any stack checks. However, its stack
consumption is only perhaps a third of create_plan_recurse's.
It's possible that this particular problem with create_plan_recurse can
only manifest in 9.6 and later, since before that we didn't build a Path
tree for set operations. But having seen this example, I now have no
faith in the proposition that create_plan_recurse doesn't need a stack
check, so back-patch to all supported branches.
Discussion: https://postgr.es/m/20180127050845.28812.58244@wrigleys.postgresql.org
DST law changes in Brazil, Sao Tome and Principe. Historical corrections
for Bolivia, Japan, and South Sudan. The "US/Pacific-New" zone has been
removed (it was only a link to America/Los_Angeles anyway).
If we're inside a lateral subquery, there may be no unparameterized paths
for a particular child relation of an appendrel, in which case we *must*
be able to create similarly-parameterized paths for each other child
relation, else the planner will fail with "could not devise a query plan
for the given query". This means that there are situations where we'd
better be able to reparameterize at least one path for each child.
This calls into question the assumption in reparameterize_path() that
it can just punt if it feels like it. However, the only case that is
known broken right now is where the child is itself an appendrel so that
all its paths are AppendPaths. (I think possibly I disregarded that in
the original coding on the theory that nested appendrels would get folded
together --- but that only happens *after* reparameterize_path(), so it's
not excused from handling a child AppendPath.) Given that this code's been
like this since 9.3 when LATERAL was introduced, it seems likely we'd have
heard of other cases by now if there were a larger problem.
Per report from Elvis Pranskevichus. Back-patch to 9.3.
Discussion: https://postgr.es/m/5981018.zdth1YWmNy@hammer.magicstack.net
Commit 28724fd90d2f85a0573a8107b48abad062a86d83 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
_tocEntryRequired() expects that it can identify ACL, SECURITY LABEL,
and COMMENT TOC entries that are for large objects by seeing whether
the tag for them starts with "LARGE OBJECT ". While that works fine
for actual large objects, which are indeed tagged that way, it's
subject to false positives unless every such entry's tag starts with an
appropriate type ID. And in fact it does not work for ACLs, because
up to now we customarily tagged those entries with just the bare name
of the object. This means that an ACL for an object named
"LARGE OBJECT something" would be misclassified as data not schema,
with undesirable results in a schema-only or data-only dump ---
although pg_upgrade seems unaffected, due to the special case for
binary-upgrade mode further down in _tocEntryRequired().
We can fix this by changing all the dumpACL calls to use the label
strings already in use for comments and security labels, which do
follow the convention of starting with an object type indicator.
Well, mostly they follow it. dumpDatabase() got it wrong, using
just the bare database name for those purposes, so that a database
named "LARGE OBJECT something" would similarly be subject to having
its comment or security label dropped or included when not wanted.
Bring that into line too. (Note that up to now, database ACLs have
not been processed by pg_dump, so that this issue doesn't affect them.)
_tocEntryRequired() itself is not free of fault: it was overly liberal
about matching object tags to "LARGE OBJECT " in binary-upgrade mode.
This looks like it is probably harmless because there would be no data
component to strip anyway in that mode, but at best it's trouble
waiting to happen, so tighten that up too.
The possible misclassification of SECURITY LABEL entries for databases is
in principle a security problem, but the opportunities for actual exploits
seem too narrow to be interesting. The other cases seem like just bugs,
since an object owner can change its ACL or comment for himself, he needn't
try to trick someone else into doing it by choosing a strange name.
This has been broken since per-large-object TOC entries were introduced
in 9.0, so back-patch to all supported branches.
Discussion: https://postgr.es/m/21714.1516553459@sss.pgh.pa.us
Document how to properly create root and intermediate certificates using
v3_ca extensions and where to place intermediate certificates so they
are properly transferred to the remote side with the leaf certificate to
link to the remote root certificate. This corrects docs that used to
say that intermediate certificates must be stored with the root
certificate.
Also add instructions on how to create root, intermediate, and leaf
certificates.
Discussion: https://postgr.es/m/20180116002238.GC12724@momjian.us
Reviewed-by: Michael Paquier
Backpatch-through: 9.3
For no apparent reason, this function was using a 16bit-wide inhseqno
value, rather than the correct 32 bit width which is what is stored in
the pg_inherits catalog. This becomes evident if you try to create a
table with more than 65535 parents, because this error appears:
ERROR: duplicate key value violates unique constraint «pg_inherits_relid_seqno_index»
DETAIL: Key (inhrelid, inhseqno)=(329371, 0) already exists.
Needless to say, having so many parents is an uncommon situations, which
explains why this error has never been reported despite being having
been introduced with the Postgres95 1.01 sources in commit d31084e9d111:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/commands/creatinh.c;hb=d31084e9d111#l349
Backpatch all the way back.
David Rowley noticed this while reviewing a patch of mine.
Discussion: https://postgr.es/m/CAKJS1f8Dn7swSEhOWwzZzssW7747YB=2Hi+T7uGud40dur69-g@mail.gmail.com
On Sparc64, use of __attribute__(aligned(8)) with __int128 causes faulty
code generation in gcc versions at least through 5.5.0. We can work around
that by disabling use of __int128, so teach configure to test for the bug.
This solution doesn't fix things for the case of cross-compiling with a
buggy compiler; to support that nicely, we'd need to add a manual disable
switch. Unless more such cases turn up, it doesn't seem worth the work.
Affected users could always edit pg_config.h manually.
In passing, fix some typos in the existing configure test for __int128.
They're harmless because we only compile that code not run it, but
they're still confusing for anyone looking at it closely.
This is needed in support of commit 751804998, so back-patch to 9.5
as that was.
Marina Polyakova, Victor Wagner, Tom Lane
Discussion: https://postgr.es/m/0d3a9fa264cebe1cb9966f37b7c06e86@postgrespro.ru
When pushing down a join to a foreign server, postgres_fdw constructs
an alternative plan to be used for any EvalPlanQual rechecks that
prove to be necessary. This plan is stored as the outer subplan of
the Foreign Scan implementing the pushed-down join. Previously, this
alternative plan could have a different nominal sort ordering than its
parent, which seemed OK since there will only be one tuple per base
table anyway in the case of an EvalPlanQual recheck. Actually,
though, it caused a problem if that path was used as a building block
for the EvalPlanQual recheck plan of a higher-level foreign join,
because we could end up with a merge join one of whose inputs was not
labelled with the correct sort order. Repair by injecting an extra
Sort node into the EvalPlanQual recheck plan whenever it would
otherwise fail to be sorted at least as well as its parent Foreign
Scan.
Report by Jeff Janes. Patch by me, reviewed by Tom Lane, who also
provided the test case and comment text.
Discussion: http://postgr.es/m/CAMkU=1y2G8VOVBHv3iXU2TMAj7-RyBFFW1uhkr5sm9LQ2=X35g@mail.gmail.com
If a query against an inheritance tree runs concurrently with an ALTER
TABLE that's disinheriting one of the tree members, it's possible to get
a "could not find inherited attribute" error because after obtaining lock
on the removed member, make_inh_translation_list sees that its columns
have attinhcount=0 and decides they aren't the columns it's looking for.
An ideal fix, perhaps, would avoid including such a just-removed member
table in the query at all; but there seems no way to accomplish that
without adding expensive catalog rechecks or creating a likelihood of
deadlocks. Instead, let's just drop the check on attinhcount. In this
way, a query that's included a just-disinherited child will still
succeed, which is not a completely unreasonable behavior.
This problem has existed for a long time, so back-patch to all supported
branches. Also add an isolation test verifying related behaviors.
Patch by me; the new isolation test is based on Kyotaro Horiguchi's work.
Discussion: https://postgr.es/m/20170626.174612.23936762.horiguchi.kyotaro@lab.ntt.co.jp
If we flatten a subquery whose target list contains constants or
expressions, when those output columns are used in GROUPING SET columns,
the planner was capable of doing the wrong thing by merging a pulled-up
expression into the surrounding expression during const-simplification.
Then the late processing that attempts to match subexpressions to grouping
sets would fail to match those subexpressions to grouping sets, with the
effect that they'd not go to null when expected.
To fix, wrap such subquery outputs in PlaceHolderVars, ensuring that
they preserve their separate identity throughout the planner's expression
processing. This is a bit of a band-aid, because the wrapper defeats
const-simplification even in places where it would be safe to allow.
But a nicer fix would likely be too invasive to back-patch, and the
consequences of the missed optimizations probably aren't large in most
cases.
Back-patch to 9.5 where grouping sets were introduced.
Heikki Linnakangas, with small mods and better test cases by me;
additional review by Andrew Gierth
Discussion: https://postgr.es/m/7dbdcf5c-b5a6-ef89-4958-da212fe10176@iki.fi
~> (cube, int) operator was especially designed for knn-gist search.
However, it appears that knn-gist search can't work correctly with current
behavior of this operator when dataset contains cubes of variable
dimensionality. In this case, the same value of second operator argument
can point to different dimension depending on dimensionality of particular cube.
Such behavior is incompatible with gist indexing of cubes, and knn-gist doesn't
work correctly for it.
This patch changes behavior of ~> (cube, int) operator by introducing dimension
numbering where value of second argument unambiguously identifies number of
dimension. With new behavior, this operator can be correctly supported by
knn-gist. Relevant changes to cube operator class are also included.
Backpatch to v9.6 where operator was introduced.
Since behavior of ~> (cube, int) operator is changed, depending entities
must be refreshed after upgrade. Such as, expression indexes using this
operator must be reindexed, materialized views must be rebuilt, stored
procedures and client code must be revised to correctly use new behavior.
That should be mentioned in release notes.
Noticed by: Tomas Vondra
Author: Alexander Korotkov
Reviewed by: Tomas Vondra, Andrey Borodin
Discussion: https://www.postgresql.org/message-id/flat/a9657f6a-b497-36ff-e56-482a2c7e3292@2ndquadrant.com
These functions are stated to be Oracle-compatible, but they weren't.
Yugo Nagata noticed that while our code returns zero for a zero or
negative fourth parameter (occur_index), Oracle throws an error.
Further testing by me showed that there was also a discrepancy in the
interpretation of a negative third parameter (beg_index): Oracle thinks
that a negative beg_index indicates the last place where the target
substring can *begin*, whereas our code thinks it is the last place
where the target can *end*.
Adjust the sample code to behave like Oracle in both these respects.
Also change it to be a CDATA[] section, simplifying copying-and-pasting
out of the documentation source file. And fix minor problems in the
introductory comment, which wasn't very complete or accurate.
Back-patch to all supported branches. Although this patch only touches
documentation, we should probably call it out as a bug fix in the next
minor release notes, since users who have adopted the functions will
likely want to update their versions.
Yugo Nagata and Tom Lane
Discussion: https://postgr.es/m/20171229191705.c0b43a8c.nagata@sraoss.co.jp
It seems incorrect to assume that the list of CkptSortItems can never
contain duplicate page numbers: concurrent activity could result in some
page getting dropped from a low-numbered buffer and later loaded into a
high-numbered buffer while BufferSync is scanning the buffer pool.
If that happened, the comparator would give self-inconsistent results,
potentially confusing qsort(). Saving one comparison step is not worth
possibly getting the sort wrong.
So far as I can tell, nothing would actually go wrong given our current
implementation of qsort(). It might get a bit slower than expected
if there were a large number of duplicates of one value, but that's
surely a probability-epsilon case. Still, the comment is wrong,
and if we ever switched to another sort implementation it might be
less forgiving.
In passing, avoid casting away const-ness of the argument pointers;
I've not seen any compiler complaints from that, but it seems likely
that some compilers would not like it.
Back-patch to 9.6 where this code came in, just in case I've underestimated
the possible consequences.
Discussion: https://postgr.es/m/18437.1515607610@sss.pgh.pa.us
As src/backend/access/transam/README says, PageGetLSN may only be called
by processes holding either exclusive lock on buffer, or a shared lock
on buffer plus buffer header lock. Therefore any place that only holds
a shared buffer lock must use BufferGetLSNAtomic instead of PageGetLSN,
which internally obtains buffer header lock prior to reading the LSN.
A few callsites failed to comply with this rule. This was detected by
running all tests under a new (not committed) assertion that verifies
PageGetLSN locking contract. All but one of the callsites that failed
the assertion are fixed by this patch. Remaining callsites were
inspected manually and determined not to need any change.
The exception (unfixed callsite) is in TestForOldSnapshot, which only
has a Page argument, making it impossible to access the corresponding
Buffer from it. Fixing that seems a much larger patch that will have to
be done separately; and that's just as well, since it was only
introduced in 9.6 and other bugs are much older.
Some of these bugs are ancient; backpatch all the way back to 9.3.
Authors: Jacob Champion, Asim Praveen, Ashwin Agrawal
Reviewed-by: Michaël Paquier
Discussion: https://postgr.es/m/CABAq_6GXgQDVu3u12mK9O5Xt5abBZWQ0V40LZCE+oUf95XyNFg@mail.gmail.com
Logical decoding's reorderbuffer.c may spill transaction files to disk
when transactions are large. These are supposed to be removed when they
become "too old" by xid; but file removal requires the boundary LSNs of
the transaction to be known. The final_lsn is only set when we see the
commit or abort record for the transaction, but nothing sets the value
for transactions that crash, so the removal code misbehaves -- in
assertion-enabled builds, it crashes by a failed assertion.
To fix, modify the final_lsn of transactions that don't have a value
set, to the LSN of the very latest change in the transaction. This
causes the spilled files to be removed appropriately.
Author: Atsushi Torikoshi
Reviewed-by: Kyotaro HORIGUCHI, Craig Ringer, Masahiko Sawada
Discussion: https://postgr.es/m/54e4e488-186b-a056-6628-50628e4e4ebc@lab.ntt.co.jp
Instead of using our standard macro for this calculation, this code
did it itself ... and got it wrong, leading to incorrect display of
the null bitmap in some cases. Noted and fixed by Maksim Milyutin.
In passing, remove a uselessly duplicative error check.
Errors were introduced in commit d6061f83a; back-patch to 9.6
where that came in.
Maksim Milyutin, reviewed by Andrey Borodin
Discussion: https://postgr.es/m/ec295792-a69f-350f-6287-25a20e8f31d5@gmail.com
This reverts commit 2268e6afd596. It turned out that inconsistency in
the report is still possible, so go back to the simpler formulation of
the test and instead add an alternate expected output.
Discussion: https://postgr.es/m/20180103193728.ysqpcp2xjnqpiep7@alvherre.pgsql
Upcoming versions of glibc will contain copy_file_range(2), a wrapper
around a new linux syscall for in-kernel copying of data ranges. This
conflicts with pg_rewinds function of the same name.
Therefore rename pg_rewinds version. As our version isn't a generic
copying facility we decided to choose a rewind specific function name.
Per buildfarm animal caiman and subsequent discussion with Tom Lane.
Author: Andres Freund
Discussion:
https://postgr.es/m/20180103033425.w7jkljth3e26sduc@alap3.anarazel.dehttps://postgr.es/m/31122.1514951044@sss.pgh.pa.us
Backpatch: 9.5-, where pg_rewind was introduced
