If a plan node output expression returns an "expanded" datum, and that
output column is referenced in more than one place in upper-level plan
nodes, we need to ensure that what is returned is a read-only reference
not a read/write reference. Otherwise one of the referencing sites could
scribble on or even delete the expanded datum before we have evaluated the
others. Commit 1dc5ebc907, which introduced this feature, supposed
that it'd be sufficient to make SubqueryScan nodes force their output
columns to read-only state. The folly of that was revealed by bug #14174
from Andrew Gierth, and really should have been immediately obvious
considering that the planner will happily optimize SubqueryScan nodes
out of the plan without any regard for this issue.
The safest fix seems to be to make ExecProject() force its results into
read-only state; that will cover every case where a plan node returns
expression results. Actually we can delegate this to ExecTargetList()
since we can recursively assume that plain Vars will not reference
read-write datums. That should keep the extra overhead down to something
minimal. We no longer need ExecMakeSlotContentsReadOnly(), which was
introduced only in support of the idea that just a few plan node types
would need to do this.
In the future it would be nice to have the planner account for this problem
and inject force-to-read-only expression evaluation nodes into only the
places where there's a risk of multiple evaluation. That's not a suitable
solution for 9.5 or even 9.6 at this point, though.
Report: <20160603124628.9932.41279@wrigleys.postgresql.org>
Adopt the same solution as in commit aa90e148ca, but this time
let's put the ugliness inside the write_stderr() macro, instead of
expecting each call site to deal with it. Back-port that decision
into psql/common.c where I got the macro from in the first place.
Per gripe from Peter Eisentraut.
Formerly, Unix builds of pg_dump/pg_restore would trap SIGINT and similar
signals and set a flag that was tested in various data-transfer loops.
This was prone to errors of omission (cf commit 3c8aa6654); and even if
the client-side response was prompt, we did nothing that would cause
long-running SQL commands (e.g. CREATE INDEX) to terminate early.
Also, the master process would effectively do nothing at all upon receipt
of SIGINT; the only reason it seemed to work was that in typical scenarios
the signal would also be delivered to the child processes. We should
support termination when a signal is delivered only to the master process,
though.
Windows builds had no console interrupt handler, so they would just fall
over immediately at control-C, again leaving long-running SQL commands to
finish unmolested.
To fix, remove the flag-checking approach altogether. Instead, allow the
Unix signal handler to send a cancel request directly and then exit(1).
In the master process, also have it forward the signal to the children.
On Windows, add a console interrupt handler that behaves approximately
the same. The main difference is that a single execution of the Windows
handler can send all the cancel requests since all the info is available
in one process, whereas on Unix each process sends a cancel only for its
own database connection.
In passing, fix an old problem that DisconnectDatabase tends to send a
cancel request before exiting a parallel worker, even if nothing went
wrong. This is at least a waste of cycles, and could lead to unexpected
log messages, or maybe even data loss if it happened in pg_restore (though
in the current code the problem seems to affect only pg_dump). The cause
was that after a COPY step, pg_dump was leaving libpq in PGASYNC_BUSY
state, causing PQtransactionStatus() to report PQTRANS_ACTIVE. That's
normally harmless because the next PQexec() will silently clear the
PGASYNC_BUSY state; but in a parallel worker we might exit without any
additional SQL commands after a COPY step. So add an extra PQgetResult()
call after a COPY to allow libpq to return to PGASYNC_IDLE state.
This is a bug fix, IMO, so back-patch to 9.3 where parallel dump/restore
were introduced.
Thanks to Kyotaro Horiguchi for Windows testing and code suggestions.
Original-Patch: <7005.1464657274@sss.pgh.pa.us>
Discussion: <20160602.174941.256342236.horiguchi.kyotaro@lab.ntt.co.jp>
Commit 2ed5b87f96 introduced a bug in
mark/restore, in an attempt to optimize repeated restores to the
same page. This caused an assertion failure during a merge join
which fed directly from an index scan, although the impact would
not be limited to that case. Revert the bad chunk of code from
that commit.
While investigating this bug it was discovered that a particular
"paranoia" set of the mark position field would not prevent bad
behavior; it would just make it harder to diagnose. Change that
into an assertion, which will draw attention to any future problem
in that area more directly.
Backpatch to 9.5, where the bug was introduced.
Bug #14169 reported by Shinta Koyanagi.
Preliminary analysis by Tom Lane identified which commit caused
the bug.
Parallel dump did a totally pointless query to find out the name of each
table to be dumped, which it already knows. Parallel restore runs issued
lots of redundant SET commands because _doSetFixedOutputState() was invoked
once per TOC item rather than just once at connection start. While the
extra queries are insignificant if you're dumping or restoring large
tables, it still seems worth getting rid of them.
Also, give the responsibility for selecting the right client_encoding for
a parallel dump worker to setup_connection() where it naturally belongs,
instead of having ad-hoc code for that in CloneArchive(). And fix some
minor bugs like use of strdup() where pg_strdup() would be safer.
Back-patch to 9.3, mostly to keep the branches in sync in an area that
we're still finding bugs in.
Discussion: <5086.1464793073@sss.pgh.pa.us>
The original intent in the stats collector was that we should not write out
stats data oftener than every PGSTAT_STAT_INTERVAL msec. Backends will not
make requests at all if they see the existing data is newer than that, and
the stats collector is supposed to disregard requests having a cutoff_time
older than its most recently written data, so that close-together requests
don't result in multiple writes. But the latter part of that got broken
in commit 187492b6c2, so that if two backends concurrently decide
the existing stats are too old, the collector would write the data twice.
(In principle the collector's logic would still merge requests as long as
the second one arrives before we've actually written data ... but since
the message collection loop would write data immediately after processing
a single inquiry message, that never happened in practice, and in any case
the window in which it might work would be much shorter than
PGSTAT_STAT_INTERVAL.)
To fix, improve pgstat_recv_inquiry so that it checks whether the cutoff
time is too old, and doesn't add a request to the queue if so. This means
that we do not need DBWriteRequest.request_time, because the decision is
taken before making a queue entry. And that means that we don't really
need the DBWriteRequest data structure at all; an OID list of database
OIDs will serve and allow removal of some rather verbose and crufty code.
In passing, improve the comments in this area, which have been rather
neglected. Also change backend_read_statsfile so that it's not silently
relying on MyDatabaseId to have some particular value in the autovacuum
launcher process. It accidentally worked as desired because MyDatabaseId
is zero in that process; but that does not seem like a dependency we want,
especially with no documentation about it.
Although this patch is mine, it turns out I'd rediscovered a known bug,
for which Tomas Vondra had already submitted a patch that's functionally
equivalent to the non-cosmetic aspects of this patch. Thanks to Tomas
for reviewing this version.
Back-patch to 9.3 where the bug was introduced.
Prior-Discussion: <1718942738eb65c8407fcd864883f4c8@fuzzy.cz>
Patch: <4625.1464202586@sss.pgh.pa.us>
BRIN was relying on the ability to remove a tuple from an index page,
then putting another tuple in the same line pointer. But PageAddItem
refuses to add a tuple beyond the first free item past the last used
item, and in particular, it rejects an attempt to add an item to an
empty page anywhere other than the first line pointer. PageAddItem
issues a WARNING and indicates to the caller that it failed, which in
turn causes the BRIN calling code to issue a PANIC, so the whole
sequence looks like this:
WARNING: specified item offset is too large
PANIC: failed to add BRIN tuple
To fix, create a new function PageAddItemExtended which is like
PageAddItem except that the two boolean arguments become a flags bitmap;
the "overwrite" and "is_heap" boolean flags in PageAddItem become
PAI_OVERWITE and PAI_IS_HEAP flags in the new function, and a new flag
PAI_ALLOW_FAR_OFFSET enables the behavior required by BRIN.
PageAddItem() retains its original signature, for compatibility with
third-party modules (other callers in core code are not modified,
either).
Also, in the belt-and-suspenders spirit, I added a new sanity check in
brinGetTupleForHeapBlock to raise an error if an TID found in the revmap
is not marked as live by the page header. This causes it to react with
"ERROR: corrupted BRIN index" to the bug at hand, rather than a hard
crash.
Backpatch to 9.5.
Bug reported by Andreas Seltenreich as detected by his handy sqlsmith
fuzzer.
Discussion: https://www.postgresql.org/message-id/87mvni77jh.fsf@elite.ansel.ydns.eu
Parallel restore from directory format failed to respond to control-C
in a timely manner, because there were no checkAborting() calls in the
code path that reads data from a file and sends it to the backend.
If any worker was in the midst of restoring data for a large table,
you'd just have to wait.
This fix doesn't do anything for the problem of aborting a long-running
server-side command, but at least it fixes things for data transfers.
Back-patch to 9.3 where parallel restore was introduced.
This was effectively dead code, since the places that tested it could not
be reached after we entered the on-exit-cleanup routine that would set it.
It seems to have been a leftover from a design in which error abort would
try to send fresh commands to the workers --- a design which could never
have worked reliably, of course. Since the flag is not cross-platform, it
complicates reasoning about the code's behavior, which we could do without.
Although this is effectively just cosmetic, back-patch anyway, because
there are some actual bugs in the vicinity of this behavior.
Discussion: <15583.1464462418@sss.pgh.pa.us>
The commentary in this file was in extremely sad shape. The author(s)
had clearly never heard of the project convention that a function header
comment should provide an API spec of some sort for that function. Much
of it was flat out wrong, too --- maybe it was accurate when written, but
if so it had not been updated to track subsequent code revisions. Rewrite
and rearrange to try to bring it up to speed, and annotate some of the
places where more work is needed. (I've refrained from actually fixing
anything of substance ... yet.)
Also, rename a couple of functions for more clarity as to what they do,
do some very minor code rearrangement, remove some pointless Asserts,
fix an incorrect Assert in readMessageFromPipe, and add a missing socket
close in one error exit from pgpipe(). The last would be a bug if we
tried to continue after pgpipe() failure, but since we don't, it's just
cosmetic at present.
Although this is only cosmetic, back-patch to 9.3 where parallel.c was
added. It's sufficiently invasive that it'll pose a hazard for future
back-patching if we don't.
Discussion: <25239.1464386067@sss.pgh.pa.us>
Since we start the worker threads with _beginthreadex(), we should use
_endthreadex() to terminate them. We got this right in the normal-exit
code path, but not so much during an error exit from a worker.
In addition, be sure to apply CloseHandle to the thread handle after
each thread exits.
It's not clear that these oversights cause any user-visible problems,
since the pg_dump run is about to terminate anyway. Still, it's clearly
better to follow Microsoft's API specifications than ignore them.
Also a few cosmetic cleanups in WaitForTerminatingWorkers(), including
being a bit less random about where to cast between uintptr_t and HANDLE,
and being sure to clear the worker identity field for each dead worker
(not that false matches should be possible later, but let's be careful).
Original observation and patch by Armin Schöffmann, cosmetic improvements
by Michael Paquier and me. (Armin's patch also included closing sockets
in ShutdownWorkersHard(), but that's been dealt with already in commit
df8d2d8c4.) Back-patch to 9.3 where parallel pg_dump was introduced.
Discussion: <zarafa.570306bd.3418.074bf1420d8f2ba2@root.aegaeon.de>
If both timeout indicators are set when we arrive at ProcessInterrupts,
we've historically just reported "lock timeout". However, some buildfarm
members have been observed to fail isolationtester's timeouts test by
reporting "lock timeout" when the statement timeout was expected to fire
first. The cause seems to be that the process is allowed to sleep longer
than expected (probably due to heavy machine load) so that the lock
timeout happens before we reach the point of reporting the error, and
then this arbitrary tiebreak rule does the wrong thing. We can improve
matters by comparing the scheduled timeout times to decide which error
to report.
I had originally proposed greatly reducing the 1-second window between
the two timeouts in the test cases. On reflection that is a bad idea,
at least for the case where the lock timeout is expected to fire first,
because that would assume that it takes negligible time to get from
statement start to the beginning of the lock wait. Thus, this patch
doesn't completely remove the risk of test failures on slow machines.
Empirically, however, the case this handles is the one we are seeing
in the buildfarm. The explanation may be that the other case requires
the scheduler to take the CPU away from a busy process, whereas the
case fixed here only requires the scheduler to not give the CPU back
right away to a process that has been woken from a multi-second sleep
(and, perhaps, has been swapped out meanwhile).
Back-patch to 9.3 where the isolationtester timeouts test was added.
Discussion: <8693.1464314819@sss.pgh.pa.us>
Getting a synchronized snapshot is not supported on a hot standby node,
and is by default taken when using -j with multiple sessions. Trying to
do so still failed, but with a server error that would also go in the
log. Instead, proprely detect this case and give a better error message.
For some reason the code to emit a warning and switch to uncompressed
output was placed down in the guts of pg_backup_archiver.c. This is
definitely too late in the case of parallel operation (and I rather
wonder if it wasn't too late for other purposes as well). Put it in
pg_dump.c's option-processing logic, which seems a much saner place.
Also, the default behavior with custom or directory output format was
to emit the warning telling you the output would be uncompressed. This
seems unhelpful, so silence that case.
Back-patch to 9.3 where parallel dump was introduced.
Kyotaro Horiguchi, adjusted a bit by me
Report: <20160526.185551.242041780.horiguchi.kyotaro@lab.ntt.co.jp>
The Windows coding of ShutdownWorkersHard() thought that setting termEvent
was sufficient to make workers exit after an error. But that only helps
if a worker is busy and passes through checkAborting(). An idle worker
will just sit, resulting in pg_dump failing to exit until the user gives up
and hits control-C. We should close the write end of the command pipe
so that idle workers will see socket EOF and exit, as the Unix coding was
already doing.
Back-patch to 9.3 where parallel pg_dump was introduced.
Kyotaro Horiguchi
Ever since we split the statistics collector's reports into per-database
files (commit 187492b6c2), backends have been seeing stale statistics
for shared catalogs. This is because the inquiry message only prompts the
collector to write the per-database file for the requesting backend's own
database. Stats for shared catalogs are in a separate file for "DB 0",
which didn't get updated.
In normal operation this was partially masked by the fact that the
autovacuum launcher would send an inquiry message at least once per
autovacuum_naptime that asked for "DB 0"; so the shared-catalog stats would
never be more than a minute out of date. However the problem becomes very
obvious with autovacuum disabled, as reported by Peter Eisentraut.
To fix, redefine the semantics of inquiry messages so that both the
specified DB and DB 0 will be dumped. (This might seem a bit inefficient,
but we have no good way to know whether a backend's transaction will look
at shared-catalog stats, so we have to read both groups of stats whenever
we request stats. Sending two inquiry messages would definitely not be
better.)
Back-patch to 9.3 where the bug was introduced.
Report: <56AD41AC.1030509@gmx.net>
In the original design for parallel dump, worker processes reported errors
by sending them up to the master process, which would print the messages.
This is unworkably fragile for a couple of reasons: it risks deadlock if a
worker sends an error at an unexpected time, and if the master has already
died for some reason, the user will never get to see the error at all.
Revert that idea and go back to just always printing messages to stderr.
This approach means that if all the workers fail for similar reasons (eg,
bad password or server shutdown), the user will see N copies of that
message, not only one as before. While that's slightly annoying, it's
certainly better than not seeing any message; not to mention that we
shouldn't assume that only the first failure is interesting.
An additional problem in the same area was that the master failed to
disable SIGPIPE (at least until much too late), which meant that sending a
command to an already-dead worker would cause the master to crash silently.
That was bad enough in itself but was made worse by the total reliance on
the master to print errors: even if the worker had reported an error, you
would probably not see it, depending on timing. Instead disable SIGPIPE
right after we've forked the workers, before attempting to send them
anything.
Additionally, the master relies on seeing socket EOF to realize that a
worker has exited prematurely --- but on Windows, there would be no EOF
since the socket is attached to the process that includes both the master
and worker threads, so it remains open. Make archive_close_connection()
close the worker end of the sockets so that this acts more like the Unix
case. It's not perfect, because if a worker thread exits without going
through exit_nicely() the closures won't happen; but that's not really
supposed to happen.
This has been wrong all along, so back-patch to 9.3 where parallel dump
was introduced.
Report: <2458.1450894615@sss.pgh.pa.us>
Because vac_update_datfrozenxid() updates datfrozenxid and datminmxid
in-place, it's unsafe to assume that successive reads of those values will
give consistent results. Fetch each one just once to ensure sane behavior
in the minimum calculation. Noted while reviewing Alexander Korotkov's
patch in the same area.
Discussion: <8564.1464116473@sss.pgh.pa.us>
vac_truncate_clog() uses its own transaction ID as the comparison point in
a sanity check that no database's datfrozenxid has already wrapped around
"into the future". That was probably fine when written, but in a lazy
vacuum we won't have assigned an XID, so calling GetCurrentTransactionId()
causes an XID to be assigned when otherwise one would not be. Most of the
time that's not a big problem ... but if we are hard up against the
wraparound limit, consuming XIDs during antiwraparound vacuums is a very
bad thing.
Instead, use ReadNewTransactionId(), which not only avoids this problem
but is in itself a better comparison point to test whether wraparound
has already occurred.
Report and patch by Alexander Korotkov. Back-patch to all versions.
Report: <CAPpHfdspOkmiQsxh-UZw2chM6dRMwXAJGEmmbmqYR=yvM7-s6A@mail.gmail.com>
Needed for cases in which INSERT ... ON CONFLICT appears inside a
recursive CTE item. Per bug #14153 from Thomas Alton.
Patch by Peter Geoghegan, slightly adjusted by me
Report: <20160521232802.22598.13537@wrigleys.postgresql.org>
do_text_output_multiline() would fail (typically with a null pointer
dereference crash) if its input string did not end with a newline. Such
cases do not arise in our current sources; but it certainly could happen
in future, or in extension code's usage of the function, so we should fix
it. To fix, replace "eol += len" with "eol = text + len".
While at it, make two cosmetic improvements: mark the input string const,
and rename the argument from "text" to "txt" to dodge pgindent strangeness
(since "text" is a typedef name).
Even though this problem is only latent at present, it seems like a good
idea to back-patch the fix, since it's a very simple/safe patch and it's
not out of the realm of possibility that we might in future back-patch
something that expects sane behavior from do_text_output_multiline().
Per report from Hao Lee.
Report: <CAGoxFiFPAGyPAJLcFxTB5cGhTW2yOVBDYeqDugYwV4dEd1L_Ag@mail.gmail.com>
Buildfarm member skink failed with symptoms suggesting that an
auto-analyze had happened and changed the plan displayed for a
test query. Although this is evidently of low probability,
regression tests that sometimes fail are no fun, so add commands
to force a bitmap scan to be chosen.
Some comments mentioned XLogReplayBuffer, but there's no such function:
that was an interim name for a function that got renamed to
XLogReadBufferForRedo, before commit 2c03216d83 was pushed.
While it could be argued that rejecting system column mentions in the
ON CONFLICT list is an unsupported feature, falling over altogether
just because the table has a unique index on OID is indubitably a bug.
As far as I can tell, fixing infer_arbiter_indexes() is sufficient to
make ON CONFLICT (oid) actually work, though making a regression test
for that case is problematic because of the impossibility of setting
the OID counter to a known value.
Minor cosmetic cleanups along with the bug fix.
subquery_planner() failed to apply expression preprocessing to the
arbiterElems and arbiterWhere fields of an OnConflictExpr. No doubt the
theory was that this wasn't necessary because we don't actually try to
execute those expressions; but that's wrong, because it results in failure
to match to index expressions or index predicates that are changed at all
by preprocessing. Per bug #14132 from Reynold Smith.
Also add pullup_replace_vars processing for onConflictWhere. Perhaps
it's impossible to have a subquery reference there, but I'm not exactly
convinced; and even if true today it's a failure waiting to happen.
Also add some comments to other places where one or another field of
OnConflictExpr is intentionally ignored, with explanation as to why it's
okay to do so.
Also, catalog/dependency.c failed to record any dependency on the named
constraint in ON CONFLICT ON CONSTRAINT, allowing such a constraint to
be dropped while rules exist that depend on it, and allowing pg_dump to
dump such a rule before the constraint it refers to. The normal execution
path managed to error out reasonably for a dangling constraint reference,
but ruleutils.c dumped core; so in addition to fixing the omission, add
a protective check in ruleutils.c, since we can't retroactively add a
dependency in existing databases.
Back-patch to 9.5 where this code was introduced.
Report: <20160510190350.2608.48667@wrigleys.postgresql.org>
The table-skipping logic in autovacuum would fail to consider that
multiple workers could be processing the same shared catalog in
different databases. This normally wouldn't be a problem: firstly
because autovacuum workers not for wraparound would simply ignore tables
in which they cannot acquire lock, and secondly because most of the time
these tables are small enough that even if multiple for-wraparound
workers are stuck in the same catalog, they would be over pretty
quickly. But in cases where the catalogs are severely bloated it could
become a problem.
Backpatch all the way back, because the problem has been there since the
beginning.
Reported by Ondřej Světlík
Discussion: https://www.postgresql.org/message-id/572B63B1.3030603%40flexibee.euhttps://www.postgresql.org/message-id/572A1072.5080308%40flexibee.eu
In the documentation for nextval(), point out explicitly that INSERT ...
ON CONFLICT will call nextval() if needed for the insertion case, whether
or not it ends up following the ON CONFLICT path. This seems to be a
matter of some confusion, cf bug #14126, so let's be clear about it.
Also mention the issue in the CREATE SEQUENCE reference page, since that
is another place where people might expect such things to be covered.
Minor wording improvements nearby, as well.
Back-patch to 9.5 where ON CONFLICT was introduced.
OpenSSL has an unfortunate tendency to mix per-session state error
handling with per-thread error handling. This can cause problems when
programs that link to libpq with OpenSSL enabled have some other use of
OpenSSL; without care, one caller of OpenSSL may cause problems for the
other caller. Backend code might similarly be affected, for example
when a third party extension independently uses OpenSSL without taking
the appropriate precautions.
To fix, don't trust other users of OpenSSL to clear the per-thread error
queue. Instead, clear the entire per-thread queue ahead of certain I/O
operations when it appears that there might be trouble (these I/O
operations mostly need to call SSL_get_error() to check for success,
which relies on the queue being empty). This is slightly aggressive,
but it's pretty clear that the other callers have a very dubious claim
to ownership of the per-thread queue. Do this is both frontend and
backend code.
Finally, be more careful about clearing our own error queue, so as to
not cause these problems ourself. It's possibly that control previously
did not always reach SSLerrmessage(), where ERR_get_error() was supposed
to be called to clear the queue's earliest code. Make sure
ERR_get_error() is always called, so as to spare other users of OpenSSL
the possibility of similar problems caused by libpq (as opposed to
problems caused by a third party OpenSSL library like PHP's OpenSSL
extension). Again, do this is both frontend and backend code.
See bug #12799 and https://bugs.php.net/bug.php?id=68276
Based on patches by Dave Vitek and Peter Eisentraut.
From: Peter Geoghegan <pg@bowt.ie>
This patch essentially reverts commit 4c6780fd17, in favor of a much
simpler solution for the case where the new cluster would choose to create
a TOAST table but the old cluster doesn't have one: just don't create a
TOAST table.
The existing code failed in at least two different ways if the situation
arose: (1) ALTER TABLE RESET didn't grab an exclusive lock, so that the
lock sanity check in create_toast_table failed; (2) pg_upgrade did not
provide a pg_type OID for the new toast table, so that the crosscheck in
TypeCreate failed. While both these problems were introduced by later
patches, they show that the hack being used to cause TOAST table creation
is overwhelmingly fragile (and untested). I also note that before the
TypeCreate crosscheck was added, the code would have resulted in assigning
an indeterminate pg_type OID to the toast table, possibly causing a later
OID conflict in that catalog; so that it didn't really work even when
committed.
If we simply don't create a TOAST table, there will only be a problem if
the code tries to store a tuple that's wider than a page, and field
compression isn't sufficient to get it under a page. Given that the TOAST
creation threshold is intended to be about a quarter of a page, it's very
hard to believe that cross-version differences in the do-we-need-a-toast-
table heuristic could result in an observable problem. So let's just
follow the old version's conclusion about whether a TOAST table is needed.
(If we ever do change needs_toast_table() so much that this conclusion
doesn't apply, we can devise a solution at that time, and hopefully do
it in a less klugy way than 4c6780fd17 did.)
Back-patch to 9.3, like the previous patch.
Discussion: <8110.1462291671@sss.pgh.pa.us>
to_timestamp() handles the TH/th format codes by advancing over two input
characters, whatever those are. It failed to notice whether there were
two characters available to be skipped, making it possible to advance
the pointer past the end of the input string and keep on parsing.
A similar risk existed in the handling of "Y,YYY" format: it would advance
over three characters after the "," whether or not three characters were
available.
In principle this might be exploitable to disclose contents of server
memory. But the security team concluded that it would be very hard to use
that way, because the parsing loop would stop upon hitting any zero byte,
and TH/th format codes can't be consecutive --- they have to follow some
other format code, which would have to match whatever data is there.
So it seems impractical to examine memory very much beyond the end of the
input string via this bug; and the input string will always be in local
memory not in disk buffers, making it unlikely that anything very
interesting is close to it in a predictable way. So this doesn't quite
rise to the level of needing a CVE.
Thanks to Wolf Roediger for reporting this bug.
DST law changes in Russia (Magadan, Tomsk regions) and Venezuela.
Historical corrections for Russia. There are new zone names Europe/Kirov
and Asia/Tomsk reflecting the fact that these regions now have different
time zone histories from adjacent regions.
Somebody added pg_replication_origin, pg_replication_origin_status and
pg_replication_slots to catalogs.sgml without a whole lot of concern for
either alphabetical order or the difference between a table and a view.
Clean up the mess.
Back-patch to 9.5, not so much because this is critical as because if
I don't it will result in a cross-branch divergence in release-9.5.sgml,
which would be a maintenance hazard.
awk's equality-comparison operator is "==" not "=". We got this right
in many places, but not in configure's checks for supported version
numbers of flex and perl. It hadn't been noticed because unsupported
versions are so old as to be basically extinct in the wild, and because
the only consequence is whether or not a WARNING flies by during
configure.
Daniel Gustafsson noted the problem with respect to the test for flex,
I found the other by reviewing other awk calls.
CHECK_PAGE_OFFSET_RANGE() has been unused forever.
CHECK_RELATION_BLOCK_RANGE() has been unused in pgstatindex.c ever since
bt_page_stats() and bt_page_items() functions were moved from pgstattuple
to pageinspect module. It still exists in pageinspect/btreefuncs.c.
Daniel Gustafsson
Given a three-or-more-way equivalence class, such as X.Y = Y.Y = Z.Z,
it was possible for the planner to omit one of the quals needed to
enforce that all members of the equivalence class are actually equal.
This only happened in the case of a parameterized join node for two
of the relations, that is a plan tree like
Nested Loop
-> Scan X
-> Nested Loop
-> Scan Y
-> Scan Z
Filter: Z.Z = X.X
The eclass machinery normally expects to apply X.X = Y.Y when those
two relations are joined, but in this shape of plan tree they aren't
joined until the top node --- and, if the lower nested loop is marked
as parameterized by X, the top node will assume that the relevant eclass
condition(s) got pushed down into the lower node. On the other hand,
the scan of Z assumes that it's only responsible for constraining Z.Z
to match any one of the other eclass members. So one or another of
the required quals sometimes fell between the cracks, depending on
whether consideration of the eclass in get_joinrel_parampathinfo()
for the lower nested loop chanced to generate X.X = Y.Y or X.X = Z.Z
as the appropriate constraint there. If it generated the latter,
it'd erroneously suppose that the Z scan would take care of matters.
To fix, force X.X = Y.Y to be generated and applied at that join node
when this case occurs.
This is *extremely* hard to hit in practice, because various planner
behaviors conspire to mask the problem; starting with the fact that the
planner doesn't really like to generate a parameterized plan of the
above shape. (It might have been impossible to hit it before we
tweaked things to allow this plan shape for star-schema cases.) Many
thanks to Alexander Kirkouski for submitting a reproducible test case.
The bug can be demonstrated in all branches back to 9.2 where parameterized
paths were introduced, so back-patch that far.
