Fix bug in determining when recovery has reached consistency.

When starting WAL replay from an online checkpoint, the last replayed WAL
record variable was initialized using the checkpoint record's location, even
though the records between the REDO location and the checkpoint record had
not been replayed yet. That was noted as "slightly confusing" but harmless
in the comment, but in some cases, it fooled CheckRecoveryConsistency to
incorrectly conclude that we had already reached a consistent state
immediately at the beginning of WAL replay. That caused the system to accept
read-only connections in hot standby mode too early, and also PANICs with
message "WAL contains references to invalid pages".

Fix by initializing the variables to the REDO location instead.

In 9.2 and above, change CheckRecoveryConsistency() to use
lastReplayedEndRecPtr variable when checking if backup end location has
been reached. It was inconsistently using EndRecPtr for that check, but
lastReplayedEndRecPtr when checking min recovery point. It made no
difference before this patch, because in all the places where
CheckRecoveryConsistency was called the two variables were the same, but
it was always an accident waiting to happen, and would have been wrong
after this patch anyway.

Report and analysis by Tomonari Katsumata, bug #8686. Backpatch to 9.0,
where hot standby was introduced.
Fix pause_at_recovery_target + recovery_target_inclusive combination.

If pause_at_recovery_target is set, recovery pauses *before* applying the
target record, even if recovery_target_inclusive is set. If you then
continue with pg_xlog_replay_resume(), it will apply the target record
before ending recovery. In other words, if you log in while it's paused
and verify that the database looks OK, ending recovery changes its state
again, possibly destroying data that you were tring to salvage with PITR.

Backpatch to 9.1, this has been broken since pause_at_recovery_target was
added.
Fix "cannot accept a set" error when only some arms of a CASE return a set.

In commit c1352052ef1d4eeb2eb1d822a207ddc2d106cb13, I implemented an
optimization that assumed that a function's argument expressions would
either always return a set (ie multiple rows), or always not.  This is
wrong however: we allow CASE expressions in which some arms return a set
of some type and others just return a scalar of that type.  There may be
other examples as well.  To fix, replace the run-time test of whether an
argument returned a set with a static precheck (expression_returns_set).
This adds a little bit of query startup overhead, but it seems barely
measurable.

Per bug #8228 from David Johnston.  This has been broken since 8.0,
so patch all supported branches.
Fix descriptor output in ECPG.

While working on most platforms the old way sometimes created alignment
problems. This should fix it. Also the regresion tests were updated to test for
the reported case.

Report and fix by MauMau <maumau307@gmail.com>
Accept pg_upgraded tuples during multixact freezing

The new MultiXact freezing routines introduced by commit 8e9a16ab8f7
neglected to consider tuples that came from a pg_upgrade'd database; a
vacuum run that tried to freeze such tuples would die with an error such
as
ERROR: MultiXactId 11415437 does no longer exist -- apparent wraparound

To fix, ensure that GetMultiXactIdMembers is allowed to return empty
multis when the infomask bits are right, as is done in other callsites.

Per trouble report from F-Secure.

In passing, fix a copy&paste bug reported by Andrey Karpov from VIVA64
from their PVS-Studio static checked, that instead of setting relminmxid
to Invalid, we were setting relfrozenxid twice.  Not an important
mistake because that code branch is about relations for which we don't
use the frozenxid/minmxid values at all in the first place, but seems to
warrants a fix nonetheless.
Fix compute_scalar_stats() for case that all values exceed WIDTH_THRESHOLD.

The standard typanalyze functions skip over values whose detoasted size
exceeds WIDTH_THRESHOLD (1024 bytes), so as to limit memory bloat during
ANALYZE.  However, we (I think I, actually :-() failed to consider the
possibility that *every* non-null value in a column is too wide.  While
compute_minimal_stats() seems to behave reasonably anyway in such a case,
compute_scalar_stats() just fell through and generated no pg_statistic
entry at all.  That's unnecessarily pessimistic: we can still produce
valid stanullfrac and stawidth values in such cases, since we do include
too-wide values in the average-width calculation.  Furthermore, since the
general assumption in this code is that too-wide values are probably all
distinct from each other, it seems reasonable to set stadistinct to -1
("all distinct").

Per complaint from Kadri Raudsepp.  This has been like this since roughly
neolithic times, so back-patch to all supported branches.
Fix possible crashes due to using elog/ereport too early in startup.

Per reports from Andres Freund and Luke Campbell, a server failure during
set_pglocale_pgservice results in a segfault rather than a useful error
message, because the infrastructure needed to use ereport hasn't been
initialized; specifically, MemoryContextInit hasn't been called.
One known cause of this is starting the server in a directory it
doesn't have permission to read.

We could try to prevent set_pglocale_pgservice from using anything that
depends on palloc or elog, but that would be messy, and the odds of future
breakage seem high.  Moreover there are other things being called in main.c
that look likely to use palloc or elog too --- perhaps those things
shouldn't be there, but they are there today.  The best solution seems to
be to move the call of MemoryContextInit to very early in the backend's
real main() function.  I've verified that an elog or ereport occurring
immediately after that is now capable of sending something useful to
stderr.

I also added code to elog.c to print something intelligible rather than
just crashing if MemoryContextInit hasn't created the ErrorContext.
This could happen if MemoryContextInit itself fails (due to malloc
failure), and provides some future-proofing against someone trying to
sneak in new code even earlier in server startup.

Back-patch to all supported branches.  Since we've only heard reports of
this type of failure recently, it may be that some recent change has made
it more likely to see a crash of this kind; but it sure looks like it's
broken all the way back.
Disallow LATERAL references to the target table of an UPDATE/DELETE.

On second thought, commit 0c051c90082da0b7e5bcaf9aabcbd4f361137cdc was
over-hasty: rather than allowing this case, we ought to reject it for now.
That leaves the field clear for a future feature that allows the target
table to be re-specified in the FROM (or USING) clause, which will enable
left-joining the target table to something else.  We can then also allow
LATERAL references to such an explicitly re-specified target table.
But allowing them right now will create ambiguities or worse for such a
feature, and it isn't something we documented 9.3 as supporting.

While at it, add a convenience subroutine to avoid having several copies
of the ereport for disalllowed-LATERAL-reference cases.
Fix pg_dumpall on pre-8.1 servers

rolname did not exist in pg_shadow.

Backpatch to 9.3

Report by Andrew Gierth via IRC
Add OVERLAPS to index in the docs.

Per report from Adam Mackler and Jonathan Katz
Fix calculation of ISMN check digit.

This has always been broken, so back-patch to all supported versions.

Fabien COELHO
Fix possible buffer overrun in contrib/pg_trgm.

Allow for the possibility that folding a string to lower case makes it
longer (due to replacing a character with a longer multibyte character).
This doesn't change the number of trigrams that will be extracted, but
it does affect the required size of an intermediate buffer in
generate_trgm().  Per bug #8821 from Ufuk Kayserilioglu.

Also install some checks that the input string length is not so large
as to cause overflow in the calculations of palloc request sizes.

Back-patch to all supported versions.
Fix multiple bugs in index page locking during hot-standby WAL replay.

In ordinary operation, VACUUM must be careful to take a cleanup lock on
each leaf page of a btree index; this ensures that no indexscans could
still be "in flight" to heap tuples due to be deleted.  (Because of
possible index-tuple motion due to concurrent page splits, it's not enough
to lock only the pages we're deleting index tuples from.)  In Hot Standby,
the WAL replay process must likewise lock every leaf page.  There were
several bugs in the code for that:

* The replay scan might come across unused, all-zero pages in the index.
While btree_xlog_vacuum itself did the right thing (ie, nothing) with
such pages, xlogutils.c supposed that such pages must be corrupt and
would throw an error.  This accounts for various reports of replication
failures with "PANIC: WAL contains references to invalid pages".  To
fix, add a ReadBufferMode value that instructs XLogReadBufferExtended
not to complain when we're doing this.

* btree_xlog_vacuum performed the extra locking if standbyState ==
STANDBY_SNAPSHOT_READY, but that's not the correct test: we won't open up
for hot standby queries until the database has reached consistency, and
we don't want to do the extra locking till then either, for fear of reading
corrupted pages (which bufmgr.c would complain about).  Fix by exporting a
new function from xlog.c that will report whether we're actually in hot
standby replay mode.

* To ensure full coverage of the index in the replay scan, btvacuumscan
would emit a dummy WAL record for the last page of the index, if no
vacuuming work had been done on that page.  However, if the last page
of the index is all-zero, that would result in corruption of said page,
since the functions called on it weren't prepared to handle that case.
There's no need to lock any such pages, so change the logic to target
the last normal leaf page instead.

The first two of these bugs were diagnosed by Andres Freund, the other one
by me.  Fixes based on ideas from Heikki Linnakangas and myself.

This has been wrong since Hot Standby was introduced, so back-patch to 9.0.
Improve FILES section of psql reference page.

Primarily, explain where to find the system-wide psqlrc file, per recent
gripe from John Sutton.  Do some general wordsmithing and improve the
markup, too.

Also adjust psqlrc.sample so its comments about file location are somewhat
trustworthy.  (Not sure why we bother with this file when it's empty,
but whatever.)

Back-patch to 9.2 where the startup file naming scheme was last changed.
Merge remote-tracking branch 'origin/REL9_3_STABLE' into mga93