Fix longstanding race condition in plancache.c.

When creating or manipulating a cached plan for a transaction control
command (particularly ROLLBACK), we must not perform any catalog accesses,
since we might be in an aborted transaction.  However, plancache.c busily
saved or examined the search_path for every cached plan.  If we were
unlucky enough to do this at a moment where the path's expansion into
schema OIDs wasn't already cached, we'd do some catalog accesses; and with
some more bad luck such as an ill-timed signal arrival, that could lead to
crashes or Assert failures, as exhibited in bug #8095 from Nachiket Vaidya.
Fortunately, there's no real need to consider the search path for such
commands, so we can just skip the relevant steps when the subject statement
is a TransactionStmt.  This is somewhat related to bug #5269, though the
failure happens during initial cached-plan creation rather than
revalidation.

This bug has been there since the plan cache was invented, so back-patch
to all supported branches.
doc: Fix syntax in example

LANGUAGE 'plpgsql' no longer works.  The single quotes need to be
removed.

Erwin Brandstetter
Fix typo in comment.

Peter Geoghegan
Avoid deadlock between concurrent CREATE INDEX CONCURRENTLY commands.

There was a high probability of two or more concurrent C.I.C. commands
deadlocking just before completion, because each would wait for the others
to release their reference snapshots.  Fix by releasing the snapshot
before waiting for other snapshots to go away.

Per report from Paul Hinze.  Back-patch to all active branches.
Ensure that user created rows in extension tables get dumped if the table is explicitly requested, either with a -t/--table switch of the table itself, or by -n/--schema switch of the schema containing the extension table. Patch reviewed by Vibhor Kumar and Dimitri Fontaine.

Backpatched to 9.1 when the extension management facility was added.
Ensure ANALYZE phase is not skipped because of canceled truncate.

Patch b19e4250b45e91c9cbdd18d35ea6391ab5961c8d attempted to
preserve existing behavior regarding statistics generation in the
case that a truncation attempt was canceled due to lock conflicts.
It failed to do this accurately in two regards: (1) autovacuum had
previously generated statistics if the truncate attempt failed to
initially get the lock rather than having started the attempt, and
(2) the VACUUM ANALYZE command had always generated statistics.

Both of these changes were unintended, and are reverted by this
patch.  On review, there seems to be consensus that the previous
failure to generate statistics when the truncate was terminated
was more an unfortunate consequence of how that effort was
previously terminated than a feature we want to keep; so this
patch generates statistics even when an autovacuum truncation
attempt terminates early.  Another unintended change which is kept
on the basis that it is an improvement is that when a VACUUM
command is truncating, it will the new heuristic for avoiding
blocking other processes, rather than keeping an
AccessExclusiveLock on the table for however long the truncation
takes.

Per multiple reports, with some renaming per patch by Jeff Janes.

Backpatch to 9.0, where problem was created.
Postpone creation of pathkeys lists to fix bug #8049.

This patch gets rid of the concept of, and infrastructure for,
non-canonical PathKeys; we now only ever create canonical pathkey lists.

The need for non-canonical pathkeys came from the desire to have
grouping_planner initialize query_pathkeys and related pathkey lists before
calling query_planner.  However, since query_planner didn't actually *do*
anything with those lists before they'd been made canonical, we can get rid
of the whole mess by just not creating the lists at all until the point
where we formerly canonicalized them.

There are several ways in which we could implement that without making
query_planner itself deal with grouping/sorting features (which are
supposed to be the province of grouping_planner).  I chose to add a
callback function to query_planner's API; other alternatives would have
required adding more fields to PlannerInfo, which while not bad in itself
would create an ABI break for planner-related plugins in the 9.2 release
series.  This still breaks ABI for anything that calls query_planner
directly, but it seems somewhat unlikely that there are any such plugins.

I had originally conceived of this change as merely a step on the way to
fixing bug #8049 from Teun Hoogendoorn; but it turns out that this fixes
that bug all by itself, as per the added regression test.  The reason is
that now get_eclass_for_sort_expr is adding the ORDER BY expression at the
end of EquivalenceClass creation not the start, and so anything that is in
a multi-member EquivalenceClass has already been created with correct
em_nullable_relids.  I am suspicious that there are related scenarios in
which we still need to teach get_eclass_for_sort_expr to compute correct
nullable_relids, but am not eager to risk destabilizing either 9.2 or 9.3
to fix bugs that are only hypothetical.  So for the moment, do this and
stop here.

Back-patch to 9.2 but not to earlier branches, since they don't exhibit
this bug for lack of join-clause-movement logic that depends on
em_nullable_relids being correct.  (We might have to revisit that choice
if any related bugs turn up.)  In 9.2, don't change the signature of
make_pathkeys_for_sortclauses nor remove canonicalize_pathkeys, so as
not to risk more plugin breakage than we have to.
Install recycled WAL segments with current timeline ID during recovery.

This is a follow-up to the earlier fix, which changed the recycling logic
to recycle WAL segments under the current recovery target timeline. That
turns out to be a bad idea, because installing a recycled segment with
a TLI higher than what we're recovering at the moment means that the recovery
logic will find the recycled WAL segment and try to replay it. It will fail,
but but the mere presence of such a WAL segment will mask any other, real,
file with the same log/seg, but smaller TLI.

Per report from Mitsumasa Kondo. Apply to 9.1 and 9.2, like the previous
fix. Master was already doing this differently; this patch makes 9.1 and
9.2 to do the same thing as master.
Fix permission tests for views/tables proven empty by constraint exclusion.

A view defined as "select <something> where false" had the curious property
that the system wouldn't check whether users had the privileges necessary
to select from it.  More generally, permissions checks could be skipped
for tables referenced in sub-selects or views that were proven empty by
constraint exclusion (although some quick testing suggests this seldom
happens in cases of practical interest).  This happened because the planner
failed to include rangetable entries for such tables in the finished plan.

This was noticed in connection with erroneous handling of materialized
views, but actually the issue is quite unrelated to matviews.  Therefore,
revert commit 200ba1667b3a8d7a9d559d2f05f83d209c9d8267 in favor of a more
direct test for the real problem.

Back-patch to 9.2 where the bug was introduced (by commit
7741dd6590073719688891898e85f0cb73453159).
Fix thinko in comment.

WAL segment means a 16 MB physical WAL file; this comment meant a logical
4 GB log file.

Amit Langote. Apply to backbranches only, as the comment is gone in master.
docs:  fix log_line_prefix session id docs

Backpatch to 9.2.

Report from Ian Lawrence Barwick
docs:  log_line_prefix session id fix

Restore 4-byte designation for docs.  Fix 9.3 doc query to properly pad
to four digits.

Backpatch to all active branches

Per suggestions from Ian Lawrence Barwick
Revert "Fix permission tests for views/tables proven empty by constraint exclusion."

This reverts commit 15b0421002624919c62ae3c6574af2a8452bf6c4.  Per
complaint from Robert Haas, that patch caused crashes on appendrel
cases, and it didn't fix all forms of the problem anyway.  Consensus
is we'll leave this problem alone in the back branches, at least
for now.
Use pg_dump's --quote-all-identifiers option in pg_upgrade.

This helps guard against changes in the set of reserved keywords from
one version to another.  In theory it should only be an issue if we
de-reserve a keyword in a newer release, since that can create the type
of problem shown in bug #8128.

Back-patch to 9.1 where the --quote-all-identifiers option was added.
Fix management of fn_extra caching during repeated GiST index scans.

Commit d22a09dc70f9830fa78c1cd1a3a453e4e473d354 introduced official support
for GiST consistentFns that want to cache data using the FmgrInfo fn_extra
pointer: the idea was to preserve the cached values across gistrescan(),
whereas formerly they'd been leaked.  However, there was an oversight in
that, namely that multiple scan keys might reference the same column's
consistentFn; the code would result in propagating the same cache value
into multiple scan keys, resulting in crashes or wrong answers.  Use a
separate array instead to ensure that each scan key keeps its own state.

Per bug #8143 from Joel Roller.  Back-patch to 9.2 where the bug was
introduced.
Fix pgp_pub_decrypt() so it works for secret keys with passwords.

Per report from Keith Fiske.

Marko Kreen
Guard against input_rows == 0 in estimate_num_groups().

This case doesn't normally happen, because the planner usually clamps
all row estimates to at least one row; but I found that it can arise
when dealing with relations excluded by constraints.  Without a defense,
estimate_num_groups() can return zero, which leads to divisions by zero
inside the planner as well as assertion failures in the executor.

An alternative fix would be to change set_dummy_rel_pathlist() to make
the size estimate for a dummy relation 1 row instead of 0, but that seemed
pretty ugly; and probably someday we'll want to drop the convention that
the minimum rowcount estimate is 1 row.

Back-patch to 8.4, as the problem can be demonstrated that far back.
Update CREATE FUNCTION documentation about argument names.

The 9.2 patch that added argument name support in SQL-language functions
missed updating a parenthetical comment about that in the CREATE FUNCTION
reference page.  Noted by Erwin Brandstetter.
Fix handling of OID wraparound while in standalone mode.

If OID wraparound should occur while in standalone mode (unlikely but
possible), we want to advance the counter to FirstNormalObjectId not
FirstBootstrapObjectId.  Otherwise, user objects might be created with OIDs
in the system-reserved range.  That isn't immediately harmful but it poses
a risk of conflicts during future pg_upgrade operations.

Noted by Andres Freund.  Back-patch to all supported branches, since all of
them are supported sources for pg_upgrade operations.
Fix fd.c to preserve errno where needed.

PathNameOpenFile failed to ensure that the correct value of errno was
returned to its caller after a failure (because it incorrectly supposed
that free() can never change errno).  In some cases this would result
in a user-visible failure because an expected ENOENT errno was replaced
with something else.  Bogus EINVAL failures have been observed on OS X,
for example.

There were also a couple of places that could mangle an important value
of errno if FDDEBUG was defined.  While the usefulness of that debug
support is highly debatable, we might as well make it safe to use,
so add errno save/restore logic to the DO_DB macro.

Per bug #8167 from Nelson Minar, diagnosed by RhodiumToad.
Back-patch to all supported branches.