No catalog bump as the catalog changes are for SQL operator comments.

Backpatch through 9.5

The postmaster now checks every minute or so (worst case, at most two
minutes) that postmaster.pid is still there and still contains its own PID.
If not, it performs an immediate shutdown, as though it had received
SIGQUIT.

The original goal behind this change was to ensure that failed buildfarm
runs would get fully cleaned up, even if the test scripts had left a
postmaster running, which is not an infrequent occurrence.  When the
buildfarm script removes a test postmaster's $PGDATA directory, its next
check on postmaster.pid will fail and cause it to exit.  Previously, manual
intervention was often needed to get rid of such orphaned postmasters,
since they'd block new test postmasters from obtaining the expected socket
address.

However, by checking postmaster.pid and not something else, we can provide
additional robustness: manual removal of postmaster.pid is a frequent DBA
mistake, and now we can at least limit the damage that will ensue if a new
postmaster is started while the old one is still alive.

Back-patch to all supported branches, since we won't get the desired
improvement in buildfarm reliability otherwise.

Prior to commit 0709b7ee, access to
variables within a spinlock-protected critical section had to be done
through a volatile pointer, but that should no longer be necessary.
This continues work begun in df4077cd
and 6ba4ecbf.

Thomas Munro and Michael Paquier

Also, process constraints for LIKEd tables at the end so an OID column
can be referenced in a constraint.

Report by Tom Lane

to_char('V') already multiplied in a similar manner.

Report by Jeremy Lowery

Report by David G. Johnston

For time masks, like HH24, MI, SS, CC, MM, do not count the negative
sign as part of the zero-padding length specified by the mask, e.g. have
to_char('-4 years'::interval, 'YY') return '-04', not '-4'.

Report by Craig Ringer

Report by Tomas Vondra

Backpatch through 9.5

Failure to perform garbage collection now has a user-visible effect, so
explain that and explain that reducing pgss_max is the way to prevent it.
Per gripe from Andrew Dunstan.

Some of the buildfarm members are evidently miserly enough of stack space
to pass the originally-committed form of this test.  Increase the
requirement 10X to hopefully ensure that it fails as-expected everywhere.

Security: CVE-2015-5289

Add entries for security and not-quite-security issues.

Security: CVE-2015-5288, CVE-2015-5289

The documentation for the autovacuum_multixact_freeze_max_age and
autovacuum_freeze_max_age relation level parameters contained:
"Note that while you can set autovacuum_multixact_freeze_max_age very
small, or even zero, this is usually unwise since it will force frequent
vacuuming."
which hasn't been true since these options were made relation options,
instead of residing in the pg_autovacuum table (834a6da4).

Remove the outdated sentence. Even the lowered limits from 2596d705 are
high enough that this doesn't warrant calling out the risk in the CREATE
TABLE docs.

Per discussion with Tom Lane and Alvaro Herrera

Discussion: 26377.1443105453@sss.pgh.pa.us
Backpatch: 9.0- (in parts)

This adds regressions tests which are specific to INSERT+RETURNING and
UPDATE+RETURNING to ensure that the SELECT policies are added as
WithCheckOptions (and should therefore throw an error when the policy is
violated).

Per suggestion from Andres.

Back-patch to 9.5 as the prior commit was.

The tsquery, ltxtquery and query_int data types have a common ancestor.
Having acquired check_stack_depth() calls independently, each was
missing at least one call.  Back-patch to 9.0 (all supported versions).

A range type can name another range type as its subtype, and a record
type can bear a column of another record type.  Consequently, functions
like range_cmp() and record_recv() are recursive.  Functions at risk
include operator family members and referents of pg_type regproc
columns.  Treat as recursive any such function that looks up and calls
the same-purpose function for a record column type or the range subtype.
Back-patch to 9.0 (all supported versions).

An array type's element type is never itself an array type, so array
functions are unaffected.  Recursion depth proportional to array
dimensionality, found in array_dim_to_jsonb(), is fine thanks to MAXDIM.

Sufficiently-deep recursion heretofore elicited a SIGSEGV.  If an
application constructs PostgreSQL json or jsonb values from arbitrary
user input, application users could have exploited this to terminate all
active database connections.  That applies to 9.3, where the json parser
adopted recursive descent, and later versions.  Only row_to_json() and
array_to_json() were at risk in 9.2, both in a non-security capacity.
Back-patch to 9.2, where the json type was introduced.

Oskari Saarenmaa, reviewed by Michael Paquier.

Security: CVE-2015-5289

Certain short salts crashed the backend or disclosed a few bytes of
backend memory.  For existing salt-induced error conditions, emit a
message saying as much.  Back-patch to 9.0 (all supported versions).

Josh Kupershmidt

Security: CVE-2015-5288

Similar to 7d8db3e8, given that INSERT+RETURNING requires SELECT rights
on the table, apply the SELECT policies as WCOs to the tuples being
inserted.  Apply the same logic to UPDATE+RETURNING.

Back-patch to 9.5 where RLS was added.

The WithCheckOptions list in Query are only populated during rewrite and
do not need to be written out or read in as part of a Query structure.

Further, move WithCheckOptions to the bottom and add comments to clarify
that it is only populated during rewrite.

Back-patch to 9.5 with a catversion bump, as we are still in alpha.

In 020235a5 I lowered the autovacuum_*freeze_max_age minimums to
allow for easier testing of wraparounds. I did not touch the
corresponding per-table limits. While those don't matter for the purpose
of wraparound, it seems more consistent to lower them as well.

It's noteworthy that the previous reloption lower limit for
autovacuum_multixact_freeze_max_age was too high by one magnitude, even
before 020235a5.

Discussion: 26377.1443105453@sss.pgh.pa.us
Backpatch: back to 9.0 (in parts), like the prior patch

To allow users to force RLS to always be applied, even for table owners,
add ALTER TABLE .. FORCE ROW LEVEL SECURITY.

row_security=off overrides FORCE ROW LEVEL SECURITY, to ensure pg_dump
output is complete (by default).

Also add SECURITY_NOFORCE_RLS context to avoid data corruption when
ALTER TABLE .. FORCE ROW SECURITY is being used. The
SECURITY_NOFORCE_RLS security context is used only during referential
integrity checks and is only considered in check_enable_rls() after we
have already checked that the current user is the owner of the relation
(which should always be the case during referential integrity checks).

Back-patch to 9.5 where RLS was added.

If we can't read the query texts file (whether because out-of-memory, or
for some other reason), give up and reset the file to empty, discarding all
stored query texts, though not the statistics per se.  We used to leave
things alone and hope for better luck next time, but the problem is that
the file is only going to get bigger and even harder to slurp into memory.
Better to do something that will get us out of trouble.

Likewise reset the file to empty for any other failure within gc_qtexts().
The previous behavior after a write error was to discard query texts but
not do anything to truncate the file, which is just weird.

Also, increase the maximum supported file size from MaxAllocSize to
MaxAllocHugeSize; this makes it more likely we'll be able to do a garbage
collection successfully.

Also, fix recalculation of mean_query_len within entry_dealloc() to match
the calculation in gc_qtexts().  The previous coding overlooked the
possibility of dropped texts (query_len == -1) and would underestimate the
mean of the remaining entries in such cases, thus possibly causing excess
garbage collection cycles.

In passing, add some errdetail to the log entry that complains about
insufficient memory to read the query texts file, which after all was
Jim Nasby's original complaint.

Back-patch to 9.4 where the current handling of query texts was
introduced.

Peter Geoghegan, rather editorialized upon by me

Due to b67aaf21 / CREATE EXTENSION ... CASCADE the test output
contains the extension name in yet another place. Since that's variable
depending on the python version...

Add yet another name mangling stanza to regress-python3-mangle.mk.

Author: Petr Jelinek

On reflection, the submitted patch didn't really work to prevent the
request size from exceeding MaxAllocSize, because of the fact that we'd
happily round nbuckets up to the next power of 2 after we'd limited it to
max_pointers.  The simplest way to enforce the limit correctly is to
round max_pointers down to a power of 2 when it isn't one already.

(Note that the constraint to INT_MAX / 2, if it were doing anything useful
at all, is properly applied after that.)

Limit the size of the hashtable pointer array to not more than
MaxAllocSize, per reports from Kouhei Kaigai and others of "invalid memory
alloc request size" failures.  There was discussion of allowing the array
to get larger than that by using the "huge" palloc API, but so far no proof
that that is actually a good idea, and at this point in the 9.5 cycle major
changes from old behavior don't seem like the way to go.

Fix a rather serious secondary bug in the new code, which was that it
didn't ensure nbuckets remained a power of 2 when recomputing it for the
multiple-batch case.

Clean up sloppy division of labor between ExecHashIncreaseNumBuckets and
its sole call site.

Null path elements and, where the object is an array, invalid integer
elements now cause an error.

Incorrect behaviour noted by Thom Brown, patch from Dmitry Dolgov.

Backpatch to 9.5 where jsonb_set was introduced

Oversight in commit 537bd178.
Back-patch to 9.5, like that commit.

Specifically, make its effect independent from the row_security GUC, and
make it affect permission checks pertinent to views the BYPASSRLS role
owns.  The row_security GUC thereby ceases to change successful-query
behavior; it can only make a query fail with an error.  Back-patch to
9.5, where BYPASSRLS was introduced.

Without CASCADE, if an extension has an unfullfilled dependency on
another extension, CREATE EXTENSION ERRORs out with "required extension
... is not installed". That is annoying, especially when that dependency
is an implementation detail of the extension, rather than something the
extension's user can make sense of.

In addition to CASCADE this also includes a small set of regression
tests around CREATE EXTENSION.

Author: Petr Jelinek, editorialized by Michael Paquier, Andres Freund
Reviewed-By: Michael Paquier, Andres Freund, Jeff Janes
Discussion: 557E0520.3040800@2ndquadrant.com

Per buildfarm (pademelon, at least, doesn't like this).

The existing hint talked about "may only contain letters", but the
actual requirement is more strict: only lower case letters are allowed.

Reported-By: Rushabh Lathia
Author: Rushabh Lathia
Discussion: AGPqQf2x50qcwbYOBKzb4x75sO_V3g81ZsA8+Ji9iN5t_khFhQ@mail.gmail.com
Backpatch: 9.4-, where replication slots were added

Four related issues:

1) attnos/varnos/resnos for EXCLUDED were out of sync when a column
   after one dropped in the underlying relation was referenced.
2) References to whole-row variables (i.e. EXCLUDED.*) lead to errors.
3) It was possible to reference system columns in the EXCLUDED pseudo
   relations, even though they would not have valid contents.
4) References to EXCLUDED were rewritten by the RLS machinery, as
   EXCLUDED was treated as if it were the underlying relation.

To fix the first two issues, generate the excluded targetlist with
dropped columns in mind and add an entry for whole row
variables. Instead of unconditionally adding a wholerow entry we could
pull up the expression if needed, but doing it unconditionally seems
simpler. The wholerow entry is only really needed for ruleutils/EXPLAIN
support anyway.

The remaining two issues are addressed by changing the EXCLUDED RTE to
have relkind = composite. That fits with EXCLUDED not actually being a
real relation, and allows to treat it differently in the relevant
places. scanRTEForColumn now skips looking up system columns when the
RTE has a composite relkind; fireRIRrules() already had a corresponding
check, thereby preventing RLS expansion on EXCLUDED.

Also add tests for these issues, and improve a few comments around
excluded handling in setrefs.c.

Reported-By: Peter Geoghegan, Geoff Winkless
Author: Andres Freund, Amit Langote, Peter Geoghegan
Discussion: CAEzk6fdzJ3xYQZGbcuYM2rBd2BuDkUksmK=mY9UYYDugg_GgZg@mail.gmail.com,
   CAM3SWZS+CauzbiCEcg-GdE6K6ycHE_Bz6Ksszy8AoixcMHOmsA@mail.gmail.com
Backpatch: 9.5, where ON CONFLICT was introduced

DST law changes in Cayman Islands, Fiji, Moldova, Morocco, Norfolk Island,
North Korea, Turkey, Uruguay.  New zone America/Fort_Nelson for Canadian
Northern Rockies.