Fix uninitialized-variable warning.

In passing, add an Assert defending the presumption that bytes_left
is positive to start with.  (I'm not exactly convinced that using an
unsigned type was such a bright thing here, but let's at least do
this much.)
Remove extraneous SGML tag
Attempt to suppress uninitialized variable warning.

Report by Heikki Linnakangas.
doc: Fix markup
Remove dead function prototype

It was added in commit efc16ea5, but never defined.
Rename pg_rowsecurity -> pg_policy and other fixes

As pointed out by Robert, we should really have named pg_rowsecurity
pg_policy, as the objects stored in that catalog are policies.  This
patch fixes that and updates the column names to start with 'pol' to
match the new catalog name.

The security consideration for COPY with row level security, also
pointed out by Robert, has also been addressed by remembering and
re-checking the OID of the relation initially referenced during COPY
processing, to make sure it hasn't changed under us by the time we
finish planning out the query which has been built.

Robert and Alvaro also commented on missing OCLASS and OBJECT entries
for POLICY (formerly ROWSECURITY or POLICY, depending) in various
places.  This patch fixes that too, which also happens to add the
ability to COMMENT on policies.

In passing, attempt to improve the consistency of messages, comments,
and documentation as well.  This removes various incarnations of
'row-security', 'row-level security', 'Row-security', etc, in favor
of 'policy', 'row level security' or 'row_security' as appropriate.

Happy Thanksgiving!
Free libxml2/libxslt resources in a safer order.

Mark Simonetti reported that libxslt sometimes crashes for him, and that
swapping xslt_process's object-freeing calls around to do them in reverse
order of creation seemed to fix it.  I've not reproduced the crash, but
valgrind clearly shows a reference to already-freed memory, which is
consistent with the idea that shutdown of the xsltTransformContext is
trying to reference the already-freed stylesheet or input document.
With this patch, valgrind is no longer unhappy.

I have an inquiry in to see if this is a libxslt bug or if we're just
abusing the library; but even if it's a library bug, we'd want to adjust
our code so it doesn't fail with unpatched libraries.

Back-patch to all supported branches, because we've been doing this in
the wrong(?) order for a long time.
Mark response messages for translation in pg_isready.

Back-patch to 9.3 where pg_isready was added.

Mats Erik Andersson
Make \watch respect the user's \pset null setting.

Previously \watch always ignored the user's \pset null setting.
\pset null setting should be ignored for \d and similar queries.
For those, the code can reasonably have an opinion about what
the presentation should be like, since it knows what SQL query
it's issuing. This argument surely doesn't apply to \watch,
so this commit makes \watch use the user's \pset null setting.

Back-patch to 9.3 where \watch was added.
Fix assertion failure at end of PITR.

InitXLogInsert() cannot be called in a critical section, because it
allocates memory. But CreateCheckPoint() did that, when called for the
end-of-recovery checkpoint by the startup process.

In the passing, fix the scratch space allocation in InitXLogInsert to go to
the right memory context. Also update the comment at InitXLOGAccess, which
hasn't been totally accurate since hot standby was introduced (in a hot
standby backend, InitXLOGAccess isn't called at backend startup).

Reported by Michael Paquier
Add tab-completion for ALTER TABLE ALTER CONSTRAINT in psql.

Back-patch to 9.4 where ALTER TABLE ALTER CONSTRAINT was added.

Michael Paquier, bug reported by Andrey Lizenko.
Improve typcache: cache negative lookup results, add invalidation logic.

Previously, if the typcache had for example tried and failed to find a hash
opclass for a given data type, it would nonetheless repeat the unsuccessful
catalog lookup each time it was asked again.  This can lead to a
significant amount of useless bufmgr traffic, as in a recent report from
Scott Marlowe.  Like the catalog caches, typcache should be able to cache
negative results.  This patch arranges that by making use of separate flag
bits to remember whether a particular item has been looked up, rather than
treating a zero OID as an indicator that no lookup has been done.

Also, install a credible invalidation mechanism, namely watching for inval
events in pg_opclass.  The sole advantage of the lack of negative caching
was that the code would cope if operators or opclasses got added for a type
mid-session; to preserve that behavior we have to be able to invalidate
stale lookup results.  Updates in pg_opclass should be pretty rare in
production systems, so it seems sufficient to just invalidate all the
dependent data whenever one happens.

Adding proper invalidation also means that this code will now react sanely
if an opclass is dropped mid-session.  Arguably, that's a back-patchable
bug fix, but in view of the lack of complaints from the field I'll refrain
from back-patching.  (Probably, in most cases where an opclass is dropped,
the data type itself is dropped soon after, so that this misfeasance has
no bad consequences.)
Improve performance of OverrideSearchPathMatchesCurrent().

This function was initially coded on the assumption that it would not be
performance-critical, but that turns out to be wrong in workloads that
are heavily dependent on the speed of plpgsql functions.  Speed it up by
hard-coding the comparison rules, thereby avoiding palloc/pfree traffic
from creating and immediately freeing an OverrideSearchPath object.
Per report from Scott Marlowe.
Add bms_next_member(), and use it where appropriate.

This patch adds a way of iterating through the members of a bitmapset
nondestructively, unlike the old way with bms_first_member().  While
bms_next_member() is very slightly slower than bms_first_member()
(at least for typical-size bitmapsets), eliminating the need to palloc
and pfree a temporary copy of the target bitmapset is a significant win.
So this method should be preferred in all cases where a temporary copy
would be necessary.

Tom Lane, with suggestions from Dean Rasheed and David Rowley
Add bms_get_singleton_member(), and use it where appropriate.

This patch adds a function that replaces a bms_membership() test followed
by a bms_singleton_member() call, performing both the test and the
extraction of a singleton set's member in one scan of the bitmapset.
The performance advantage over the old way is probably minimal in current
usage, but it seems worthwhile on notational grounds anyway.

David Rowley
Update transaction README for persistent multixacts

Multixacts are now maintained during recovery, but the README didn't get
the memo.  Backpatch to 9.3, where the divergence was introduced.
Fix BRIN operator family definitions

The original definitions were leaving no room for cross-type operators,
so queries that compared a column of one type against something of a
different type were not taking advantage of the index.  Fix by making
the opfamilies more like the ones for Btree, and include a few
cross-type operator classes.

Catalog version bumped.

Per complaints from Hubert Lubaczewski, Mark Wong, Heikki Linnakangas.