Merge branch 'master' into test
Commit
Correctly handle NULLs in JSON output.

Error reported by David Wheeler.
Fix the general case of quantified regex back-references.

Cases where a back-reference is part of a larger subexpression that
is quantified have never worked in Spencer's regex engine, because
he used a compile-time transformation that neglected the need to
check the back-reference match in iterations before the last one.
(That was okay for capturing parens, and we still do it if the
regex has *only* capturing parens ... but it's not okay for backrefs.)

To make this work properly, we have to add an "iteration" node type
to the regex engine's vocabulary of sub-regex nodes.  Since this is a
moderately large change with a fair risk of introducing new bugs of its
own, apply to HEAD only, even though it's a fix for a longstanding bug.
Add some enumeration commas, for consistency
Put Debian package list back in alphabetical order
Update src/tools/make_ctags to avoid Exuberant tags option
that has been renamed and undocumented since 2003;  instead, use the
documented option.  Add comments.
Mention original ctags option name.
Remove useless "retry memory" logic within regex engine.

Apparently some primordial version of Spencer's engine needed cdissect()
and child functions to be able to continue matching from a previous
position when re-called.  That is dead code, though, since trivial
inspection shows that cdissect can never be entered without having
previously done zapmem which resets the relevant retry counter.  I have
also verified experimentally that no case in the Tcl regression tests
reaches cdissect with a nonzero retry value.  Accordingly, remove that
logic.  This doesn't really save any noticeable number of cycles in itself,
but it is one step towards making dissect() and cdissect() equivalent,
which will allow removing hundreds of lines of near-duplicated code.

Since struct subre's "retry" field is no longer particularly related to
any kind of retry, rename it to "id".  As of this commit it's only used
for identifying a subre node in debug printouts, so you might think we
should get rid of the field entirely; but I have a plan for another use.
Avoid repeated creation/freeing of per-subre DFAs during regex search.

In nested sub-regex trees, lower-level nodes created DFAs and then
destroyed them again before exiting, which is a bit dumb considering that
the recursive search is likely to call those nodes again later.  Instead
cache each created DFA until the end of pg_regexec().  This is basically a
space for time tradeoff, in that it might increase the maximum memory
usage.  However, in most regex patterns there are not all that many subre
nodes, so not that many DFAs --- and in any case, the peak usage occurs
when reaching the bottom recursion level, and except for alternation cases
that's going to be the same anyway.
Merge dissect() into cdissect() to remove a pile of near-duplicate code.

The "uncomplicated" case isn't materially less complicated than the full
case, certainly not enough so to justify duplicating nearly 500 lines
of code.  The only extra work being done in the full path is zaptreesubs,
which is very cheap compared to everything else being done here, and
besides that I'm less than convinced that it's not needed in some cases
even without backrefs.
Make each pg_stat_ view into it's own table in the documentation

This makes it easier to match a column name with the description of it,
and makes it possible to add more detailed documentation in the future.

This patch does not add that extra documentation at this point, only
the structure required for it.

Modeled on the changes already done to pg_stat_activity.
Merge the list of statistics functions into the view documentation

Most people won't read them individually anyway, it's an easy way to find
them, and it's a lot of duplicated information if they are kept in two
different places.
Fix some typos and correct wording in the monitoring docs patch

Thom Brown
Remove useless const qualifier

Claiming that the typevar argument to DefineCompositeType() is const
was a plain lie.  A similar case in DefineVirtualRelation() was
already changed in passing in commit 1575fbcb.  Also clean up the now
unnecessary casts that used to cast away the const.
Remove useless cast
Fix some more bugs in GIN's WAL replay logic.

In commit 4016bdef8aded77b4903c457050622a5a1815c16 I fixed a bunch of
ginxlog.c bugs having to do with not handling XLogReadBuffer failures
correctly.  However, in ginRedoUpdateMetapage and ginRedoDeleteListPages,
I unaccountably thought that failure to read the metapage would be
impossible and just put in an elog(PANIC) call.  This is of course wrong:
failure is exactly what will happen if the index got dropped (or rebuilt)
between creation of the WAL record and the crash we're trying to recover
from.  I believe this explains Nicholas Wilson's recent report of these
errors getting reached.

Also, fix memory leak in forgetIncompleteSplit.  This wasn't of much
concern when the code was written, but in a long-running standby server
page split records could be expected to accumulate indefinitely.

Back-patch to 8.4 --- before that, GIN didn't have a metapage.
Call check_keywords.pl in maintainer-check

For that purpose, have check_keywords.pl print errors to stderr and
return a useful exit status.
ALTER TABLE: skip FK validation when it's safe to do so

We already skip rewriting the table in these cases, but we still force a
whole table scan to validate the data.  This can be skipped, and thus
we can make the whole ALTER TABLE operation just do some catalog touches
instead of scanning the table, when these two conditions hold:

(a) Old and new pg_constraint.conpfeqop match exactly.  This is actually
stronger than needed; we could loosen things by way of operator
families, but it'd require a lot more effort.

(b) The functions, if any, implementing a cast from the foreign type to
the primary opcintype are the same.  For this purpose, we can consider a
binary coercion equivalent to an exact type match.  When the opcintype
is polymorphic, require that the old and new foreign types match
exactly.  (Since ri_triggers.c does use the executor, the stronger check
for polymorphic types is no mere future-proofing.  However, no core type
exercises its necessity.)

Author: Noah Misch

Committer's note: catalog version bumped due to change of the Constraint
node.  I can't actually find any way to have such a node in a stored
rule, but given that we have "out" support for them, better be safe.
psql: when tab-completing, use quotes on file names that need them

psql backslash commands that deal with file or directory names require
quotes around those that have spaces, single quotes, or backslashes.
However, tab-completing such names does not provide said quotes, and is
thus almost useless with them.

This patch fixes the problem by having a wrapper function around
rl_filename_completion_function that dequotes on input and quotes on
output.  This eases dealing with such names.

Author: Noah Misch