Add CheckTableNotInUse calls in DROP TABLE and DROP INDEX.

Recent releases had a check on rel->rd_refcnt in heap_drop_with_catalog,
but failed to cover the possibility of pending trigger events at DROP time.
(Before 8.4 we didn't even check the refcnt.)  When the trigger events were
eventually fired, you'd get "could not open relation with OID nnn" errors,
as in recent report from strk.  Better to throw a suitable error when the
DROP is attempted.

Also add a similar check in DROP INDEX.

Back-patch to all supported branches.
Fix dangling-pointer problem in before-row update trigger processing.

ExecUpdate checked for whether ExecBRUpdateTriggers had returned a new
tuple value by seeing if the returned tuple was pointer-equal to the old
one.  But the "old one" was in estate->es_junkFilter's result slot, which
would be scribbled on if we had done an EvalPlanQual update in response to
a concurrent update of the target tuple; therefore we were comparing a
dangling pointer to a live one.  Given the right set of circumstances we
could get a false match, resulting in not forcing the tuple to be stored in
the slot we thought it was stored in.  In the case reported by Maxim Boguk
in bug #5798, this led to "cannot extract system attribute from virtual
tuple" failures when trying to do "RETURNING ctid".  I believe there is a
very-low-probability chance of more serious errors, such as generating
incorrect index entries based on the original rather than the
trigger-modified version of the row.

In HEAD, change all of ExecBRInsertTriggers, ExecIRInsertTriggers,
ExecBRUpdateTriggers, and ExecIRUpdateTriggers so that they continue to
have similar APIs.  In the back branches I just changed
ExecBRUpdateTriggers, since there is no bug in the ExecBRInsertTriggers
case.
Put in some more safeguards against executing a division-by-zero.

Add dummy returns before every potential division-by-zero in int8.c,
because apparently further "improvements" in gcc's optimizer have
enabled it to break functions that weren't broken before.

Aurelien Jarno, via Martin Pitt
On further reflection, we'd better do the same in int.c.

We previously heard of the same problem in int24div(), so there's not a
good reason to suppose the problem is confined to cases involving int8.
Use correct PATH separator for Cygwin in pg_regress.c.

This has been broken for years, and I'm not sure why it has not been
noticed before, but now a very modern Cygwin breaks on it, and the fix
is clearly correct. Backpatching to all live branches.
Fix PL/Python memory leak involving array slices

Report and patch from Daniel Popowich, bug #5842
(with some debugging help from Alex Hunsaker)
Avoid potential deadlock in InitCatCachePhase2().

Opening a catcache's index could require reading from that cache's own
catalog, which of course would acquire AccessShareLock on the catalog.
So the original coding here risks locking index before heap, which could
deadlock against another backend trying to get exclusive locks in the
normal order.  Because InitCatCachePhase2 is only called when a backend
has to start up without a relcache init file, the deadlock was seldom seen
in the field.  (And by the same token, there's no need to worry about any
performance disadvantage; so not much point in trying to distinguish
exactly which catalogs have the risk.)

Bug report, diagnosis, and patch by Nikhil Sontakke.  Additional commentary
by me.  Back-patch to all supported branches.
Fix ancient typo in user-defined-aggregates documentation.

The description of the initcond value for the built-in avg(float8)
aggregate has been wrong since it was written.  Noted by Disc Magnet.
Improve user-defined-aggregates documentation.

On closer inspection, that two-element initcond value seems to have been
a little white lie to avoid explaining the full behavior of float8_accum.
But if people are going to expect the examples to be exactly correct,
I suppose we'd better explain.  Per comment from Thom Brown.
Correct "characters" to "bytes" in createdb docs.

Susanne Ebrecht
Prevent a rowtype from being included in itself.

Eventually we might be able to allow that, but it's not clear how many
places need to be fixed to prevent infinite recursion when there's a direct
or indirect inclusion of a rowtype in itself.  One such place is
CheckAttributeType(), which will recurse to stack overflow in cases such as
those exhibited in bug #5950 from Alex Perepelica.  If we were sure it was
the only such place, we could easily modify the code added by this patch to
stop the recursion without a complaint ... but it probably isn't the only
such place.  Hence, throw error until such time as someone is excited
enough about this type of usage to put work into making it safe.

Back-patch as far as 8.3.  8.2 doesn't have the recursive call in
CheckAttributeType in the first place, so I see no need to add code there
in the absence of clear evidence of a problem elsewhere.
Fix SortTocFromFile() to cope with lines that are too long for its buffer.

The original coding supposed that a dump TOC file could never contain lines
longer than 1K.  The folly of that was exposed by a recent report from
Per-Olov Esgard.  We only really need to see the first dozen or two bytes
of each line, since we're just trying to read off the numeric ID at the
start of the line; so there's no need for a particularly huge buffer.
What there is a need for is logic to not process continuation bufferloads.

Back-patch to all supported branches, since it's always been like this.
Modernize dlopen interface code for FreeBSD and OpenBSD.

Remove the hard-wired assumption that __mips__ (and only __mips__) lacks
dlopen in FreeBSD and OpenBSD.  This assumption is outdated at least for
OpenBSD, as per report from an anonymous 9.1 tester.  We can perfectly well
use HAVE_DLOPEN instead to decide which code to use.

Some other cosmetic adjustments to make freebsd.c, netbsd.c, and openbsd.c
exactly alike.
Avoid use of mixed slash style paths in arguments to xcopy in MSVC builds.

Some versions of xcopy, notably on Windows 7 don't like it. Backpatch
to 8.3, where we first used xcopy.
On IA64 architecture, we check the depth of the register stack in addition
to the regular stack. The code to do that is platform and compiler specific,
add support for the HP-UX native compiler.
Update time zone data files to tzdata release 2011f.

DST law changes in Chile, Cuba, Falkland Islands, Morocco, Samoa, Turkey.
Historical corrections for South Australia, Alaska, Hawaii.
Update release notes for releases 9.0.4, 8.4.8, 8.3.15, and 8.2.21.
Translation updates
Tag 8.3.15.
Prevent incorrect updates of pg_index while reindexing pg_index itself.

The places that attempt to change pg_index.indcheckxmin during a reindexing
operation cannot be executed safely if pg_index itself is the subject of
the operation.  This is the explanation for a couple of recent reports of
VACUUM FULL failing with
	ERROR:  duplicate key value violates unique constraint "pg_index_indexrelid_index"
	DETAIL:  Key (indexrelid)=(2678) already exists.

However, there isn't any real need to update indcheckxmin in such a
situation, if we assume that pg_index can never contain a truly broken HOT
chain.  This assumption holds if new indexes are never created on it during
concurrent operations, which is something we don't consider safe for any
system catalog, not just pg_index.  Accordingly, modify the code to not
manipulate indcheckxmin when reindexing any system catalog.

Back-patch to 8.3, where HOT was introduced.  The known failure scenarios
involve 9.0-style VACUUM FULL, so there might not be any real risk before
9.0, but let's not assume that.