XidEpoch++ if wraparound during checkpoint.
If wal_level = hot_standby we update the checkpoint nextxid,
though in the case where a wraparound occurred half-way through
a checkpoint we would neglect updating the epoch also. Updating
the nextxid is arguably the wrong thing to do, but changing that
may introduce subtle bugs into hot standby startup, while updating
the value doesn't cause any known bugs yet. Minimal fix now to
HEAD and backbranches, wider fix later in HEAD.

Bug reported in #6291 by Daniel Farina and slightly differently in

Cause analysis and recommended fixes from Tom Lane and Andres Freund.

Applied patch is minimal version of Andres Freund's work.
Rearrange storage of data in xl_running_xacts.
Previously we stored all xids mixed together.
Now we store top-level xids first, followed
by all subxids. Also skip logging any subxids
if the snapshot is suboverflowed, since there
are potentially large numbers of them and they
are not useful in that case anyway. Has value
in the envisaged design for decoding of WAL.
No planned effect on Hot Standby.

Andres Freund, reviewed by me
Don't advance checkPoint.nextXid near the end of a checkpoint sequence.

This reverts commit c11130690d6dca64267201a169cfb38c1adec5ef in favor of
actually fixing the problem: namely, that we should never have been
modifying the checkpoint record's nextXid at this point to begin with.
The nextXid should match the state as of the checkpoint's logical WAL
position (ie the redo point), not the state as of its physical position.
It's especially bogus to advance it in some wal_levels and not others.
In any case there is no need for the checkpoint record to carry the
same nextXid shown in the XLOG_RUNNING_XACTS record just emitted by
LogStandbySnapshot, as any replay operation will already have adopted
that value as current.

This fixes bug #7710 from Tarvi Pillessaar, and probably also explains bug
#6291 from Daniel Farina, in that if a checkpoint were in progress at the
instant of XID wraparound, the epoch bump would be lost as reported.
(And, of course, these days there's at least a 50-50 chance of a checkpoint
being in progress at any given instant.)

Diagnosed by me and independently by Andres Freund.  Back-patch to all
branches supporting hot standby.
Reduce scope of changes for COPY FREEZE.
Allow support only for freezing tuples by explicit
command. Previous coding mistakenly extended
slightly beyond what was agreed as correct on -hackers.
So essentially a partial revoke of earlier work,
leaving just the COPY FREEZE command.
Recommend triggers, not rules, in the CREATE VIEW reference page.

We've generally recommended use of INSTEAD triggers over rules since that
feature was added; but this old text in the CREATE VIEW reference page
didn't get the memo.  Noted by Thomas Kellerer.
Update time zone data files to tzdata release 2012j.

DST law changes in Cuba, Israel, Jordan, Libya, Palestine, Western Samoa,
and portions of Brazil.
Add mode where contrib installcheck runs each module in a separately named database.

Normally each module is tested in aq database named contrib_regression,
which is dropped and recreated at the beginhning of each pg_regress run.
This mode, enabled by adding USE_MODULE_DB=1 to the make command line,
runs most modules in a database with the module name embedded in it.

This will make testing pg_upgrade on clusters with the contrib modules
a lot easier.

Still to be done: adapt to the MSVC build system.

Backpatch to 9.0, which is the earliest version it is reasonably possible
to test upgrading from.
Refactor the code implementing standby-mode logic.

It is now easier to see that it's a state machine, making the code easier
to understand overall.
Clarify when to use PageSetLSN/PageGetLSN().
Update README to explain prerequisites for
correct access to LSN fields of a page.
Independent chunk removed from checksums
patch to reduce size of patch.
Clarify locking for PageGetLSN() in XLogCheckBuffer()
Refactor inCommit flag into generic delayChkpt flag.
Rename PGXACT->inCommit flag into delayChkpt flag,
and generalise comments to allow use in other situations,
such as the forthcoming potential use in checksum patch.
Replace wait loop to look for VXIDs with delayChkpt set.
No user visible changes, not behaviour changes at present.

Simon Riggs, reviewed and rebased by Jeff Davis
Attempt to unbreak MSVC builds broken by f21bb9cfb5646e1793dcc9c0ea697bab99afa523.

We can't use type uint, so use uint32.
Fix documentation of path(polygon) function.

Obviously, this returns type "path", but somebody made a copy-and-pasteo
long ago.

Dagfinn Ilmari Mannsåker
Avoid holding vmbuffer pin after VACUUM.
During VACUUM if we pause to perform a cycle
of index cleanup we drop the vmbuffer pin,
so we should do the same thing when heap
scan completes. This avoids holding vmbuffer
pin across the main index cleanup in VACUUM,
which could be minutes or hours longer than
necessary for correctness.

Bug report and suggested fix from Pavan Deolasee
Revert "Add mode where contrib installcheck runs each module in a separately named database."

This reverts commit e2b3c21b05c78c3a726b189242e41d4aa4422bf1.
Update release notes for 9.2.2, 9.1.7, 9.0.11, 8.4.15, 8.3.22.
In pg_upgrade, fix bug where no users were dumped in pg_dumpall
binary-upgrade mode;  instead only skip dumping the current user.

This bug was introduced in during the removal of split_old_dump().  Bug
discovered during local testing.
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