The previous functions of assign hooks are now split between check hooks
and assign hooks, where the former can fail but the latter shouldn't.
Aside from being conceptually clearer, this approach exposes the
"canonicalized" form of the variable value to guc.c without having to do
an actual assignment.  And that lets us fix the problem recently noted by
Bernd Helmle that the auto-tune patch for wal_buffers resulted in bogus
log messages about "parameter "wal_buffers" cannot be changed without
restarting the server".  There may be some speed advantage too, because
this design lets hook functions avoid re-parsing variable values when
restoring a previous state after a rollback (they can store a pre-parsed
representation of the value instead).  This patch also resolves a
longstanding annoyance about custom error messages from variable assign
hooks: they should modify, not appear separately from, guc.c's own message
about "invalid parameter value".

This mimics the traceback information the Python interpreter prints
with exceptions.

Jan Urbański

When we release and reacquire SerializableXactHashLock, we must recheck
whether an R/W conflict still needs to be flagged, because it could have
changed under us in the meantime.  And when we release the partition
lock, we must re-walk the list of predicate locks from the beginning,
because our pointer could get invalidated under us.

Bug report #5952 by Yamamoto Takashi.  Patch by Kevin Grittner.

Gabriele Bartolini

Erik Rijkers

Joey Adams, per gripe from Ramanujam.  Review by myself and Tom Lane.

Also avoid hardcoding the current default state by giving it the name
"on" and replace with a meaningful name that reflects its behaviour.
Coding only, no change in behaviour.

Per Robert Haas

This means one less thing to configure when setting up synchronous
replication, and also avoids some ambiguity around what the behavior
should be when the settings of these variables conflict.

Fujii Masao, with additional hacking by me.

This improves compatibility with external toolchains, such as those used
by some documentation translation tools.

Gabriele Bartolini

KaiGai Kohei

Dan Ports

The previous coding set attinhcount too high in some cases, resulting in
an undumpable, undroppable column.  Per bug #5856, reported by Naoya
Anzai.  See also commit 31b6fc06, which
fixes a similar bug in ALTER TABLE .. ADD CONSTRAINT.

Patch by Noah Misch.

Gianni Ciolli, reviewed by Noah Misch

This isn't applicable on Windows, and the internal link to the
psql documentation should be more than sufficient.

Susanne Ebrecht

If a smart shutdown occurs just as a child is starting up, and the
child subsequently becomes a walsender, there is a race condition:
the postmaster might count the exstant backends, determine that there
is one normal backend, and wait for it to die off.  Had the walsender
transition already occurred before the postmaster counted, it would
have proceeded with the shutdown.

To fix this, have each child that transforms into a walsender kick
the postmaster just after doing so, so that the state machine is
certain to advance.

Fujii Masao

This would lead to leaking the PGconn structure after an error detected by
conninfo_array_parse(), as well as failing to return a useful error message
in such cases.  Backpatch to 9.0 where the error was introduced.

Joseph Adams

Susanne Ebrecht and me

Instead, write the unconverted output - it will be in the wrong
encoding, but at least we don't crash.

Rushabh Lathia

Shigeru Hanada, with some corrections.

This mostly involves making it work with the objectaddress.c framework,
which does most of the heavy lifting.  In that vein, change
GetForeignDataWrapperOidByName to get_foreign_data_wrapper_oid and
GetForeignServerOidByName to get_foreign_server_oid, to match the
pattern we use for other object types.

Robert Haas and Shigeru Hanada

Josh Kupershmidt

examining the head of predicate locks list. Also, fix the comment of
RemoveTargetIfNoLongerUsed, it was neglected when we changed the way update
chains are handled.

Kevin Grittner

ShmemIndex, so 64 leaves some headroom.

Kevin Grittner

blocks.

Investigation by Jan Urbański, though I didn't use his patch.

archive recovery.

It's possible to restore an online backup without recovery.conf, by simply
copying all the necessary WAL files to pg_xlog. "pg_basebackup -x" does that
too. That's the use case where this cross-check is useful.

Backpatch to 9.0. We used to do this in earlier versins, but in 9.0 the code
was inadvertently changed so that the check is only performed after archive
recovery.

Fujii Masao.

than replication_timeout (a new GUC) milliseconds. The TCP timeout is often
too long, you want the master to notice a dead connection much sooner.
People complained about that in 9.0 too, but with synchronous replication
it's even more important to notice dead connections promptly.

Fujii Masao and Heikki Linnakangas