NOTICE-grade messages are not logged by default.  Per pgsql-hackers
discussion back on 21-Nov-2007.

With the addition of multiple autovacuum workers, our choices were to delete
the check, document the interaction with autovacuum_max_workers, or complicate
the check to try to hide that interaction.  Since this restriction has never
been adequate to ensure backends can't run out of pinnable buffers, it doesn't
really have enough excuse to live to justify the second or third choices.
Per discussion of a complaint from Andreas Kling (see also bug #3888).

This commit also removes several documentation references to this restriction,
but I'm not sure I got them all.

synchronized-scanning behavior, and make pg_dump disable sync scans so that
it will reliably preserve row ordering.  Per recent discussions.

in particular correct the obsolete claim that it can't be changed once
any plans have been cached.

during transaction abort, per my note from a couple days ago.

were reporting ERROR for interactive assignments and LOG for other cases,
some were saying nothing for non-interactive cases, and a few did yet other
things.  Make them use a new function GUC_complaint_elevel() to establish
a reasonably uniform policy about how to report.  There are still a few
edge cases such as assign_search_path(), but it's much better than before.
Per gripe from Devrim Gunduz and subsequent discussion.

As noted by Alvaro, it'd be better to fold these custom messages into the
standard "invalid parameter value" complaint from guc.c, perhaps as the DETAIL
field.  However that will require more redesign than seems prudent for 8.3.
This is a relatively safe, low-impact change that we can afford to risk now.

even in code paths where we don't pay any subsequent attention to the typmod
value.  This seems needed in view of the fact that 8.3's generalized typmod
support will accept a lot of bogus syntax, such as "timestamp(foo)" or
"record(int, 42)" --- if we allow such things to pass without comment,
users will get confused.  Per a recent example from Greg Stark.

To implement this in a way that's not very vulnerable to future
bugs-of-omission, refactor the API of parse_type.c's TypeName lookup routines
so that typmod validation is folded into the base lookup operation.  Callers
can still choose not to receive the encoded typmod, but we'll check the
decoration anyway if it's present.

to validate the realm of the connecting user. By default
it's empty meaning no verification, which is the way
Kerberos authentication has traditionally worked in
PostgreSQL.

- create a separate archive_mode GUC, on which archive_command is dependent

- %r option in recovery.conf sends last restartpoint to recovery command

- %r used in pg_standby, updated README

- minor other code cleanup in pg_standby

- doc on Warm Standby now mentions pg_standby and %r

- log_restartpoints recovery option emits LOG message at each restartpoint

- end of recovery now displays last transaction end time, as requested
  by Warren Little; also shown at each restartpoint

- restart archiver if needed to carry away WAL files at shutdown

Simon Riggs

buffers that cannot possibly need to be cleaned, and estimates how many
buffers it should try to clean based on moving averages of recent allocation
requests and density of reusable buffers.  The patch also adds a couple
more columns to pg_stat_bgwriter to help measure the effectiveness of the
bgwriter.

Greg Smith, building on his own work and ideas from several other people,
in particular a much older patch from Itagaki Takahiro.

* stats_start_collector goes away; we always start the collector process,
unless prevented by a problem with setting up the stats UDP socket.

* stats_reset_on_server_start goes away; it seems useless in view of the
availability of pg_stat_reset().

* stats_block_level and stats_row_level are merged into a single variable
"track_counts", which controls all reports sent to the collector process.

* stats_command_string is renamed to track_activities.

* log_autovacuum is renamed to log_autovacuum_min_duration to better reflect
its meaning.

The log_autovacuum change is not a compatibility issue since it didn't exist
before 8.3 anyway.  The other changes need to be release-noted.

transaction, unless rolled back or overridden by a SET clause for the same
variable attached to a surrounding function call.  Per discussion, these
seem the best semantics.  Note that this is an INCOMPATIBLE CHANGE: in 8.0
through 8.2, SET LOCAL's effects disappeared at subtransaction commit
(leading to behavior that made little sense at the SQL level).

I took advantage of the opportunity to rewrite and simplify the GUC variable
save/restore logic a little bit.  The old idea of a "tentative" value is gone;
it was a hangover from before we had a stack.  Also, we no longer need a stack
entry for every nesting level, but only for those in which a variable's value
actually changed.

Fix grammatical errors in its description.

and in passing, fix some bogosities dating from the custom_variable_classes
patch.  Fix guc-file.l to correctly check changes in custom_variable_classes
that are attempted concurrently with additions/removals of custom variables,
and don't allow the new setting to be applied in advance of checking it.
Clean up messy and undocumented situation for string variables with NULL
boot_val.  Fix DefineCustomVariable functions to initialize boot_val
correctly.  Prevent find_option from inserting bogus placeholders for custom
variables that are simply inquired about rather than being set.

(Actually, it works as a plain statement too, but I didn't document that
because it seems a bit useless.)  Unify VariableResetStmt with
VariableSetStmt, and clean up some ancient cruft in the representation of
same.

There are still some loose ends: I didn't do anything about the SET FROM
CURRENT idea yet, and it's not real clear whether we are happy with the
interaction of SET LOCAL with function-local settings.  The documentation
is a bit spartan, too.

Oleg Bartunov and Teodor Sigaev, but I did a lot of editorializing,
so anything that's broken is probably my fault.

Documentation is nonexistent as yet, but let's land the patch so we can
get some portability testing done.

redirect_stderr to logging_collector.
Original patch from Arul Shaji, subsequently modified by Greg Smith, and then
heavily modified by me.

thorough testing of async-commit mode from the buildfarm.  This patch MUST
get reverted before 8.3 release!

GUC assign hooks are supposed to be made whether doit is true or not.

between the setting of log_line_prefix and the setting of log_timezone.  We
can't realistically set log_timezone any earlier than we do now, so the best
behavior seems to be to use GMT zone if any timestamps are to be logged during
early startup.  Create a dummy zone variable with a minimal definition of GMT
(in particular it will never know about leap seconds), so that we can set it
up without reference to any external files.

displayed in the postmaster log.  This avoids Windows-specific problems with
localized time zone names that are in the wrong encoding, and generally seems
like a good idea to forestall other potential platform-dependent issues.
To preserve the existing behavior that all backends will log in the same time
zone, create a new GUC variable log_timezone that can only be changed on a
system-wide basis, and reference log-related calculations to that zone instead
of the TimeZone variable.

This fixes the issue reported by Hiroshi Saito that timestamps printed by
xlog.c startup could be improperly localized on Windows.  We still need a
simpler patch for that problem in the back branches, however.

before reporting a transaction committed.  Data consistency is still
guaranteed (unlike setting fsync = off), but a crash may lose the effects
of the last few transactions.  Patch by Simon, some editorialization by Tom.

and fsync WAL at convenient intervals.  For the moment it just tries to
offload this work from backends, but soon it will be responsible for
guaranteeing a maximum delay before asynchronously-committed transactions
will be flushed to disk.

This is a portion of Simon Riggs' async-commit patch, committed to CVS
separately because a background WAL writer seems like it might be a good idea
independently of the async-commit feature.  I rebased walwriter.c on
bgwriter.c because it seemed like a more appropriate way of handling signals;
while the startup/shutdown logic in postmaster.c is more like autovac because
we want walwriter to quit before we start the shutdown checkpoint.

I/O utilization, per discussion.

While at it, lower the autovacuum vacuum and analyze threshold values to 50
tuples.  It is a bit higher (i.e. more conservative) than what I originally
proposed but much better than the old values for small tables.

Documentation still being written, will be committed later.

Henry B. Hotz and Magnus Hagander

by Heikki and a little bit by me.

over a fairly long period of time, rather than being spat out in a burst.
This happens only for background checkpoints carried out by the bgwriter;
other cases, such as a shutdown checkpoint, are still done at full speed.

Remove the "all buffers" scan in the bgwriter, and associated stats
infrastructure, since this seems no longer very useful when the checkpoint
itself is properly throttled.

Original patch by Itagaki Takahiro, reworked by Heikki Linnakangas,
and some minor API editorialization by me.

parse_int() and with itself (strtod allows leading whitespace, so it
seems odd not to allow trailing whitespace).  parse_bool remains
not-whitespace-friendly, but this is generically true for non-numeric
GUC variables, so I'll desist from changing it.

contain a wrong unit specification, per discussion.
In passing, fix the code to avoid unnecessary integer overflows when
converting units, and to detect overflows when they do occur.

actually works sanely, viz not 0 and not more than INT_MAX/1000
(else TimestampTzPlusMilliseconds can overflow).  Per discussion with
Greg Stark.  Since this is a superuser-only setting and there was not
previously any big reason to change it, not worth back-patching.

within a signal handler (this might be safe given the relatively narrow code
range in which the interrupt is enabled, but it seems awfully risky); do issue
more informative log messages that tell what is being waited for and the exact
length of the wait; minor other code cleanup.  Greg Stark and Tom Lane

Simon Riggs

when multiple backends are scanning the same relation concurrently, each page
is (ideally) read only once.

Jeff Davis, with review by Heikki and Tom.