This is related to aa90e148, but this
code is only used under -DLINUX_OOM_ADJ, so it was apparently
overlooked then.

Use SvREFCNT_inc_simple_void() instead of SvREFCNT_inc() to avoid
warning about unused return value.

pg_catalog schema, even though they are not explicitly dumped (they are
implicitly dumped, e.g. create language plperl).

Avoids the need for an external script in the most common
scenario. Behavior can be overridden using the -n/--noloop
commandline parameter.

Write the file to a temporary name and then rename() it into the
permanent name, to ensure it can't end up half-written and corrupt
in case of a crash during shutdown.

Unlink the file after it has been read so it's removed from the data
directory and not included in base backups going to replication slaves.

The only interesting-for-performance case wherein we force heapscan here
is when we're rebuilding the relcache init file, and the only such case
that is likely to be examining a catalog big enough to be syncscanned is
RelationBuildTupleDesc.  But the early-exit optimization in that code gets
broken if we start the scan at a random place within the catalog, so that
allowing syncscan is actually a big deoptimization if pg_attribute is large
(at least for the normal case where the rows for core system catalogs have
never been changed since initdb).  Hence, prevent syncscan here.  Per my
testing pursuant to complaints from Jeff Frost and Greg Sabino Mullane,
though neither of them seem to have actually hit this specific problem.

Back-patch to 8.3, where syncscan was introduced.

Previously, casts to name could generate invalidly-encoded results.

Also, make these functions match namein() more exactly, by consistently
using palloc0() instead of ad-hoc zeroing code.

Back-patch to all supported branches.

Karl Schnaitter and Tom Lane

The previous coding presented a significant bottleneck when dumping
databases containing many thousands of schemas, since the total time
spent searching would increase roughly as O(N^2) in the number of objects.
Noted by Jeff Janes, though I rewrote his proposed patch to use the
existing findObjectByOid infrastructure.

Since this is a longstanding performance bug, backpatch to all supported
versions.

When backing up from a standby server, the backup process
will not automatically switch xlog segment. So we must
accept a partially transferred xlog file in this case, but
rename it into position anyway.

In passing, merge the two callbacks for segment end and
stop stream into a single callback, since their implementations
were close to identical, and rename this callback to
reflect that it stops streaming rather than continues it.

Patch by Magnus Hagander, review by Fujii Masao

start/stop output, to fix file share error reported by Edmund Horner

document fix of double counting and read/write count addition, per Peter
Geoghegan

Geoghegan

zaptreesubs() was coded to unconditionally reset a capture subre's
corresponding pmatch[] entry.  However, in regexes without backrefs, that
array is caller-supplied and might not have as many entries as the regex
has capturing parens.  So check the array length and do nothing if there
is no corresponding entry, much as subset() does.  Failure to check this
resulted in a stack clobber in the case reported by Marko Kreen.

This bug appears to have been latent in the regex library from the
beginning.  It was not exposed because find() called dissect() not
cdissect(), and the dissect() code path didn't ever call zaptreesubs()
(formerly zapmem()).  When I unified dissect() and cdissect() in commit
4dd78bf3, the problem was exposed.

Now that I've seen this, I'm rather suspicious that we might need to
back-patch it; but will refrain for now, for lack of evidence that
the case can be hit in the previous coding.

For space reasons, drop SQL:1999 and SQL:2003.  Only keep the latest
two and SQL-92 for historical comparison.

Windows, to avoid opening a file by multiple processes.

Fujii Masao

And align a bit better with the rest of the debug output.

Korotkov, per Alexander Korotkov.

If a seqscan encounters many consecutive pages containing only dead tuples,
it can remain in the loop in heapgettup for a long time, and there was no
CHECK_FOR_INTERRUPTS anywhere in that loop.  This meant there were
real-world situations where a query would be effectively uncancelable for
long stretches.  Add a check placed to occur once per page, which should be
enough to provide reasonable response time without adding any measurable
overhead.

Report and patch by Merlin Moncure (though I tweaked it a bit).
Back-patch to all supported branches.

Every time I read this I had doubts about whether the argument to the
-x option should include the dot (yes).  A small example should
clarify this.

reindexed, not vacuumed (typo).  Per report from Thomas REISS

types, per Alexander Korotkov

When the column name is an unqualified name, rather than table.column,
the error message complains about too many dotted names, which is
wrong.  Report by Peter Eisentraut based on examination of the
sepgsql regression test output, but the problem also affects COMMENT.
New wording as suggested by Tom Lane.

Document some more things as incompatibilities, and improve wording of
another item.

Noah Misch

Magnus Hagander, reviewed by Fujii Masao, with slight wording changes
by me.

In commit d526575f, we changed things so
that buffer usage counts are incremented when the buffer is pinned, rather
than when it is unpinned, but the README file didn't get the memo.

Report by Amit Kapila.

There is no reason to do this as early as possible in postmaster startup,
and good reason not to do it until we have completely created the
postmaster's lock file, namely that it might contribute to pg_ctl thinking
that postmaster startup has timed out.  (This would require a rather
unusual amount of time to be spent scanning temp file directories, but we
have at least one field report of it happening reproducibly.)

Back-patch to 9.1.  Before that, pg_ctl didn't wait for additional info to
be added to the lock file, so it wasn't a problem.

Note that this is not a complete fix to the slow-start issue in 9.1,
because we still had identify_system_timezone being run during postmaster
start in 9.1.  But that's at least a reasonably well-defined delay, with
an easy workaround if needed, whereas the temp-files scan is not so
predictable and cannot be avoided.

The accurate info about what's in a lock file has been in miscadmin.h
for some time, so let's just make this comment point there instead of
maintaining a duplicative copy.

The list was neither logical nor numerical nor alphabetical.  Let's go
with alphabetical.

For the record, fe-print.c is also missing, but it's sort of
deprecated, and the string internationalization there has some issues,
and it doesn't seem worth fixing that.  So let's leave that out.

Josh Kupershmidt

Per discussion, we should explain that we follow RFC 3339 and not really
the letter of the ISO 8601 spec for timestamp output format.  Mostly
Brendan Jurd's wording, though I tweaked it to clarify that we do take 'T'
on input.  Minor additional copy-editing and markup-tweaking, too.