This method will not catch all different ways since the locale
handling in NTFS doesn't provide an easy way to do that, but it
will hopefully solve the most common cases causing startup
problems when the backend is found in the system PATH.

Attempts to fix bug #4694.

ineffective posix_fadvise().

for simple Var targetlist entries all the time, even when there are other
entries that are not simple Vars.  Also, ensure that we prefetch attributes
(with slot_getsomeattrs) for all Vars in the targetlist, even those buried
within expressions.  In combination these changes seem to significantly
reduce the runtime for cases where tlists are mostly but not exclusively
Vars.  Per my proposal of yesterday.

"effective_io_concurrency" on systems without posix_fadvise().

Andrew Gierth

Robert Lor

Per "maosen.zhang" <maosen.zhang@alibaba-inc.com> report.

specified.

Martin Pihlak

conversion functions.  This allows transaction rollback to revert to a
previous client_encoding setting without doing fresh catalog lookups.
I believe that this explains and fixes the recent report of "failed to commit
client_encoding" failures.

This bug is present in 8.3.x, but it doesn't seem prudent to back-patch
the fix, at least not till it's had some time for field testing in HEAD.

In passing, remove SetDefaultClientEncoding(), which was used nowhere.

we failed to assign, even in "can't happen" cases.  Motivated by wondering
what's going on in a recent trouble report where "failed to commit" did
happen.

casting effort whenever the input value was NULL.  However this prevents
application of not-null domain constraints in the cases that use this
function, as illustrated in bug #4741.  Since this function isn't meant
for use in performance-critical paths anyway, this certainly seems like
another case of "premature optimization is the root of all evil".

Back-patch as far as 8.2; older versions made no effort to enforce
domain constraints here anyway.

when there are many blobs and not so many comments.  Tamas Vincze

per-database settings.

temporary tables of other sessions; that is unsafe because of the way our
buffer management works.  Per report from Stuart Bishop.
This is redundant with the bufmgr.c checks in HEAD, but not at all redundant
in the back branches.

at the top of their sections.

temp relations; this is no more expensive than before, now that we have
pg_class.relistemp.  Insert tests into bufmgr.c to prevent attempting
to fetch pages from nonlocal temp relations.  This provides a low-level
defense against bugs-of-omission allowing temp pages to be loaded into shared
buffers, as in the contrib/pgstattuple problem reported by Stuart Bishop.
While at it, tweak a bunch of places to use new relcache tests (instead of
expensive probes into pg_namespace) to detect local or nonlocal temp tables.

Give an error message and exit instead, like we do elsewhere...

Per report from Wez Furlong and Robert Treat.

relations (including a temp table's indexes and toast table/index), and
false for normal relations.  For ease of checking, this commit just adds
the column and fills it correctly --- revising the relation access machinery
to use it will come separately.

at the same instant as a new backend is spawned. Since CountActiveBackends()
doesn't hold ProcArrayLock, it needs to be prepared for the case that a
pointer at the end of the proc array is still NULL even though numProcs says
it should be valid, since it doesn't hold ProcArrayLock. Backpatch to 8.1.
8.0 and earlier had this right, but it was broken in the split of PGPROC and
sinval shared memory arrays.

Per report and proposal by Marko Kreen.

but not OpenSSL (or perhaps vice versa, if that's possible).

Andrew Chernow, with minor editorialization by me.

(Not clear how useful these really are, but failing is no good...)
Per report from David Fetter and Robert Treat.

further backpatch.

TupleTableSlots.  We have functions for retrieving a minimal tuple from a slot
after storing a regular tuple in it, or vice versa; but these were implemented
by converting the internal storage from one format to the other.  The problem
with that is it invalidates any pass-by-reference Datums that were already
fetched from the slot, since they'll be pointing into the just-freed version
of the tuple.  The known problem cases involve fetching both a whole-row
variable and a pass-by-reference value from a slot that is fed from a
tuplestore or tuplesort object.  The added regression tests illustrate some
simple cases, but there may be other failure scenarios traceable to the same
bug.  Note that the added tests probably only fail on unpatched code if it's
built with --enable-cassert; otherwise the bug leads to fetching from freed
memory, which will not have been overwritten without additional conditions.

Fix by allowing a slot to contain both formats simultaneously; which turns out
not to complicate the logic much at all, if anything it seems less contorted
than before.

Back-patch to 8.2, where minimal tuples were introduced.

still more work to do.

from patch author:

       Add /contrib/citext as a case-insensitive, multibyte-capable
	text data type (David Wheeler)