Retry after buffer locking failure during SPGiST index creation.

The original coding thought this case was impossible, but it can happen
if the bgwriter or checkpointer processes decide to write out an index
page while creation is still proceeding, leading to a bogus "unexpected
spgdoinsert() failure" error.  Problem reported by Jonathan S. Katz.

Teodor Sigaev
Fix subquery reference to non-populated MV in CMV.

A subquery reference to a matview should be allowed by CREATE
MATERIALIZED VIEW WITH NO DATA, just like a direct reference is.

Per bug report from Laurent Sartran.

Backpatch to 9.3.
Acquire appropriate locks when rewriting during RMV.

Since the query has not been freshly parsed when executing REFRESH
MATERIALIZED VIEW, locks must be explicitly taken before rewrite.

Backpatch to 9.3.

Andres Freund
Changed test case slightly so it doesn't have an unused typedef.
Prevent memory leaks from accumulating across printtup() calls.

Historically, printtup() has assumed that it could prevent memory leakage
by pfree'ing the string result of each output function and manually
managing detoasting of toasted values.  This amounts to assuming that
datatype output functions never leak any memory internally; an assumption
we've already decided to be bogus elsewhere, for example in COPY OUT.
range_out in particular is known to leak multiple kilobytes per call, as
noted in bug #8573 from Godfried Vanluffelen.  While we could go in and fix
that leak, it wouldn't be very notationally convenient, and in any case
there have been and undoubtedly will again be other leaks in other output
functions.  So what seems like the best solution is to run the output
functions in a temporary memory context that can be reset after each row,
as we're doing in COPY OUT.  Some quick experimentation suggests this is
actually a tad faster than the retail pfree's anyway.

This patch fixes all the variants of printtup, except for debugtup()
which is used in standalone mode.  It doesn't seem worth worrying
about query-lifespan leaks in standalone mode, and fixing that case
would be a bit tedious since debugtup() doesn't currently have any
startup or shutdown functions.

While at it, remove manual detoast management from several other
output-function call sites that had copied it from printtup().  This
doesn't make a lot of difference right now, but in view of recent
discussions about supporting "non-flattened" Datums, we're going to
want that code gone eventually anyway.

Back-patch to 9.2 where range_out was introduced.  We might eventually
decide to back-patch this further, but in the absence of known major
leaks in older output functions, I'll refrain for now.
Get rid of more cases of the "must detoast before output function" meme.

I missed that json.c was doing this too, because for some bizarre reason
it wasn't doing it adjacent to the output function call.
Fix parsing of xlog file name in pg_receivexlog.

The parsing of WAL filenames of segments larger than > 255 was broken,
making pg_receivexlog unable to restart streaming after stopping it.

The bug was introduced by the changes in 9.3 to represent WAL segment number
as a 64-bit integer instead of two ints, log and seg. To fix, replace the
plain sscanf call with XLogFromFileName macro, which does the conversion
from log+seg to a 64-bit integer correcly.

Reported by Mika Eloranta.
Fix format code used to print dsm request sizes.

Per report from Peter Eisentraut.
Fix breakage of MV column name list usage.

Per bug report from Tomonari Katsumata.

Back-patch to 9.3.
Fix some obsolete information in src/backend/optimizer/README.

Constant quals aren't handled the same way they used to be.  Also,
add mention of a couple more major steps in grouping_planner.
Per complaint a couple months back from Etsuro Fujita.
Lock relation used to generate fresh data for RMV.

The relation should not be accessible to any other process, but it
should be locked for consistency.  Since this is not known to
cause any bug, it will not be back-patch, at least for now.

Per report from Andres Freund