* Refactor explain.c slightly to export a convenient-to-use subroutine
for printing EXPLAIN results.

* Provide hooks for plugins to get control at ExecutorStart and ExecutorEnd
as well as ExecutorRun.

* Add some minimal support for tracking the total runtime of ExecutorRun.
This code won't actually do anything unless a plugin prods it to.

* Change the API of the DefineCustomXXXVariable functions to allow nonzero
"flags" to be specified for a custom GUC variable.  While at it, also make
the "bootstrap" default value for custom GUCs be explicitly specified as a
parameter to these functions.  This is to eliminate confusion over where the
default comes from, as has been expressed in the past by some users of the
custom-variable facility.

* Refactor GUC code a bit to ensure that a custom variable gets initialized to
something valid (like its default value) even if the placeholder value was
invalid.

Andrew Chernow

getpeerucred() function.

Author: Garick Hamlin <ghamlin@isc.upenn.edu>

conflict resolution.

Performance is increased from 50% up to 10^3 times depending on data.

locate the target row, if the cursor was declared with FOR UPDATE or FOR
SHARE.  This approach is more flexible and reliable than digging through the
plan tree; for instance it can cope with join cursors.  But we still provide
the old code for use with non-FOR-UPDATE cursors.  Per gripe from Robert Haas.

also backpatched to 8.3

return the tableoid as well as the ctid for any FOR UPDATE targets that
have child tables.  All child tables are listed in the ExecRowMark list,
but the executor just skips the ones that didn't produce the current row.

Curiously, this longstanding restriction doesn't seem to have been documented
anywhere; so no doc changes.

procedure support: it's possible to get confused because exported procedures
have two different addresses.  Per Andrew Chernow.

since it's now just a SQL module and no C code.

This continues the saga of trying to get PGDLLIMPORT to work in pg_crc.h
in both backend and frontend environments.

array_agg() and unnest().  We could drop it entirely in the future,
but let's keep it for a release or two as a compatibility assist.

if the user is superuser.  This makes available to extension modules the same
sort of trick being practiced by array_agg().  The reason for the superuser
restriction is that you could crash the system by connecting up an
incompatible pair of internal-using functions as an aggregate.  It shouldn't
interfere with any legitimate use, since you'd have to be superuser to create
the internal-using transition and final functions anyway.

returns VOID.  This is the last of the easy fixes I recommended in
11870.1218838360@sss.pgh.pa.us --- the others got done awhile ago but
I forgot about this one.

before passing it to elog.

entries, we don't have to do two builds here as well.

another section if required by the platform (instead of the old way of
building them in section "l" and always transforming them to the
platform-specific section).

This speeds up the installation on common platforms, and it avoids some
funny business with the man page tools and build process.

a pointer, why don't we just fix that.  Every known use of "internal" really
means a pointer anyway.

heap_form_tuple.  Since this removes the last remaining caller of
heap_addheader, remove it.

Extracted from the column privileges patch from Stephen Frost, with further
code cleanups by me.

anyelement.  This lacks the WITH ORDINALITY option, as well as the multiple
input arrays option added in the most recent SQL specs.  But it's still a
pretty useful subset of the spec's functionality, and it is enough to
allow obsoleting contrib/intagg.

about how this is playing fast and loose with the type system.

and thereby in the pg_timezone_names view.  Although we allow such zones
to be used in certain limited contexts like AT TIME ZONE, we don't allow
them in SET TIME ZONE, and bug #4528 shows that they're more likely to
confuse users than do anything useful.  So hide 'em.  (Note that we don't
even generate these zones when installing our own timezone database.
But they are likely to be present when using a system-provided database.)

for inserting tuples in increasing TID order.  It's not clear whether this
fully explains Ivan Sergio Borgonovo's complaint, but simple testing
confirms that a scan that doesn't start at block 0 can slow GIN build by
a factor of three or four.

Backpatch to 8.3.  Sync scan didn't exist before that.

Rearrange the documentation a bit now that array_agg and xmlagg have similar
semantics and issues.

best of Robert Haas, Jeff Davis, Peter Eisentraut

I think this will fix current mingw buildfarm failures for pg_trgm.

Updated parser file to the one generated by the latest version of parse.[awk|pl] from the latest version of gram.y
Some small corrections to test suite.

- FloatOnly: only used by NumericOnly, instead put the FloatOnly production into NumericOnly
- IntegerOnly: only used by NumericOnly and one ALTER TABLE rule, replacement SignedIconst is already used in several other places

Add config parameter "sslverify" to control the verification. Default
is to do full verification.

Clean up some old SSL code that never really worked.

operator.  The result depends only on the two input operators and the proof
direction (imply or refute), so it's easy to cache.  This provides a very
large savings in cases such as Sergey Konoplev's long NOT-IN-list example,
where predtest spends all its time repeatedly figuring out that the same pair
of operators cannot be used to prove anything.  (But of course the O(N^2)
behavior still catches up with you eventually.)  I'm not convinced it buys
a whole lot when constraint_exclusion isn't turned on, but it's not a lot
of added code so we might as well cache all the time.

AND, OR, or equivalent clauses: if there are too many (more than 100) just
exit without proving anything.  This ensures that we don't spend O(N^2) time
trying (and most likely failing) to prove anything about very long IN lists
and similar cases.

Also, install a couple of CHECK_FOR_INTERRUPTS calls to ensure that a long
proof attempt can be interrupted.

Per gripe from Sergey Konoplev.

Back-patch the whole patch to 8.2 and just the CHECK_FOR_INTERRUPTS addition
to 8.1.  (The rest of the patch doesn't apply cleanly, and since 8.1 doesn't
show the complained-of behavior anyway, it doesn't seem necessary to work
hard on it.)