This commit provides the core code and documentation needed.  A contrib
module test case will follow shortly.

Shigeru Hanada, Jan Urbanski, Heikki Linnakangas

avg() because it was inaccurate.

Marko Kreen

from information_schema.referential_constraints might return several in
Postgres because we allow duplicate-named constraints in the same
schema.

type changes.

The invalidation will cause the type information to be refetched, and
everything will work.

Jan Urbański, reviewed by Alex Hunsaker

Add a new libpq connection option client_encoding (which includes the
existing PGCLIENTENCODING environment variable), which besides an
encoding name accepts a special value "auto" that tries to determine
the encoding from the locale in the client's environment, using the
mechanisms that have been in use in initdb.

psql sets this new connection option to "auto" when running from a
terminal and not overridden by setting PGCLIENTENCODING.

original code by Heikki Linnakangas, with subsequent contributions by
Jaime Casanova, Peter Eisentraut, Stephen Frost, Ibrar Ahmed

Add a fdwhandler column to pg_foreign_data_wrapper, plus HANDLER options
in the CREATE FOREIGN DATA WRAPPER and ALTER FOREIGN DATA WRAPPER commands,
plus pg_dump support for same.  Also invent a new pseudotype fdw_handler
with properties similar to language_handler.

This is split out of the "FDW API" patch for ease of review; it's all stuff
we will certainly need, regardless of any other details of the FDW API.
FDW handler functions will not actually get called yet.

In passing, fix some omissions and infelicities in foreigncmds.c.

Shigeru Hanada, Jan Urbanski, Heikki Linnakangas

configuration rules.

Erik Rijkers

This has been broken for awhile, but not clear it's worth back-patching.

Euler Taveira de Oliveira

The previous coding would try to process all SECTION_NONE items in the
initial sequential-restore pass, which failed if they were dependencies of
not-yet-restored items.  Fix by postponing such items into the parallel
processing pass once we have skipped any non-PRE_DATA item.

Back-patch into 9.0; the original parallel-restore coding in 8.4 did not
have this bug, so no need to change it.

Report and diagnosis by Arnd Hannemann.

intarray and tsearch2 both reference core support functions in their GIN
opclasses, and the signatures of those functions changed for 9.1.  We added
backwards-compatible pg_proc entries for the functions in order to allow
9.0 dump files to be restored at all, but that hack leaves the opclasses
pointing at pg_proc entries different from what they'd point to if the
contrib modules were installed fresh in 9.1.  To forestall any possibility
of future problems, fix the opclasses to match fresh installs via the
expedient of direct UPDATEs on pg_amproc in the update-from-unpackaged
scripts.  (Yech ... but the alternatives are worse, or require far more
effort than seems justified right now.)

Note: updating pg_amproc is sufficient because there will be no pg_depend
entries corresponding to these dependencies, since the referenced functions
are all pinned.

Per discussion after my commit o yesterday.

More useful state change for monitoring purposes, plus a
required change for synchronous replication patch.

Allow messages to be sent at different times, and greatly reduce
the frequency of hot standby feedback. Refactor to allow additional
message types.

Kevin Grittner

Applied a patch by Zoltán Böszörményi that makes ecpg's parser accept dynamic cursornames even in WHERE CURRENT OF clauses.

Shigeru HANADA

They share the same locking namespace with the existing session-level
advisory locks, but they are automatically released at the end of the
current transaction and cannot be released explicitly via unlock
functions.

Marko Tiikkaja, reviewed by me.

More generally, arrays are turned in Perl array references, and row and
composite types are turned into Perl hash references.  This is done
recursively, in a way that's natural to every Perl programmer.

To avoid a backwards compatibility hit, the string representation of
each structure is also available if the function requests it.

Authors: Alexey Klyukin and Alex Hunsaker.
Some code cleanups by me.

This allows the user to change the path to be used more easily.
Also, change URL in README.

ts_typanalyze.c computes MCE statistics as fractions of the non-null rows,
which seems fairly reasonable, and anyway changing it in released versions
wouldn't be a good idea.  But then ts_selfuncs.c has to account for that.
Failure to do so results in overestimates in columns with a significant
fraction of null documents.  Back-patch to 8.4 where this stuff was
introduced.

Jesper Krogh

Update script was being sloppy about two functions that have been changed
since 9.0.

Take care of a couple of discrepancies between what you get from a fresh
install and what the first-draft update-from-unpackaged scripts produced.

The initial version of the update-from-unpackaged script neglected to
include the <> operators that were added to the opclasses during 9.1.
To make this script produce the same final state as the regular install
script, use the same ALTER OPERATOR FAMILY trick as in pg_trgm.

Peter Eisentraut, reviewed by Steve Singer, Alvaro Herrera, and me.

Simon Riggs reports that rnode.dbNode and rnode.spcNode were
generating unused variable warnings on gcc 4.4.3 with CFLAGS=-O1

Erik Rijkers

Take care of some loose ends in the update-from-unpackaged script, and
apply some ugly hacks to ensure that it produces the same catalog state
as the fresh-install script.  Per discussion, this seems like a safer
plan than having two different catalog states that both call themselves
"pg_trgm 1.0", even if it's not immediately clear that the subtle
differences would ever matter.

Also, fix the stub function gin_extract_trgm() so that it works instead
of just bleating.  Needed because this function will get called during a
regular dump and reload, if there are any indexes using its opclass.
The user won't have an opportunity to update the extension till later,
so telling him to do so is unhelpful.

unique exception, or if not used in read committed transaction mode.

because concat() is a built-in function.

Erik Rijkers

Stephen Frost, somewhat rewritten by me

Thom Brown

Instead, document how to build it manually.

Per discussion.  KaiGai Kohei, with some wordsmithing by me.

Doesn't anybody around here pay attention to compiler warnings?

That function was supposing that indexoid == 0 for a hypothetical index,
but that is not likely to be true in any non-toy implementation of an index
adviser, since assigning a fake OID is the only way to know at EXPLAIN time
which hypothetical index got selected.  Fix by adding a flag to
IndexOptInfo to mark hypothetical indexes.  Back-patch to 9.0 where
get_actual_variable_range() was added.

Gurjeet Singh

These are needed to support reloading dumps of 9.0 installations containing
contrib/intarray or contrib/tsearch2.  Since not only regular dump/reload
but binary upgrade would fail, it seems worth the trouble to carry these
stubs for awhile.  Note that the contrib opclasses referencing these
functions will still work fine, since GIN doesn't actually pay any
attention to the declared signature of a support function.