In preparation for 9.1alpha4 release notes, where only the 9.1alpha4
features will be emphasized.

Recommend use of CREATE EXTENSION rather than plain CREATE LANGUAGE
where relevant.  Encourage PL authors to provide extension wrappers
for their PLs.

This mostly just involves creating control, install, and
update-from-unpackaged scripts for them.  However, I had to adjust plperl
and plpython to not share the same support functions between variants,
because we can't put the same function into multiple extensions.

catversion bump forced due to new contents of pg_pltemplate, and because
initdb now installs plpgsql as an extension not a bare language.

Add support for regression testing these as extensions not bare
languages.

Fix a couple of other issues that popped up while testing this: my initial
hack at pg_dump binary-upgrade support didn't work right, and we don't want
an extra schema permissions test after all.

Documentation changes still to come, but I'm committing now to see
whether the MSVC build scripts need work (likely they do).

This avoids duplicate (and not-quite-matching) code, and makes the logic
for SECURITY LABEL match COMMENT and ALTER EXTENSION ADD/DROP.

It is possible that an expression ends up with a collatable type but
without a collation.  CREATE TABLE AS could then create a table based
on that.  But such a column cannot be dumped with valid SQL syntax, so
we disallow creating such a column.

per test report from Noah Misch

Remove the unconditional superuser permissions check in CREATE EXTENSION,
and instead define a "superuser" extension property, which when false
(not the default) skips the superuser permissions check.  In this case
the calling user only needs enough permissions to execute the commands
in the extension's installation script.  The superuser property is also
enforced in the same way for ALTER EXTENSION UPDATE cases.

In other ALTER EXTENSION cases and DROP EXTENSION, test ownership of
the extension rather than superuserness.  ALTER EXTENSION ADD/DROP needs
to insist on ownership of the target object as well; to do that without
duplicating code, refactor comment.c's big switch for permissions checks
into a separate function in objectaddress.c.

I also removed the superuserness checks in pg_available_extensions and
related functions; there's no strong reason why everybody shouldn't
be able to see that info.

Also invent an IF NOT EXISTS variant of CREATE EXTENSION, and use that
in pg_dump, so that dumps won't fail for installed-by-default extensions.
We don't have any of those yet, but we will soon.

This is all per discussion of wrapping the standard procedural languages
into extensions.  I'll make those changes in a separate commit; this is
just putting the core infrastructure in place.

This is the same check that would happen later when the collation is
used, but it's friendlier to check the collation already when it is
created.

Instead, just act as though the certificate file(s) are not present.
There is only one case where this need be a hard failure condition: when
sslmode is verify-ca or verify-full, not having a root cert file is an
error.  Change the logic so that we complain only in that case, and
otherwise fall through cleanly.  This is how it used to behave pre-9.0,
but my patch 4ed4b6c5 of 2010-05-26 broke
the case.  Per report from Christian Kastner.

CheckForSerializableConflictOut(), because it can set hint bits.

YAMAMOTO Takashi

Mostly text supplied by Jan Urbański.

Instead of manually maintaining the "implementation of XXX operator"
comments in pg_proc.h, delete all those entries and let initdb create
them via a join.  To let initdb figure out which name to use when there
is a conflict, change the comments for deprecated operators to say they
are deprecated --- which seems like a good thing to do anyway.

Although there remains some debate about how CREATE TYPE should represent
the collation property, this doesn't really affect what we need to do in
citext's script, so go ahead and fix that.

This works around the problem noted by Yamamoto Takashi in bug #5906,
that there were code paths whereby we could reach AtCleanup_Portals
with a portal's cleanup hook still unexecuted.  The changes I made
a few days ago were intended to prevent that from happening, and
I think that on balance it's still a good thing to avoid, so I don't
want to remove the Assert in AtCleanup_Portals.  Hence do this instead.

Andy Colson <andy@squeakycode.net>.

Andrey Popp

Now that btree_gist contains a reference to isinf(), this is necessary
at least on some platforms.  Per buildfarm.

Historically, we've not had separate comments for built-in pg_operator
entries, but relied on the comments for the underlying functions.  The
trouble with this approach is that there isn't much of anything to suggest
to users that they'd be better off using the operators instead.  So, move
all the relevant comments into pg_operator, and give each underlying
function a comment that just says "implementation of XXX operator".
There are only about half a dozen cases where it seems reasonable to use
the underlying function interchangeably with the operator; in these cases
I left the same comment in place on the function as on the operator.

While at it, establish a policy that every built-in function and operator
entry should have a comment: there are now queries in the opr_sanity
regression test that will complain if one doesn't.  This only required
adding a dozen or two more entries than would have been there anyway.

I also spent some time trying to eliminate gratuitous inconsistencies in
the style of the comments, though it's hopeless to suppose that more won't
creep in soon enough.

Per my proposal of 2010-10-15.

This is faked information like for domains.

This extends GiST's support for nearest-neighbor searches to many of the
standard data types.

Teodor Sigaev

Mapped to NetBSD, the closest existing match.  (Even though DragonFly
BSD is derived from FreeBSD, the shared library version numbering
matches NetBSD, and the rest is mostly the same among all BSD
variants.)

per "Rumko"

The grammar requires a specific ordering of the clauses, but the
documentation showed a different order.  This error was introduced in
commit b47953f9, which merged the CREATE
CONSTRAINT TRIGGER documentation into the CREATE TRIGGER page.  There is
no code bug AFAICS.

Time spent executing AFTER triggers is not included in the runtime of the
associated ModifyTable node; in my patch of yesterday I confused queuing of
these triggers with their actual execution.  Spotted by Marko Tiikkaja.

Patch from Jan Urbański.

plpython_subtransaction test needs a separate expected file
specifically for Python 2.5.

it a lot more useful for determining which standby is most up-to-date,
for example. There was long discussions on whether overwriting existing
existing WAL makes sense to begin with, and whether we should do some more
extensive variable renaming, but this change nevertheless seems quite
uncontroversial.

Fujii Masao, reviewed by Jeff Janes, Robert Haas, Stephen Frost.

Change the way UPDATEs are handled. Instead of maintaining a chain of
tuple-level locks in shared memory, copy any existing locks on the old
tuple to the new tuple at UPDATE. Any existing page-level lock needs to
be duplicated too, as a lock on the new tuple. That was neglected
previously.

Store xmin on tuple-level predicate locks, to distinguish a lock on an old
already-recycled tuple from a new tuple at the same physical location.
Failure to distinguish them caused loops in the tuple-lock chains, as
reported by YAMAMOTO Takashi. Although we don't use the chain representation
of UPDATEs anymore, it seems like a good idea to store the xmin to avoid
some false positives if no other reason.

CheckSingleTargetForConflictsIn now correctly handles the case where a lock
that's being held is not reflected in the local lock table. That happens
if another backend acquires a lock on our behalf due to an UPDATE or a page
split.

PredicateLockPageCombine now retains locks for the page that is being
removed, rather than removing them. This prevents a potentially dangerous
false-positive inconsistency where the local lock table believes that a lock
is held, but it is actually not.

Dan Ports and Kevin Grittner

This was previously omitted by accident.

Back-patch to 9.0, since this was changed then.

Per discussion, this seems important for plans involving writable CTEs,
since there can now be more than one ModifyTable node in the plan.

To retain the same formatting as for target tables of scan nodes, we
show only one target table, which will be the parent table in case of
an UPDATE or DELETE on an inheritance tree.  Individual child tables
can be determined by inspecting the child plan trees if needed.

Without this patch, when wal_receiver_status_interval=0, indicating that no
status messages should be sent, Hot Standby feedback messages are instead sent
extremely frequently.

Fujii Masao, with documentation changes by me.

With this patch, portals, SQL functions, and SPI all agree that there
should be only a CommandCounterIncrement between the queries that are
generated from a single SQL command by rule expansion.  Fetching a whole
new snapshot now happens only between original queries.  This is equivalent
to the existing behavior of EXPLAIN ANALYZE, and it was judged to be the
best choice since it eliminates one source of concurrency hazards for
rules.  The patch should also make things marginally faster by reducing the
number of snapshot push/pop operations.

The patch removes pg_parse_and_rewrite(), which is no longer used anywhere.
There was considerable discussion about more aggressive refactoring of the
query-processing functions exported by postgres.c, but for the moment
nothing more has been done there.

I also took the opportunity to refactor snapmgr.c's API slightly: the
former PushUpdatedSnapshot() has been split into two functions.

Marko Tiikkaja, reviewed by Steve Singer and Tom Lane

For consistency with pg_last_xlog_replay_location.  Per discussion.

This provides a separate exception class for each error code that the
backend defines, as well as the ability to get the SQLSTATE from the
exception object.

Jan Urbański, reviewed by Steve Singer

Marko Tiikkaja, somewhat reworked by Tom

Adds a context manager, obtainable by plpy.subtransaction(), to run a
group of statements in a subtransaction.

Jan Urbański, reviewed by Steve Singer, additional scribbling by me

We don't have complete expected coverage for Python 2.2 anyway, so it
doesn't seem worth keeping this one around that no one appears to be
updating anyway.  Visual inspection of the differences ought to be
good enough for those few who care about this obsolete Python version.