In the previous coding, a user could queue up for an AccessExclusiveLock
on a table they did not have permission to cluster, thus potentially
interfering with access by authorized users who got stuck waiting behind
the AccessExclusiveLock.  This approach avoids that.  cluster() has the
same permissions-checking requirements as REINDEX TABLE, so this commit
moves the now-shared callback to tablecmds.c and renames it, per
discussion with Noah Misch.

When a PORTAL_ONE_SELECT query is executed, we can opportunistically
reuse the parse/plan shot for the execution phase.  This cuts down the
number of snapshots per simple query from 2 to 1 for the simple
protocol, and 3 to 2 for the extended protocol.  Since we are only
reusing a snapshot taken early in the processing of the same protocol
message, the change shouldn't be user-visible, except that the remote
possibility of the planning and execution snapshots being different is
eliminated.

Note that this change does not make it safe to assume that the parse/plan
snapshot will certainly be reused; that will currently only happen if
PortalStart() decides to use the PORTAL_ONE_SELECT strategy.  It might
be worth trying to provide some stronger guarantees here in the future,
but for now we don't.

Patch by me; review by Dimitri Fontaine.

KaiGai Kohei, reviewed by Dimitri Fontaine and me.

Pavel Stehule

The original coding of this function overlooked the possibility that
it could be passed anything except simple OpExpr indexquals.  But
ScalarArrayOpExpr is possible too, and the code would probably crash
(and surely give ridiculous answers) in such a case.  Add logic to try
to estimate sanely for such cases.

In passing, fix the treatment of inner-indexscan cost estimation: it was
failing to scale up properly for multiple iterations of a nestloop.
(I think somebody might've thought that index_pages_fetched() is linear,
but of course it's not.)

Report, diagnosis, and preliminary patch by Marti Raudsepp; I refactored
it a bit and fixed the cost estimation.

Back-patch into 9.1 where the bogus code was introduced.

smgrdounlink takes care to not throw an ERROR if it fails to unlink
something, but that caution was rendered useless by commit
33960006, which put an smgrexists call in
front of it; smgrexists *does* throw error if anything looks funny, such
as getting a permissions error from trying to open the file.  If that
happens post-commit, you get a PANIC, and what's worse the same logic
appears in the WAL replay code, so the database even fails to restart.

Restore the intended behavior by removing the smgrexists call --- it isn't
accomplishing anything that we can't do better by adjusting mdunlink's
ideas of whether it ought to warn about ENOENT or not.

Per report from Joseph Shraibman of unrecoverable crash after trying to
drop a table whose FSM fork had somehow gotten chmod'd to 000 permissions.
Backpatch to 8.4, where the bogus coding was introduced.

This adds support for the more or less SQL-conforming USAGE privilege
on types and domains.  The intent is to be able restrict which users
can create dependencies on types, which restricts the way in which
owners can alter types.

reviewed by Yeb Havinga

Per Tom

On reflection, the original name seems way too generic for a global
symbol.  A quick check shows this is the only exported function name
in SP-GiST that doesn't begin with "spg" or contain "SpGist", so the
rest of them seem all right.

This makes them enforceable only on the parent table, not on children
tables.  This is useful in various situations, per discussion involving
people bitten by the restrictive behavior introduced in 8.4.

Message-Id:
8762mp93iw.fsf@comcast.net
CAFaPBrSMMpubkGf4zcRL_YL-AERUbYF_-ZNNYfb3CVwwEqc9TQ@mail.gmail.com

Authors: Nikhil Sontakke, Alex Hunsaker
Reviewed by Robert Haas and myself

Operator classes can specify whether or not they support this; this
preserves the flexibility to use lossy representations within an index.

In passing, move constant data about a given index into the rd_amcache
cache area, instead of doing fresh lookups each time we start an index
operation.  This is mainly to try to make sure that spgcanreturn() has
insignificant cost; I still don't have any proof that it matters for
actual index accesses.  Also, get rid of useless copying of FmgrInfo
pointers; we can perfectly well use the relcache's versions in-place.

The need for this was debated when we put in the index-only-scan feature,
but at the time we had no near-term expectation of having AMs that could
support such scans for only some indexes; so we kept it simple.  However,
the SP-GiST AM forces the issue, so let's fix it.

This patch only installs the new API; no behavior actually changes.

This moves the code around from one huge file into hopefully logical
and more manageable modules.  For the most part, the code itself was
not touched, except: PLy_function_handler and PLy_trigger_handler were
renamed to PLy_exec_function and PLy_exec_trigger, because they were
not actually handlers in the PL handler sense, and it makes the naming
more similar to the way PL/pgSQL is organized.  The initialization of
the procedure caches was separated into a new function
init_procedure_caches to keep the hash tables private to
plpy_procedures.c.

Jan Urbański and Peter Eisentraut

suite for ecpg.

Ever since we introduced real prepared statements this should work for
different connections. The old solution just emulating prepared statements,
though, wasn't able to handle this.

Closes: #6309

Should've thought of that one earlier.

These entries could never be matched to an index clause because they don't
have the index datatype on the left-hand side of the operator.  (Their
commutators are in the opclass, which is sensible, but that doesn't mean
these operators should be.)  Spotted by a test that I recently added to
opr_sanity to catch exactly this type of thinko.  AFAICT there is no code
in gistproc.c that is specifically meant to cover these cases, so nothing
to remove at that level.

These were missed in commit a213f1ee,
which removed that function.

SP-GiST is comparable to GiST in flexibility, but supports non-balanced
partitioned search structures rather than balanced trees.  As described at
PGCon 2011, this new indexing structure can beat GiST in both index build
time and query speed for search problems that it is well matched to.

There are a number of areas that could still use improvement, but at this
point the code seems committable.

Teodor Sigaev and Oleg Bartunov, with considerable revisions by Tom Lane

Per gripe from Thom Brown.

Heikki Linnakangas had the idea of rearranging GetSnapshotData to
avoid checking for sub-XIDs when no top-level XID is present.  This
patch does that plus further a bit of further, related rearrangement.
Benchmarking show a significant improvement on unlogged tables at
higher concurrency levels, and mostly indifferent result on permanent
tables (which are presumably bottlenecked elsewhere).  Most of the
benefit seems to come from using the new NormalTransactionIdPrecedes()
macro rather than the function call TransactionIdPrecedes().

Valid values are --pre-data, data and post-data. The option can be
given more than once. --schema-only is equivalent to
--section=pre-data --section=post-data. --data-only is equivalent
to --section=data.

Andrew Dunstan, reviewed by Joachim Wieland and Josh Berkus.

This works the same as include, except that an error is not thrown
if the file is missing. Instead the fact that it's missing is
logged.

Greg Smith, reviewed by Euler Taveira de Oliveira.

If the referrent of a name changes while we're waiting for the lock,
we must recheck permissons.  We also now check the relkind before
locking, since it's easy to do that long the way.

Patch by me; review by Noah Misch.

Previously, renaming a table, sequence, view, index, foreign table,
column, or trigger checked permissions before locking the object, which
meant that if permissions were revoked during the lock wait, we would
still allow the operation.  Similarly, if the original object is dropped
and a new one with the same name is created, the operation will be allowed
if we had permissions on the old object; the permissions on the new
object don't matter.  All this is now fixed.

Along the way, attempting to rename a trigger on a foreign table now gives
the same error message as trying to create one there in the first place
(i.e. that it's not a table or view) rather than simply stating that no
trigger by that name exists.

Patch by me; review by Noah Misch.

Fixes an oversight in commit fc6d1006.

Noted by Tom Lane.

Lots of repetitive code was moved into new functions
PLy_spi_subtransaction_{begin,commit,abort}.

Jan Urbański

Suggested solution from Tom Lane. Problem discovered, probably not
for the first time, while testing the mingw-w64 32 bit compiler.

Backpatched to all live branches.

Andrew Dunstan, reviewed by Josh Berkus, Robert Haas and Peter Geoghegan.

This allows dumping of a table definition but not its data, on a per table basis.
Table name patterns are supported just as for --exclude-table.

Yeb Havinga, reviewed by Kevin Grittner, with small changes by me.

Removing this bit from xl_info allows us to restore the old limit of four
(not three) separate pages touched by a WAL record, which is needed for the
upcoming SP-GiST feature, and will likely be useful elsewhere in future.

When we implemented XLR_BKP_REMOVABLE in 2007, we had to do it like that
because no special WAL-visible action was taken when starting a backup.
However, now we force a segment switch when starting a backup, so a
compressing WAL archiver (such as pglesslog) that uses the state shown in
the current page header will not be fooled as to removability of backup
blocks.  The only downside is that the archiver will not return to
compressing mode for up to one WAL page after the backup is over, which is
a small price to pay for getting back the extra xl_info bit.  In any case
the archiver could look for XLOG_BACKUP_END records if it thought it was
worth the trouble to do so.

Bump XLOG_PAGE_MAGIC since this is effectively a change in WAL format.