per recent discussions.  In passing this also fixes a couple of bugs in
the previous variadic-parameters patch.

to return NULL, instead of erroring out, if the target object is specified by
OID and we can't find that OID in the catalogs.  Since these functions operate
internally on SnapshotNow rules, there is a race condition when using them
in user queries: the query's MVCC snapshot might "see" a catalog row that's
already committed dead, leading to a failure when the inquiry function is
applied.  Returning NULL should generally provide more convenient behavior.
This issue has been complained of before, and in particular we are now seeing
it in the regression tests due to another recent patch.

Pavel Stehule, with some tweaks by Peter Eisentraut

heap page, where a set bit indicates that all tuples on the page are
visible to all transactions, and the page therefore doesn't need
vacuuming. It is stored in a new relation fork.

Lazy vacuum uses the visibility map to skip pages that don't need
vacuuming. Vacuum is also responsible for setting the bits in the map.
In the future, this can hopefully be used to implement index-only-scans,
but we can't currently guarantee that the visibility map is always 100%
up-to-date.

In addition to the visibility map, there's a new PD_ALL_VISIBLE flag on
each heap page, also indicating that all tuples on the page are visible to
all transactions. It's important that this flag is kept up-to-date. It
is also used to skip visibility tests in sequential scans, which gives a
small performance gain on seqscans.

to drop a table that is referenced by an open cursor.  Fix unstable
ecpg regression test result that was produced by this oversight.

business in core.

truncations in FSM code, call FreeSpaceMapTruncateRel from smgr_redo. To
make that cleaner from modularity point of view, move the WAL-logging one
level up to RelationTruncate, and move RelationTruncate and all the
related WAL-logging to new src/backend/catalog/storage.c file. Introduce
new RelationCreateStorage and RelationDropStorage functions that are used
instead of calling smgrcreate/smgrscheduleunlink directly. Move the
pending rel deletion stuff from smgrcreate/smgrscheduleunlink to the new
functions. This leaves smgr.c as a thin wrapper around md.c; all the
transactional stuff is now in storage.c.

This will make it easier to add new forks with similar truncation logic,
like the visibility map.

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.

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.

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

("there might be triggers") rather than an exact count.  This is necessary
catalog infrastructure for the upcoming patch to reduce the strength of
locking needed for trigger addition/removal.  Split out and committed
separately for ease of reviewing/testing.

In passing, also get rid of the unused pg_class columns relukeys, relfkeys,
and relrefs, which haven't been maintained in many years and now have no
chance of ever being maintained (because of wishing to avoid locking).

Simon Riggs

and heap_deformtuple in favor of the newer functions heap_form_tuple et al
(which do the same things but use bool control flags instead of arbitrary
char values).  Eliminate the former duplicate coding of these functions,
reducing the deprecated functions to mere wrappers around the newer ones.
We can't get rid of them entirely because add-on modules probably still
contain many instances of the old coding style.

Kris Jurka

Also, since WITH is now a reserved word, simplify the token merging code to
only deal with WITH_TIME.

by Tom Lane and myself

(INCLUDING/EXCLUDING DEFAULTS)

OFFSET num {ROW|ROWS} FETCH {FIRST|NEXT} [num] {ROW|ROWS} ONLY

alongside our traditional syntax.

dropped or it was a mistake.

supported, to the extent that LOBs, arrays, and multisets are supported.

lengthof(SysAtt) not FirstLowInvalidHeapAttributeNumber, for consistency with
the other uses of the SysAtt array, and to make it clearer that it doesn't
walk off the end of that array.

Formerly, the lack of any opclasses that could accept such data was enough
of a defense, but now with a "record" opclass we need to check more carefully.
(You can still use that opclass for an index, but you have to store a named
composite type not an anonymous one.)

relation forks. While the file names are not visible to users, for those
that do peek into the data directory, it's nice to have more descriptive
names. Per Greg Stark's suggestion.

There are some unimplemented aspects: recursive queries must use UNION ALL
(should allow UNION too), and we don't have SEARCH or CYCLE clauses.
These might or might not get done for 8.4, but even without them it's a
pretty useful feature.

There are also a couple of small loose ends and definitional quibbles,
which I'll send a memo about to pgsql-hackers shortly.  But let's land
the patch now so we can get on with other development.

Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane

free space information is stored in a dedicated FSM relation fork, with each
relation (except for hash indexes; they don't use FSM).

This eliminates the max_fsm_relations and max_fsm_pages GUC options; remove any
trace of them from the backend, initdb, and documentation.

Rewrite contrib/pg_freespacemap to match the new FSM implementation. Also
introduce a new variant of the get_raw_page(regclass, int4, int4) function in
contrib/pageinspect that let's you to return pages from any relation fork, and
a new fsm_page_contents() function to inspect the new FSM pages.

instead of listing all the columns returned by the underlying function.

initdb not forced since this patch doesn't actually change anything about
the stored form of the views.  It just means there's one less place to change
if someone wants to add columns to them.

value.  This means that hash index lookups are always lossy and have to be
rechecked when the heap is visited; however, the gain in index compactness
outweighs this when the indexed values are wide.  Also, we only need to
perform datatype comparisons when the hash codes match exactly, rather than
for every entry in the hash bucket; so it could also win for datatypes that
have expensive comparison functions.  A small additional win is gained by
keeping hash index pages sorted by hash code and using binary search to reduce
the number of index tuples we have to look at.

Xiao Meng

This commit also incorporates Zdenek Kotala's patch to isolate hash metapages
and hash bitmaps a bit better from the page header datastructures.