continue to recurse after eliminating a NOT-below-a-NOT, since the
contained subexpression will now be part of the top-level AND/OR structure
and so deserves to be simplified. The real-world impact of this is
probably minimal, since it'd require at least three levels of NOT to make
a difference, but it's still a bug.
Also remove some redundant tests for NULL subexpressions.
track shared relations in a separate hashtable, so that operations done
from different databases are counted correctly. Add proper support for
anti-XID-wraparound vacuuming, even in databases that are never connected
to and so have no stats entries. Miscellaneous other bug fixes.
Alvaro Herrera, some additional fixes by Tom Lane.
Also, write multiple WAL buffers out in one write() operation.
ITAGAKI Takahiro
---------------------------------------------------------------------------
> If we disable writeback-cache and use open_sync, the per-page writing
> behavior in WAL module will show up as bad result. O_DIRECT is similar
> to O_DSYNC (at least on linux), so that the benefit of it will disappear
> behind the slow disk revolution.
>
> In the current source, WAL is written as:
> for (i = 0; i < N; i++) { write(&buffers[i], BLCKSZ); }
> Is this intentional? Can we rewrite it as follows?
> write(&buffers[0], N * BLCKSZ);
>
> In order to achieve it, I wrote a 'gather-write' patch (xlog.gw.diff).
> Aside from this, I'll also send the fixed direct io patch (xlog.dio.diff).
> These two patches are independent, so they can be applied either or both.
>
>
> I tested them on my machine and the results as follows. It shows that
> direct-io and gather-write is the best choice when writeback-cache is off.
> Are these two patches worth trying if they are used together?
>
>
> | writeback | fsync= | fdata | open_ | fsync_ | open_
> patch | cache | false | sync | sync | direct | direct
> ------------+-----------+--------+-------+-------+--------+---------
> direct io | off | 124.2 | 105.7 | 48.3 | 48.3 | 48.2
> direct io | on | 129.1 | 112.3 | 114.1 | 142.9 | 144.5
> gather-write| off | 124.3 | 108.7 | 105.4 | (N/A) | (N/A)
> both | off | 131.5 | 115.5 | 114.4 | 145.4 | 145.2
>
> - 20runs * pgbench -s 100 -c 50 -t 200
> - with tuning (wal_buffers=64, commit_delay=500, checkpoint_segments=8)
> - using 2 ATA disks:
> - hda(reiserfs) includes system and wal.
> - hdc(jfs) includes database files. writeback-cache is always on.
>
> ---
> ITAGAKI Takahiro
An attached patch is a small additional improvement.
This patch use appendStringInfoText instead of appendStringInfoString.
There is an overhead of PG_TEXT_GET_STR when appendStringInfoString is
executed by text type. This can be reduced by appendStringInfoText.
Atsushi Ogawa
planning logic for bitmap indexscans. Partial indexes create corner
cases in which a scan might be done with no explicit index qual conditions,
and the code wasn't handling those cases nicely. Also be a little
tenser about eliminating redundant clauses in the generated plan.
Per report from Dmitry Karasik.
to the "text" segment. It would be possible to mark the elements of the
array "const" as well, but this would require multiple API changes and
does not seem to be worth the notational inconvenience.
into .def and .exp files automatically on Windows, AIX, and the like.
An additional benefit is that changes in libpgport files correctly
propagate to force rebuild of the backend executable. This is my
reworking of Rocco Altier's idea, and if it breaks anything it's
definitely my fault.
doesn't automatically inherit the privileges of roles it is a member of;
for such a role, membership in another role can be exploited only by doing
explicit SET ROLE. The default inherit setting is TRUE, so by default
the behavior doesn't change, but creating a user with NOINHERIT gives closer
adherence to our current reading of SQL99. Documentation still lacking,
and I think the information schema needs another look.
existing ones for object privileges. Update the information_schema for
roles --- pg_has_role() makes this a whole lot easier, removing the need
for most of the explicit joins with pg_user. The views should be a tad
faster now, too. Stephen Frost and Tom Lane.
pg_strcasecmp and pg_strncasecmp ... but I see some of the former have
crept back in.
Eternal vigilance is the price of locale independence, apparently.
near daylight savings time boudaries. This handles it properly, e.g.
test=> select '2005-04-03 04:00:00'::timestamp at time zone
'America/Los_Angeles';
timezone
------------------------
2005-04-03 07:00:00-04
(1 row)
test=> select (CURRENT_DATE + '05:00'::time)::timestamp at time zone
'Canada/Pacific';
timezone
------------------------
2005-07-22 08:00:00-04
(1 row)
test=> select ('2005-07-20 00:00:00'::timestamp without time zone) at
time zone 'Europe/Paris';
timezone
------------------------
2005-07-19 22:00:00-04
Udpate documentation.
coding would ignore startup cost differences of less than 1% of the
estimated total cost; which was OK for normal planning but highly not OK
if a very small LIMIT was applied afterwards, so that startup cost becomes
the name of the game. Instead, compare startup and total costs fuzzily
but independently. This changes the plan selected for two queries in the
regression tests; adjust expected-output files for resulting changes in
row order. Per reports from Dawid Kuroczko and Sam Mason.
24 hours. This is very helpful for daylight savings time:
select '2005-05-03 00:00:00 EST'::timestamp with time zone + '24 hours';
?column?
----------------------
2005-05-04 01:00:00-04
select '2005-05-03 00:00:00 EST'::timestamp with time zone + '1 day';
?column?
----------------------
2005-05-04 01:00:00-04
Michael Glaesemann
