SearchCatCacheList and ReleaseCatCacheList. Previously, we incremented
and decremented the refcounts of list member tuples along with the list
itself, but that's unnecessary, and very expensive when the list is big.
It's cheaper to change only the list refcount. When we are considering
deleting a cache entry, we have to check not only its own refcount but
its parent list's ... but it's easy to arrange the code so that this
check is not made in any commonly-used paths, so the cost is really nil.
The bigger gain though is to refrain from DLMoveToFront'ing each individual
member tuple each time the list is referenced. To keep some semblance
of fair space management, lists are just marked as used or not since the
last cache cleanout search, and we do a MoveToFront pass only when about
to run a cleanout. In combination, these changes reduce the costs of
SearchCatCacheList and ReleaseCatCacheList from about 4.5% of pgbench
runtime to under 1%, according to my gprof results.
remember the output parameter set for himself. It's a bit of a kluge
but fixing array_in to work in bootstrap mode looks worse.
I removed the separate pg_file_length() function, as it no longer has any
real notational advantage --- you can write (pg_stat_file(...)).length.
stderr-in-service or output-from-syslogger-in-service code. Previously
everything was flagged as ERRORs there, which caused all instances to
log "LOG: logger shutting down" as error...
Please apply for 8.1. I'd also like it considered for 8.0 since logging
non-errors as errors can be cause for alarm amongst people who actually
look at their logs...
Magnus Hagander
> >> 3) I restarted the postmaster both times. I got this error
> both times.
> >> :25: ERROR: could not load library "C:/Program
> >> Files/PostgreSQL/8.0/lib/testtrigfuncs.dll": dynamic load error
>
> > Yes. We really need to look at fixing that error message. I had
> > forgotten it completely :-(
>
> > Bruce, you think we can sneak that in after feature freeze? I would
> > call it a bugfix :-)
>
> Me too. That's been on the radar for awhile --- please do
> send in a patch.
Here we go, that wasn't too hard :-)
Apart from adding the error handling, it does one more thing: it changes
the errormode when loading the DLLs. Previously if a DLL was broken, or
referenced other DLLs that couldn't be found, a popup dialog box would
appear on the screen. Which had to be clicked before the backend could
continue. This patch also disables the popup error message for DLL
loads.
I think this is something we should consider doing for the entire
backend - disable those popups, and say we deal with it ourselves. What
do you other win32 hackers thinnk about this?
In the meantime, this patch fixes the error msgs. Please apply for 8.1
and please consider a backpatch to 8.0.
Magnus Hagander
> > I ran across this yesterday on HEAD:
>
> > template1=# grant select on foo, foo to swm;
> > ERROR: tuple already updated by self
>
> Seems to fail similarly in every version back to 7.2; probably further,
> but that's all I have running at the moment.
>
> > We could do away with the error by producing a unique list of object names
> > -- but that would impose an extra cost on the common case.
>
> CommandCounterIncrement in the GRANT loop would be easier, likely.
> I'm having a hard time getting excited about it though...
Yeah, its not that exciting but that error message would throw your
average user.
I've attached a patch which calls CommandCounterIncrement() in each of the
grant loops.
Gavin Sherry
should surely be timestamptz not timestamp; fix some but not all of the
holes in check_and_make_absolute(); other minor cleanup. Also put in
the missed catversion bump.
computation. On modern machines this is as fast if not faster, and we
don't have to clog the CPU's L2 cache with a tens-of-KB pointer array.
If we ever decide to adopt a more dynamic allocation method for shared
buffers, we'll probably have to revert this patch, but in the meantime
we might as well save a few bytes and nanoseconds. Per Qingqing Zhou.
whenever we generate a new OID. This prevents occasional duplicate-OID
errors that can otherwise occur once the OID counter has wrapped around.
Duplicate relfilenode values are also checked for when creating new
physical files. Per my recent proposal.
delay and limit, both as global GUCs and as table-specific entries in
pg_autovacuum. stats_reset_on_server_start is now OFF by default,
but a reset is forced if we did WAL replay. XID-wrap vacuums do not
ANALYZE, but do FREEZE if it's a template database. Alvaro Herrera
against the PGPROC array. Anything in the file that isn't in PGPROC
gets rejected as being a stale entry. This should solve complaints about
stale entries in pg_stat_activity after a BETERM message has been dropped
due to overload.
ResourceOwner mechanism already released all reference counts for the
cache entries; therefore, we do not need to scan the catcache or relcache
at transaction end, unless we want to do it as a debugging crosscheck.
Do the crosscheck only in Assert mode. This is the same logic we had
previously installed in AtEOXact_Buffers to avoid overhead with large
numbers of shared buffers. I thought it'd be a good idea to do it here
too, in view of Kari Lavikka's recent report showing a real-world case
where AtEOXact_CatCache is taking a significant fraction of runtime.
exit, instead of trying to take shortcuts. Introduce some additional
shutdown callback routines to eliminate kluges like having ProcKill
be responsible for shutting down the buffer manager. Ensure that the
order of operations during shutdown is predictable and what you would
expect given the module layering.
max_files_per_process. Going further than that is just a waste of
cycles, and it seems that current Cygwin does not cope gracefully
with deliberately running the system out of FDs. Per Andrew Dunstan.
character, tighten the inner loops of CopyReadLine and CopyReadAttribute,
arrange to parse out all the attributes of a line in just one call instead
of one CopyReadAttribute call per attribute, be smarter about which client
encodings require slow pg_encoding_mblen() loops. Also, clean up the
mishmash of static variables and overly-long parameter lists in favor of
passing around a single CopyState struct containing all the state data.
Original patch by Alon Goldshuv, reworked by Tom Lane.
This was not especially critical before, but it is now that we track
ownership dependencies --- the dependency for the rowtype *must* shift
to the new owner. Spotted by Bernd Helmle.
Also fix a problem introduced by recent change to allow non-superusers
to do ALTER OWNER in some cases: if the table had a toast table, ALTER
OWNER failed *even for superusers*, because the test being applied would
conclude that the new would-be owner had no create rights on pg_toast.
A side-effect of the fix is to disallow changing the ownership of indexes
or toast tables separately from their parent table, which seems a good
idea on the whole.
doesn't block the bgwriter from making progress writing out other buffers.
This was a hard problem in the context of the ARC/2Q design, but it's
trivial in the context of clock sweep ... just advance the sweep counter
before we try to write not after.
of special case for Windows port. Put a PG_TRY around most of createdb()
to ensure that we remove copied subdirectories on failure, even if the
failure happens while creating the pg_database row. (I think this explains
Oliver Siegmar's recent report.) Having done that, there's no need for
the fragile assumption that copydir() mustn't ereport(ERROR), so simplify
its API. Eliminate the old code that used system("cp ...") to copy
subdirectories, in favor of using copydir() on all platforms. This not
only should allow much better error reporting, but allows us to fsync
the created files before trusting that the copy has succeeded.
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
