(materialization into a tuple store) discussed on pgsql-hackers earlier.
I've updated the documentation and the regression tests.
Notes on the implementation:
- I needed to change the tuple store API slightly -- it assumes that it
won't be used to hold data across transaction boundaries, so the temp
files that it uses for on-disk storage are automatically reclaimed at
end-of-transaction. I added a flag to tuplestore_begin_heap() to control
this behavior. Is changing the tuple store API in this fashion OK?
- in order to store executor results in a tuple store, I added a new
CommandDest. This works well for the most part, with one exception: the
current DestFunction API doesn't provide enough information to allow the
Executor to store results into an arbitrary tuple store (where the
particular tuple store to use is chosen by the call site of
ExecutorRun). To workaround this, I've temporarily hacked up a solution
that works, but is not ideal: since the receiveTuple DestFunction is
passed the portal name, we can use that to lookup the Portal data
structure for the cursor and then use that to get at the tuple store the
Portal is using. This unnecessarily ties the Portal code with the
tupleReceiver code, but it works...
The proper fix for this is probably to change the DestFunction API --
Tom suggested passing the full QueryDesc to the receiveTuple function.
In that case, callers of ExecutorRun could "subclass" QueryDesc to add
any additional fields that their particular CommandDest needed to get
access to. This approach would work, but I'd like to think about it for
a little bit longer before deciding which route to go. In the mean time,
the code works fine, so I don't think a fix is urgent.
- (semi-related) I added a NO SCROLL keyword to DECLARE CURSOR, and
adjusted the behavior of SCROLL in accordance with the discussion on
-hackers.
- (unrelated) Cleaned up some SGML markup in sql.sgml, copy.sgml
Neil Conway
already fixed by You. However there were a few left and attached patch
should fix the rest of them.
I used StringInfo only in 2 places and both of them are inside debug
ifdefs. Only performance penalty will come from using strlen() like all
the other code does.
I also modified some of the already patched parts by changing
snprintf(buf, 2 * BUFSIZE, ... style lines to
snprintf(buf, sizeof(buf), ... where buf is an array.
Jukka Holappa
The local buffer manager is no longer used for newly-created relations
(unless they are TEMP); a new non-TEMP relation goes through the shared
bufmgr and thus will participate normally in checkpoints. But TEMP relations
use the local buffer manager throughout their lifespan. Also, operations
in TEMP relations are not logged in WAL, thus improving performance.
Since it's no longer necessary to fsync relations as they move out of the
local buffers into shared buffers, quite a lot of smgr.c/md.c/fd.c code
is no longer needed and has been removed: there's no concept of a dirty
relation anymore in md.c/fd.c, and we never fsync anything but WAL.
Still TODO: improve local buffer management algorithms so that it would
be reasonable to increase NLocBuffer.
As proof of concept, provide an alternate implementation based on POSIX
semaphores. Also push the SysV shared-memory implementation into a
separate file so that it can be replaced conveniently.
o Change all current CVS messages of NOTICE to WARNING. We were going
to do this just before 7.3 beta but it has to be done now, as you will
see below.
o Change current INFO messages that should be controlled by
client_min_messages to NOTICE.
o Force remaining INFO messages, like from EXPLAIN, VACUUM VERBOSE, etc.
to always go to the client.
o Remove INFO from the client_min_messages options and add NOTICE.
Seems we do need three non-ERROR elog levels to handle the various
behaviors we need for these messages.
Regression passed.
now just below FATAL in server_min_messages. Added more text to
highlight ordering difference between it and client_min_messages.
---------------------------------------------------------------------------
REALLYFATAL => PANIC
STOP => PANIC
New INFO level the prints to client by default
New LOG level the prints to server log by default
Cause VACUUM information to print only to the client
NOTICE => INFO where purely information messages are sent
DEBUG => LOG for purely server status messages
DEBUG removed, kept as backward compatible
DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1 added
DebugLvl removed in favor of new DEBUG[1-5] symbols
New server_min_messages GUC parameter with values:
DEBUG[5-1], INFO, NOTICE, ERROR, LOG, FATAL, PANIC
New client_min_messages GUC parameter with values:
DEBUG[5-1], LOG, INFO, NOTICE, ERROR, FATAL, PANIC
Server startup now logged with LOG instead of DEBUG
Remove debug_level GUC parameter
elog() numbers now start at 10
Add test to print error message if older elog() values are passed to elog()
Bootstrap mode now has a -d that requires an argument, like postmaster
upper limit on what we will believe from sysconf(_SC_OPEN_MAX). The
default value is 1000, so that under ordinary conditions it won't
affect the behavior. But on platforms where the kernel promises far
more than it can deliver, this can be used to prevent running out of
file descriptors. See numerous past discussions, eg, pgsql-hackers
around 23-Dec-2000.
cvs.
The Debian bug report says, "The upstream source makes use of NOFILE
unconditionalized. As the Hurd doesn't have an arbitrary limit on the
number of open files, this is not defined. But _SC_OPEN_MAX works fine
and returns 1024 (applications can increase this as they want), so I
suggest the below diff. Please forward this upstream, too."
Oliver Elphick
directory (which can be made a symlink to put temp files on another disk).
Add code to delete leftover temp files during postmaster startup.
Bruce, with some kibitzing from Tom.
checkpoint's redo pointer, not its undo pointer, per discussion in
pghackers a few days ago. No point in hanging onto undo information
until we have the ability to do something with it --- and this solves
a rather large problem with log space for long-running transactions.
Also, change all calls of write() to detect the case where write
returned a count less than requested, but failed to set errno.
Presume that this situation indicates ENOSPC, and give the appropriate
error message, rather than a random message associated with the previous
value of errno.
Python) to support shared extension modules, I have learned that Guido
prefers the style of the attached patch to solve the above problem.
I feel that this solution is particularly appropriate in this case
because the following:
PglargeType
PgType
PgQueryType
are already being handled in the way that I am proposing for PgSourceType.
Jason Tishler
VFD entries. On platforms where dereferencing a null pointer doesn't
lead to coredump, it's possible that this omission could have led to
unpleasant behavior like deleting the wrong file.
waste of cycles on single-CPU machines, and of dubious utility on multi-CPU
machines too.
Tweak s_lock_stuck so that caller can specify timeout interval, and
increase interval before declaring stuck spinlock for buffer locks and XLOG
locks.
On systems that have fdatasync(), use that rather than fsync() to sync WAL
log writes. Ensure that WAL file is entirely allocated during XLogFileInit.
are now critical sections, so as to ensure die() won't interrupt us while
we are munging shared-memory data structures. Avoid insecure intermediate
states in some code that proc_exit will call, like palloc/pfree. Rename
START/END_CRIT_CODE to START/END_CRIT_SECTION, since that seems to be
what people tend to call them anyway, and make them be called with () like
a function call, in hopes of not confusing pg_indent.
I doubt that this is sufficient to make SIGTERM safe anywhere; there's
just too much code that could get invoked during proc_exit().
virtual FDs, we just return the ENFILE/EMFILE error to the caller,
rather than immediate elog(). This allows more robust behavior in
the postmaster, which uses AllocateFile() but does not want elog().
> situation is already tracked in File routines, but a little bit
> incorrectly.
> After small survey in Linux kernel code, I am not sure about
> it. New patch set pos to unknown in the case of read/write
> fails. And do lseek again.
> Here is the full patch for this. This patch reduce amount of
> lseek call ten ti mes for update statement and twenty times for
> select statement. I tested joined up date and count(*) select
> for table with rows > 170000 and 10 indices. I think this is
> worse of trying. Before lseek calls account for more than 5% o
> f time. Now they are 0.89 and 0.15 respectevly.
>
> Due to only one file modification patch should be applied in
> src/backedn/stora ge/file/ dir.
-- Sincerely Yours,
Denis Perchine
it will close VFDs if necessary to surmount ENFILE or EMFILE failures.
Make use of this in md.c, xlog.c, and user.c routines that were
formerly vulnerable to these failures. In particular, this should
handle failures of mdblindwrt() that have been observed under heavy
load conditions. (By golly, every other process on the system may
crash after Postgres eats up all the kernel FDs, but Postgres will
keep going!)
That means you can now set your options in either or all of $PGDATA/configuration,
some postmaster option (--enable-fsync=off), or set a SET command. The list of
options is in backend/utils/misc/guc.c, documentation will be written post haste.
pg_options is gone, so is that pq_geqo config file. Also removed were backend -K,
-Q, and -T options (no longer applicable, although -d0 does the same as -Q).
Added to configure an --enable-syslog option.
changed all callers from TPRINTF to elog(DEBUG)
as a shared dirtybit for each shared buffer. The shared dirtybit still
controls writing the buffer, but the local bit controls whether we need
to fsync the buffer's file. This arrangement fixes a bug that allowed
some required fsyncs to be missed, and should improve performance as well.
For more info see my post of same date on pghackers.
