Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Martijn van Oosterhout
On Sun, Nov 27, 2005 at 05:45:31PM -0500, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: COPY FROM can read in sufficient rows until it has a whole block worth of data, then get a new block and write it all with one pair of BufferLock calls. Comments? I don't see any way to do

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Simon Riggs
On Mon, 2005-11-28 at 09:40 +0100, Martijn van Oosterhout wrote: On Sun, Nov 27, 2005 at 05:45:31PM -0500, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: COPY FROM can read in sufficient rows until it has a whole block worth of data, then get a new block and write it all with one

Re: [HACKERS][OT] Doubt

2005-11-28 Thread Csaba Nagy
http://acronymfinder.com/ Cheers, Csaba. On Fri, 2005-11-25 at 19:24, Gustavo Tonini wrote: What is ISTM? Sorry, Gustavo. ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Simon Riggs
On Sun, 2005-11-27 at 17:45 -0500, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: COPY FROM can read in sufficient rows until it has a whole block worth of data, then get a new block and write it all with one pair of BufferLock calls. Comments? I don't see any way to do this

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Alvaro Herrera
Simon Riggs wrote: On Sun, 2005-11-27 at 17:45 -0500, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: COPY FROM can read in sufficient rows until it has a whole block worth of data, then get a new block and write it all with one pair of BufferLock calls. Comments? I

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Hannu Krosing
On Mon, 2005-11-28 at 00:56 +, Simon Riggs wrote: On Sun, 2005-11-27 at 17:45 -0500, Tom Lane wrote: Simon Riggs [EMAIL PROTECTED] writes: COPY FROM can read in sufficient rows until it has a whole block worth of data, then get a new block and write it all with one pair of

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Martijn van Oosterhout
On Mon, Nov 28, 2005 at 09:39:36AM +, Simon Riggs wrote: On Mon, 2005-11-28 at 09:40 +0100, Martijn van Oosterhout wrote: Whatever happened to that idea to build as entire datafile with COPY or some external tool and simply copy it into place and update the catalog? What's wrong with

[HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Mario Weilguni
I've a problem that might be a bug in the core system (hashjoins) or with ltree using gist-index, but I fail miserable to produce a useful testcase (using 8.1, worked in 8.0): A query produces wrong (=0) results, when a different plan is enforced, I get a merge-join plan that looks similar,

Re: [HACKERS] Getting different number of results when using hashjoin

2005-11-28 Thread Christopher Kings-Lynne
The path field is an ltree column, with an GIST index on it. Something to do with bitmap indexscans on lossy indexes? Chris ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Mario Weilguni
Am Montag, 28. November 2005 14:12 schrieb Christopher Kings-Lynne: The path field is an ltree column, with an GIST index on it. Something to do with bitmap indexscans on lossy indexes? Chris I doubt that, set enable_bitmapscan to off produces the wrong result as well. Best regards Mario

[HACKERS] What's wrong with the lists?

2005-11-28 Thread Alvaro Herrera
Hi, Is there something weird going on with the lists? I ask because lately there has been spam showing up rather frequently, something that happenned only very ocassionally. Has there been a change from human moderation to robotical approval of messages? Also, my last auto-mails to

[HACKERS] Allow an alias for the target table in UPDATE

2005-11-28 Thread Atsushi Ogawa
I am interested in a following item in TODO. o Allow an alias to be provided for the target table in UPDATE/DELETE This is not SQL-spec but many DBMSs allow it. I think that this functionality is useful for the migration from other RDBMS. However the SQL92 spec does not allow an alias for

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Tom Lane
Alvaro Herrera [EMAIL PROTECTED] writes: I don't see why couldn't have an additional index access method entry point to insert multiple rows on one call. I think Simon was mainly on about the idea of inserting multiple *heap* entries with one call, ie, only one cycle of locking a heap buffer.

[HACKERS] Ipv6 and Postgresql 8.0.3

2005-11-28 Thread R, Rajesh (STSD)
PLZ REPLY Hello there, I run Postgresql 8.0.3 on Tru64 Unix m/c. I have included the ipv6 auth. line in my pg_hba.conf file(::1/128) I keep getting error msgs from postmaster everytime I try to connect. Going by previous posts on the topic am unable to conclude. Does this mean pg 8.0.3

Re: [HACKERS] Ipv6 and Postgresql 8.0.3

2005-11-28 Thread Andrew Dunstan
First, do not name the mailing list in both the To: and Cc: lines - that's just redundant. Second, this is the wrong list to ask this question, as you were told last time. Ask on the pgsql-general list. cheers andrew R, Rajesh (STSD) wrote: PLZ REPLY Hello there, I run Postgresql

Re: [HACKERS] Ipv6 and Postgresql 8.0.3

2005-11-28 Thread Tom Lane
Andrew Dunstan [EMAIL PROTECTED] writes: First, do not name the mailing list in both the To: and Cc: lines - that's just redundant. Second, this is the wrong list to ask this question, as you were told last time. Ask on the pgsql-general list. And third, show us the darn error messages ...

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Tom Lane
Mario Weilguni [EMAIL PROTECTED] writes: The failing case is: ... SubPlan - Hash Join (cost=8.47..19.46 rows=1 width=0) (actual time=0.004..0.004 rows=0 loops=21619) Hash Cond: (outer.id = inner.str_id) - Bitmap Heap Scan on structure str (cost=2.02..12.92

[HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
G'day folks. We have a production database running 8.0.3 which gets fully pg_dump'd and vacuum analyze'd hourly by cron. Something strange happened to us on the 5AM Friday Nov. 25'th cron run -- the: /usr/local/pgsql/bin/vacuumdb -U postgres --all --analyze --verbose $DATE/vacuum.log

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread Tom Lane
James Robinson [EMAIL PROTECTED] writes: Comparing the logs further with when it did complete, it seems that one table in particular (at least) seems afflicted: social=# vacuum verbose analyze agency.swlog_client; hangs up forever -- have to control-c the client. Likewise for w/o

[HACKERS] Anonymous CVS working?

2005-11-28 Thread Michael Fuhr
Any problems with CVS or anonymous CVS since the work last evening? Anonymous CVS hasn't given me the following commit yet; it's been almost twelve hours since it was made: http://archives.postgresql.org/pgsql-committers/2005-11/msg00553.php -- Michael Fuhr ---(end of

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Tom Lane
Mario Weilguni [EMAIL PROTECTED] writes: Yes. This is from a 8.0.3 (with slightly older and different data, resulting in only 9 rows, but the rest is the same): Yeah, that looks more reasonable. I tried to reproduce this, without any luck: regression=# explain analyze select count(*) from

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
As fate would have it, the vacuumdb frontend and backend which were initially afflicted are still in existence: sscadmin 19236 19235 0 Nov25 ?00:00:00 /usr/local/pgsql/bin/ vacuumdb -U postgres --all --analyze --verbose postgres 19244 3596 0 Nov25 ?00:00:02 postgres:

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread Tom Lane
James Robinson [EMAIL PROTECTED] writes: As fate would have it, the vacuumdb frontend and backend which were initially afflicted are still in existence: OK, so pid 19244 isn't blocked on any lmgr lock; else we'd see an entry with granted = f for it in pg_locks. It could be blocked on a lower

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Mario Weilguni
Thanks Tom for you quick answer! No, I'm using 8.1.0, and tried it on different machines, always the same results. SELECT version(); PostgreSQL 8.1.0 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.3.4 20040623 (Gentoo Hardened Linux 3.3.4-r1, ssp-3.3.2-2, pie-8.7.6) Best regards,

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
Here ya go -- BTW -- your guys support is the _best_. But you know that already: [EMAIL PROTECTED]:/home/sscadmin gdb /usr/local/pgsql/bin/postgres 19244 GNU gdb 6.2.1 Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread Tom Lane
James Robinson [EMAIL PROTECTED] writes: (gdb) bt #0 0xe410 in ?? () #1 0xbfffd508 in ?? () #2 0x082aef97 in PqSendBuffer () #3 0xbfffd4f0 in ?? () #4 0xb7ec03e1 in send () from /lib/tls/libc.so.6 #5 0x08137d27 in secure_write () #6 0x0813c2a7 in internal_flush () #7

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
On Nov 28, 2005, at 11:38 AM, Tom Lane wrote: Can you get a similar backtrace from the vacuumdb process? (Obviously, give gdb the vacuumdb executable not the postgres one.) OK: (gdb) bt #0 0xe410 in ?? () #1 0xbfffe4f8 in ?? () #2 0x0030 in ?? () #3 0x08057b68 in ?? () #4

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread Tom Lane
James Robinson [EMAIL PROTECTED] writes: On Nov 28, 2005, at 11:38 AM, Tom Lane wrote: Can you get a similar backtrace from the vacuumdb process? OK: (gdb) bt #0 0xe410 in ?? () #1 0xbfffe4f8 in ?? () #2 0x0030 in ?? () #3 0x08057b68 in ?? () #4 0xb7e98533 in

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Tom Lane
Mario Weilguni [EMAIL PROTECTED] writes: No, I'm using 8.1.0, and tried it on different machines, always the same results. I see it, I think: the recent changes to avoid work when one or the other side of the hash join is empty would exit the hash join leaving a state that confused

Re: [HACKERS] Anonymous CVS working?

2005-11-28 Thread Tom Lane
Michael Fuhr [EMAIL PROTECTED] writes: Any problems with CVS or anonymous CVS since the work last evening? The master CVS is fine, but I agree that the anonymous mirror doesn't seem to be tracking it ... regards, tom lane ---(end of

Re: [HACKERS] Anonymous CVS working?

2005-11-28 Thread Alvaro Herrera
Tom Lane wrote: Michael Fuhr [EMAIL PROTECTED] writes: Any problems with CVS or anonymous CVS since the work last evening? The master CVS is fine, but I agree that the anonymous mirror doesn't seem to be tracking it ... Apparently the CVSup server is down too. I wonder if the anon CVS

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Mario Weilguni
Hello Tom, Thanks for the quick response, I've tried the patch, but it did not work as expected. When I set enable_hashjoin to off, everything works as expected, but with hashjoin on I do not even get results anymore, CPU is going up to 100% and after 3 minutes I cancelled the query (it normale

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
On Nov 28, 2005, at 12:00 PM, Tom Lane wrote: Your next move is to look at the state of sshd and whatever is running at the client end of the ssh tunnel. backtrace of the sshd doesn't look good: (gdb) bt #0 0xe410 in ?? () #1 0xbfffdb48 in ?? () #2 0x080a1e28 in ?? () #3 0x080a1e78

Re: [HACKERS] Getting different number of results when using hashjoin on/off

2005-11-28 Thread Mario Weilguni
Yes. This is from a 8.0.3 (with slightly older and different data, resulting in only 9 rows, but the rest is the same): Index Scan using ben_uk3 on foo1 ben (cost=0.00..73867.23 rows=863 width=27) (actual time=38.591..501.839 rows=9 loops=1) Filter: (subplan) SubPlan - Hash Join

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread Tom Lane
James Robinson [EMAIL PROTECTED] writes: backtrace of the sshd doesn't look good: Stripped executable :-( ... you won't get much info there. What of the client at the far end of the ssh connection? You should probably assume that the blockage is there, rather than in a commonly used bit of

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread Tom Lane
James Robinson [EMAIL PROTECTED] writes: Given the other culprits in play are bash running a straightforward shellscript line with redirected output to a simple file on a non- full filesystem, I'm leaning more towards the odds that something related to the sshd + tcp/ip + ssh client

Re: [HACKERS] Anonymous CVS working?

2005-11-28 Thread Marc G. Fournier
cvsup back up and running ... On Mon, 28 Nov 2005, Alvaro Herrera wrote: Tom Lane wrote: Michael Fuhr [EMAIL PROTECTED] writes: Any problems with CVS or anonymous CVS since the work last evening? The master CVS is fine, but I agree that the anonymous mirror doesn't seem to be tracking it

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
On Nov 28, 2005, at 1:46 PM, Tom Lane wrote: James Robinson [EMAIL PROTECTED] writes: backtrace of the sshd doesn't look good: Stripped executable :-( ... you won't get much info there. What of the client at the far end of the ssh connection? You should probably assume that the blockage

Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off)

2005-11-28 Thread Tom Lane
Mario Weilguni [EMAIL PROTECTED] writes: Thanks for the quick response, I've tried the patch, but it did not work as expected. When I set enable_hashjoin to off, everything works as expected, but with hashjoin on I do not even get results anymore, CPU is going up to 100% and after 3 minutes I

Re: [HACKERS] Anonymous CVS working?

2005-11-28 Thread Marc G. Fournier
On Mon, 28 Nov 2005, Alvaro Herrera wrote: Tom Lane wrote: Michael Fuhr [EMAIL PROTECTED] writes: Any problems with CVS or anonymous CVS since the work last evening? The master CVS is fine, but I agree that the anonymous mirror doesn't seem to be tracking it ... Apparently the CVSup

Re: Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off)

2005-11-28 Thread Mario Weilguni
Title: AW: Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off) If the query runs slow it will be not such a problem, but I was very concerned about other queries having this problem too - without knowing it. I've already rewritten the

Re: [HACKERS] Help: 8.0.3 Vacuum of an empty table never completes ...

2005-11-28 Thread James Robinson
On Nov 28, 2005, at 4:13 PM, Tom Lane wrote: Yeah, could be. Anyway it doesn't seem like we can learn much more today. You might as well just zing the vacuumdb process and let things get back to normal. If it happens again, we'd have reason to dig deeper. Final report [ and apologies to

Re: [HACKERS] comment doesn't accept expressions returning text

2005-11-28 Thread Bruce Momjian
Added to TODO: * Allow COMMENT ON to accept an expression rather than just a string --- Michael Glaesemann wrote: I've been trying to be better at documentation in general and have been trying to

Re: [HACKERS] POWER vs. POW ???

2005-11-28 Thread Bruce Momjian
Christopher Kings-Lynne wrote: Also, POW() is not documented here: I think POW is just there for backward compatibility and people should use POWER(). ---

Re: [HACKERS] TRUNC vs. TRUNCATE

2005-11-28 Thread Bruce Momjian
Christopher Kings-Lynne wrote: Hi, I notice we added CEILING() as an alias to CEIL() for compatibility. We also have POWER() for POW(). I notice that MySQL uses TRUNCATE() and we only have TRUNC(). Is TRUNCATE actually spec compliant? Should we add TRUNCATE anyway for I don't see

Re: [HACKERS] NVL vs COALESCE

2005-11-28 Thread Bruce Momjian
Michael Glaesemann wrote: On Nov 24, 2005, at 21:21 , Marcus Engene wrote: When we're having an alias discussion, I'd really like to see NVL in postgres. Not because of porting from oracle as much as just spelling that without the reference manual is completely impossible. NVL:

Re: Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off)

2005-11-28 Thread Tom Lane
I wrote: For a query like this, where the hash join is being done repeatedly, it might be useful for the executor itself to track how often each subplan has been seen to be empty. I implemented a simple form of this, and it made 8.1 faster than 8.0 on the test case I was using. Give it a try

Re: Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off)

2005-11-28 Thread Tom Lane
Greg Stark [EMAIL PROTECTED] writes: I suspect this is obvious but since you asked, there isn't any way to keep around the hash table and just reuse it repeatedly instead of having to rescan the data over and over is there? We already do that when possible --- which it's not in the particular

Re: [HACKERS] gprof SELECT COUNT(*) results

2005-11-28 Thread Jim C. Nasby
On Fri, Nov 25, 2005 at 10:20:11AM -0500, Tom Lane wrote: Qingqing Zhou [EMAIL PROTECTED] writes: I can see your computer is really slow, so my theory is that since it is easy to hold a running-slowly horse than a fast one, so my spinlock on a 2.4G modern machine should takes relatively

Re: [HACKERS] gprof SELECT COUNT(*) results

2005-11-28 Thread Tom Lane
Jim C. Nasby [EMAIL PROTECTED] writes: (What would be the profiler to use on FBSD?) gprof should work fine. regards, tom lane ---(end of broadcast)--- TIP 6: explain analyze is your friend

Re: [HACKERS] Using multi-row technique with COPY

2005-11-28 Thread Jim C. Nasby
On Sun, Nov 27, 2005 at 07:44:55PM +, Simon Riggs wrote: not have any unique indexes or row triggers. It should be possible to take advantage of this automatically when those requirements are met, without any new options. Just as it was with Seq Scans, this is worth about 10% reduction in

Re: Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off)

2005-11-28 Thread Greg Stark
Tom Lane [EMAIL PROTECTED] writes: In particular, the executor knows that the outer subplan is parameterless and therefore should deliver the same results each time (modulo volatile functions of course), so after the first cycle it could know that there's no point in trying the early fetch

Re: [HACKERS] Allow an alias for the target table in UPDATE

2005-11-28 Thread Bruce Momjian
Atsushi Ogawa wrote: I am interested in a following item in TODO. o Allow an alias to be provided for the target table in UPDATE/DELETE This is not SQL-spec but many DBMSs allow it. I think that this functionality is useful for the migration from other RDBMS. However the SQL92 spec

[HACKERS] Checking a heap page

2005-11-28 Thread Bruce Momjian
With the applied patch that checks an entire heap page with one lock, is there any advantage of considering this for index pages? -- Bruce Momjian| http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, |

Re: [HACKERS] Checking a heap page

2005-11-28 Thread Tom Lane
Bruce Momjian pgman@candle.pha.pa.us writes: With the applied patch that checks an entire heap page with one lock, is there any advantage of considering this for index pages? Done already (see bitmap index scans). regards, tom lane ---(end of

[HACKERS] ice-broker scan thread

2005-11-28 Thread Qingqing Zhou
I am considering add an ice-broker scan thread to accelerate PostgreSQL sequential scan IO speed. The basic idea of this thread is just like the read-ahead method, but the difference is this one does not read the data into shared buffer pool directly, instead, it reads the data into file system

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread David Boreham
Qingqing Zhou wrote: I am considering add an ice-broker scan thread to accelerate PostgreSQL sequential scan IO speed. The basic idea of this thread is just like the read-ahead method, but the difference is this one does not read the data into shared buffer pool directly, instead, it reads the

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Gavin Sherry
On Mon, 28 Nov 2005, Qingqing Zhou wrote: I am considering add an ice-broker scan thread to accelerate PostgreSQL sequential scan IO speed. The basic idea of this thread is just like the read-ahead method, but the difference is this one does not read the data into shared buffer pool

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Christopher Kings-Lynne
Qingqing, I am considering add an ice-broker scan thread to accelerate PostgreSQL sequential scan IO speed. The basic idea of this thread is just like the read-ahead method, but the difference is this one does not read the data into shared buffer pool directly, instead, it reads the data into

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread David Boreham
Gavin Sherry wrote: MySQL, Oracle and others implement read-ahead threads to simulate async IO I always believed that Oracle used async file I/O. Not that I've seen their code, but I'm fairly sure they funded the addition of kernel aio to Linux a few years back. ButOracle comes from a

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Gavin Sherry
On Mon, 28 Nov 2005, David Boreham wrote: Gavin Sherry wrote: MySQL, Oracle and others implement read-ahead threads to simulate async IO I always believed that Oracle used async file I/O. Not that I've seen their code, but I'm fairly sure they funded the addition of kernel aio to Linux a

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Mark Kirkwood
Tom Lane wrote: Gavin Sherry [EMAIL PROTECTED] writes: I haven't had time to prototype whether we can easily implement async IO Just as with any suggestion to depend on threads, you are going to have to show results that border on astounding to have any chance of getting this in. Otherwise

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread David Boreham
The paper I linked to seemed to suggest that they weren't using async IO in 9.2 -- which is fairly old. I'm not sure why the authors didn't test 10g. ...reads paper... ok, interesting. Did they say that Oracle isn't using aio ? I can't see that. They that Oracle has no more than one

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Gavin Sherry
On Mon, 28 Nov 2005, Tom Lane wrote: Gavin Sherry [EMAIL PROTECTED] writes: I haven't had time to prototype whether we can easily implement async IO Just as with any suggestion to depend on threads, you are going to have to show results that border on astounding to have any chance of

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Mark Kirkwood
Gavin Sherry wrote: The paper I linked to seemed to suggest that they weren't using async IO in 9.2 -- which is fairly old. I'm not sure why the authors didn't test 10g. There have been async io type parameters in Oracle's init.ora files from (at least) 8i (disk_async_io=true IIRC) - on

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Qingqing Zhou
On Mon, 28 Nov 2005, Mark Kirkwood wrote: Do these ideas require threads in principle? ISTM that there could be (additional) process(es) waiting to perform pre-fetching or async io, and we could use the usual IPC machinary to talk between them... Right. I use threads because it is easy to

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Jonah H. Harris
FYI, I've personally used Oracle 9.2.0.4's async IO on Linux and have seen several installations which make use of it also. On 11/28/05, Gavin Sherry [EMAIL PROTECTED] wrote: On Mon, 28 Nov 2005, Tom Lane wrote: Gavin Sherry [EMAIL PROTECTED] writes: I haven't had time to prototype whether we

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Qingqing Zhou
On Mon, 28 Nov 2005, Gavin Sherry wrote: MySQL, Oracle and others implement read-ahead threads to simulate async IO 'pre-fetching'. Due to my tests on Windows (using the attached program and change enable_aio=true), seems aio doesn't help as a separate thread - but maybe because my usage is

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Qingqing Zhou
On Mon, 28 Nov 2005, Gavin Sherry wrote: I didn't want to jump on list and waive my hands until I had something to show, but since Qingqing is looking at the issue I thought I better raise it. Don't worry :-) I separate the logic into a standalone program in order to let more people can

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Qingqing Zhou
David Boreham [EMAIL PROTECTED] wrote BTW, I heard a long time ago that NTFS has quite fancy read-ahead, where it attempts to detect the application's access pattern including if it is reading sequentially and even if there is a 'stride' to the accesses when they're not contiguous. I would

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread David Boreham
Qingqing Zhou wrote: On Mon, 28 Nov 2005, Gavin Sherry wrote: MySQL, Oracle and others implement read-ahead threads to simulate async IO 'pre-fetching'. Due to my tests on Windows (using the attached program and change enable_aio=true), seems aio doesn't help as a

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Gavin Sherry
On Mon, 28 Nov 2005, Qingqing Zhou wrote: On Mon, 28 Nov 2005, Gavin Sherry wrote: MySQL, Oracle and others implement read-ahead threads to simulate async IO 'pre-fetching'. Due to my tests on Windows (using the attached program and change enable_aio=true), seems aio doesn't help as a

Re: [HACKERS] ice-broker scan thread

2005-11-28 Thread Qingqing Zhou
David Boreham [EMAIL PROTECTED] wrote I don't think your NT overlapped I/O code is quite right. At least I think it will issue reads at a high rate without waiting for any of them to complete. Beyond some point that has to give the kernel gut-rot. [also with reply to Gavin] look up