Обсуждение: getting better performance
Hello! I have a postgresql server serving thousands of tables. Sometime there are queries which involves several tables. In postgresql.conf I have these settings: shared_buffers = 40000 work_mem = 8192 maintenance_work_mem = 16384 max_stack_depth = 2048 all other settings are left by default (except ones needed for pg_autovacuum). Is there anything I can tune to get better performance? -- Eugene N Dzhurinsky
am 06.07.2006, um 9:40:16 +0300 mailte Eugeny N Dzhurinsky folgendes: > In postgresql.conf I have these settings: > > shared_buffers = 40000 > work_mem = 8192 > maintenance_work_mem = 16384 > max_stack_depth = 2048 > > all other settings are left by default (except ones needed for pg_autovacuum). > > Is there anything I can tune to get better performance? You can set "log_min_duration_statement" to log slow querys and then analyse this querys. HTH, Andreas -- Andreas Kretschmer (Kontakt: siehe Header) Heynitz: 035242/47215, D1: 0160/7141639 GnuPG-ID 0x3FFF606C http://wwwkeys.de.pgp.net === Schollglas Unternehmensgruppe ===
On 7/6/06, A. Kretschmer <andreas.kretschmer@schollglas.com> wrote: > am 06.07.2006, um 9:40:16 +0300 mailte Eugeny N Dzhurinsky folgendes: > > In postgresql.conf I have these settings: > > > > shared_buffers = 40000 > > work_mem = 8192 > > maintenance_work_mem = 16384 > > max_stack_depth = 2048 > > > > all other settings are left by default (except ones needed for pg_autovacuum). > > > > Is there anything I can tune to get better performance? > > You can set "log_min_duration_statement" to log slow querys and then > analyse this querys. When you collect your logs try PgFouine http://pgfouine.projects.postgresql.org/ to understand what queries should be optimized and what's the reason of poor performance.
On Thu, 2006-07-06 at 01:40, Eugeny N Dzhurinsky wrote: > Hello! > > I have a postgresql server serving thousands of tables. Sometime there are > queries which involves several tables. Do you add / remove tables a lot? Could be you've got system catalog bloat. do you have autovacuum running? What version of pgsql are you running? What OS? What file system? What kind of machine are you using? How much memory does it have? How many disk drives? Are you using RAID? hardware / software? battery backed cache or no? Do you have one or two, or thousands of connections at a time? Do you use connection pooling if you have lots of connections to handle? There's a lot of info needed to make a decision on how to performance tune a system.
On Thu, Jul 06, 2006 at 09:28:39AM -0500, Scott Marlowe wrote: > On Thu, 2006-07-06 at 01:40, Eugeny N Dzhurinsky wrote: > Do you add / remove tables a lot? Could be you've got system catalog > bloat. Yes, almost each table is dropped and re-created in 3-5 days. > do you have autovacuum running? Yes. > What version of pgsql are you running? psql -V psql (PostgreSQL) 8.0.0 > What OS? CentOS release 3.7 (Final) > What file system? ext3 > What kind of machine are you using? Pentium IV, 1.8 GHz > How much memory does it have? 512 Mb RAM > How many disk drives? single > Are you using RAID? hardware / software? battery backed cache or no? no > Do you have one or two, or thousands of connections at a time? something like 20 connections (peak). > Do you use connection pooling if you have lots of connections to handle? My application uses Jakarta Commons DBCP module. -- Eugene Dzhurinsky
On 7/6/06, Eugeny N Dzhurinsky <bofh@redwerk.com> wrote: > Hello! > > I have a postgresql server serving thousands of tables. Sometime there are > queries which involves several tables. > In postgresql.conf I have these settings: > > shared_buffers = 40000 > work_mem = 8192 > maintenance_work_mem = 16384 > max_stack_depth = 2048 > > all other settings are left by default (except ones needed for pg_autovacuum). > > Is there anything I can tune to get better performance? you may want to explore upping your FSM settings with that many tables. Merlin
On Thu, 2006-07-06 at 10:11, Eugeny N Dzhurinsky wrote: > On Thu, Jul 06, 2006 at 09:28:39AM -0500, Scott Marlowe wrote: > > On Thu, 2006-07-06 at 01:40, Eugeny N Dzhurinsky wrote: > > Do you add / remove tables a lot? Could be you've got system catalog > > bloat. > > Yes, almost each table is dropped and re-created in 3-5 days. > > do you have autovacuum running? > > Yes. Hopefully, that will keep the system catalogs from getting overly fat. You still need to check their size every so often to make sure they're not getting out of line. you might wanna run a vacuum verbose and see what it has to say. > > What version of pgsql are you running? > > psql -V > psql (PostgreSQL) 8.0.0 You should update. x.0.0 versions often have the nastiest of the data loss bugs of any release versions of postgresql. 8.0 is up to 8.0.8 now. The upgrades are generally painless (backup anyway, just in case) and can be done in place. just down postgres, rpm -Uvh the packages and restart postgres > > What OS? > > CentOS release 3.7 (Final) > > > What file system? > > ext3 > > > What kind of machine are you using? > > Pentium IV, 1.8 GHz > > > How much memory does it have? > > 512 Mb RAM That's kind of small for a database server. If your data set is fairly small it's alright, but if you're working on gigs of data in your database, the more memory the better. > > How many disk drives? > > single OTOH, if you're doing a lot of committing / writing to the hard drives, a single disk drive is suboptimal Is this SCSI, PATA or SATA? If it's [SP]ATA, then you've likely got no real fsyncing, and while performance won't be a problem, reliability should the machine crash would be. If it's SCSI, then it could be a bottle neck for writes. > > Are you using RAID? hardware / software? battery backed cache or no? > > no I'd recommend looking into it, unless you're CPU bound. A decent RAID controller with battery backed cache and a pair of drives in a mirror setup can be a marked improved to start with, and you can add more drives as time goes by if needs be. My guess is that you've got sys catalog bloat. You might have to down the database to single user mode and run a vacuum on the system catalogs from there. That's how it was in the old days of 7.x databases anyway. If you don't have sys cat bloat, then you're probably CPU / memory bound right now. unless you're writing a lot, then you're likely disk i/o bound, but I kinda doubt it.
Hi, Eugeny, Eugeny N Dzhurinsky wrote: >> Do you add / remove tables a lot? Could be you've got system catalog >> bloat. > > Yes, almost each table is dropped and re-created in 3-5 days. If your really recreate the same table, TRUNCATE may be a better solution than dropping and recreation. HTH, Markus -- Markus Schaber | Logical Tracking&Tracing International AG Dipl. Inf. | Software Development GIS Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org