Hello ! Am Freitag 26 Januar 2007 12:28 schrieb John Parnefjord: > Hi! > > I'm planning to move from mysql to postgresql as I believe the latter > performs better when it comes to complex queries. The mysql database > that I'm running is about 150 GB in size, with 300 million rows in the > largest table. We do quite a lot of statistical analysis on the data > which means heavy queries that run for days. Now that I've got two new > servers with 32GB of ram I'm eager to switch to postgresql to improve > perfomance. One database is to be an analysis server and the other an > OLTP server feeding a web site with pages. > > I'm setting for Postgresql 8.1 as it is available as a package in Debian > Etch AMD64. > > As I'm new to postgresql I've googled to find some tips and found some > interesting links how configure and tune the database manager. Among > others I've found the PowerPostgresql pages with a performance checklist > and annotated guide to postgresql.conf > [http://www.powerpostgresql.com/]. And of course the postgresql site > itself is a good way to start. RevSys have a short guide as well > [http://www.revsys.com/writings/postgresql-performance.html] > > I just wonder if someone on this list have some tips from the real world > how to tune postgresql and what is to be avoided. AFAIK the following > parameters seems important to adjust to start with are: > > -work_mem > -maintenance_work_mem - 50% of the largest table? > -shared_buffers - max value 50000 > -effective_cache_size - max 2/3 of available ram, ie 24GB on the Do you use a Opteron with a NUMA architecture ? You could end up with switching pages between your memory nodes, which slowed down heavily my server (Tyan 2895, 2 x 275 cpu, 8 GB)... Try first to use only one numa node for your cache. > hardware described above > -shmmax - how large dare I set this value on dedicated postgres servers? > -checkpoint_segments - this is crucial as one of the server is > transaction heavy > -vacuum_cost_delay > > Of course some values can only be estimated after database has been feed > data and queries have been run in a production like manner. > > Cheers > // John > > Ps. I sent to list before but the messages where withheld as I'm not "a > member of any of the restrict_post groups". This is perhaps due to the > fact that we have changed email address a few weeks ago and there was a > mismatch between addresses. So I apologize if any similar messages show > up from me, just ignore them. > > ---------------------------(end of broadcast)--------------------------- > TIP 2: Don't 'kill -9' the postmaster
