[PERFORM] work-mem how do I identify the proper size

2007-01-28 Thread Campbell, Lance
If I set work-mem at a particular amount of memory how do I answer the following questions: 1) How many of my queries were able to run inside the memory I allocated for work-mem? 2) How many of my queries had to run from disk because work-mem was not set high enough? 3) If a

Re: [PERFORM] Tuning

2007-01-28 Thread Tom Lane
Josh Berkus writes: >> -checkpoint_segments - this is crucial as one of the server is >> transaction heavy > Well, it only helps you to raise this if you have a dedicated disk resource > for the xlog. Otherwise having more segments doesn't help you much. Au contraire, large checkpoint_segment

Re: [PERFORM] Tuning

2007-01-28 Thread Josh Berkus
John, > -work_mem Depends on the number of concurrent queries you expect to run and what size sorts you expect them to do. > -maintenance_work_mem - 50% of the largest table? Actually, in current code I've found that anything over 256mb doesn't actually get used. > -shared_buffers - max valu

Re: [PERFORM] work_mem

2007-01-28 Thread Bill Moran
"Campbell, Lance" <[EMAIL PROTECTED]> wrote: > > I have been researching how to improve my overall performance of > postgres. I am a little confused on the reasoning for how work_mem is > used in the postgresql.conf file. The way I understand the > documentation is you define with work_mem how mu

Re: [PERFORM] work-mem

2007-01-28 Thread imad
work-mem tells the size of physical memory only, virtual memory is always there off course in case you run out of available memory. I recommend you reading PostgreSQL internals for all this stuff: http://www.postgresql.org/docs/8.0/static/internals.html --Imad www.EnterpriseDB.com On 1/29/07, C

[PERFORM] work-mem

2007-01-28 Thread Campbell, Lance
I have been researching how to improve my overall performance of postgres. I am a little confused on the reasoning for how work-mem is used in the postgresql.conf file. The way I understand the documentation is you define with work-mem how much memory you want to allocate per search. Couldn't yo

Re: [PERFORM] Bad Row Count Estimate on View with 8.2

2007-01-28 Thread Tom Lane
"Dave Dutcher" <[EMAIL PROTECTED]> writes: > Thanks for looking into it. I thought I might actually test if it was the > patch you mentioned which changed my results, but I haven't had time. > Because you mentioned it was grouping on the results of a UNION ALL which > was throwing off the row esti

Re: [PERFORM] Bad Row Count Estimate on View with 8.2

2007-01-28 Thread Dave Dutcher
> From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Tom Lane > > > In fact, since there isn't any "parent relation" in a UNION, I'm not > sure that this patch actually changed your results ... but I'm not > seeing what else would've ... > Thanks for looking into it. I thought I