On Thu, 2010-08-12 at 11:59 +0530, Ma Sivakumar wrote: > What does a migrating PHP/MySQL user do? If MySQL performs fast just > out of box (I have not used MySQL), what is different there? Do MySQL > defaults give better performance? How do they arrive at those > defaults? I have been watching this thread off and on and I think this is the question that many are kind of ignoring. With deepest respect to Greg Smith who frankly knows more about intricacies PostgreSQL performance than I would ever care to, I think he is looking at this wrong. "Can we just say in the docs say 25% of memory to shared_buffers" Yes, in fact we can. With the caveat of Windows, the reality is this isn't going to hurt nearly as much as a untuned version of PostgreSQL will. Now work_mem is an entirely different issue. Frankly it doesn't need to be changed, even from the default. *IF* you spill over it will be on specific larger queries that you can then tune. We should and can put in the docs a table that says: GOOD PERFORMANCE IS ALWAYS RELIANT ON PROPER HARDWARE, DATABASE DESIGN AND APPLICATION ARCHITECTURE. THIS TABLE IS A HINT ONLY. YOU WILL LIKELY HAVE TO TUNE BEYOND THIS. shared_buffers = 25% of available memory work_mem = 2-4MB (test using explain analyze) effective_cache_size = 50-60% of available memory INCLUDING shared_buffers etc.... Joshua D. Drake -- PostgreSQL.org Major Contributor Command Prompt, Inc: http://www.commandprompt.com/ - 509.416.6579 Consulting, Training, Support, Custom Development, Engineering http://twitter.com/cmdpromptinc | http://identi.ca/commandprompt -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
