Thread: Calculating memory allocaiton per process
Howdy, Is there a doc somewhere that has a formula for how much memory PG backend process will use? I'm looking to get something like total_mem = max_connections * ( work_mem + temp_buffers ) // I know it's more complicated than that, which is why I'm asking =) Something similar to Table 17-2 here: http://www.postgresql.org/docs/9.0/interactive/kernel-resources.html would be awesome. Dave
David Kerr <dmk@mr-paradox.net> writes: > Howdy, > > Is there a doc somewhere that has a formula for how much memory PG > backend process will use? > > I'm looking to get something like total_mem = max_connections * ( > work_mem + temp_buffers ) // I know it's more complicated than that, > which is why I'm asking =) Depends on your query complexity, load distribution across concurrent sessions and session lifetime. work_mem will, in cases of queries having multiple sort nodes, have to be counted multiple times on behalf of a single backend. Some observation of the running system can be your best bet. HTH > Something similar to Table 17-2 here: > http://www.postgresql.org/docs/9.0/interactive/kernel-resources.html > would be awesome. > > Dave -- Jerry Sievers Postgres DBA/Development Consulting e: gsievers19@comcast.net p: 305.321.1144
On Thu, Apr 14, 2011 at 03:00:07PM -0400, Jerry Sievers wrote: - David Kerr <dmk@mr-paradox.net> writes: - - > Howdy, - > - > Is there a doc somewhere that has a formula for how much memory PG - > backend process will use? - > - > I'm looking to get something like total_mem = max_connections * ( - > work_mem + temp_buffers ) // I know it's more complicated than that, - > which is why I'm asking =) - - Depends on your query complexity, load distribution across concurrent - sessions and session lifetime. - - work_mem will, in cases of queries having multiple sort nodes, have to - be counted multiple times on behalf of a single backend. - - Some observation of the running system can be your best bet. - - HTH Yeah, that's the complication that I knew about (but am still not able to fully 'get', let along vocalize). Are there no rules of thumb or upper bounds to help estimate total memory usage? Thanks Dave