"Logan Bowers" <logan@xxxxxxxxxx> writes: > I'm potentially having a strange performance problem. I have a BIG > table: ~100M, ~1KB rows. I do a SELECT count(*) from it (I know it will > be slow) and as I watch procinfo on my DB server I see a huge amount of > write activity. Thus, > 1) Why does this statement generate any writes at all? It could be that it's evicting unrelated dirty pages from cache (although PG 8.0 is supposed to try to avoid doing that during a simple seqscan). Another theory is that the table has a whole lot of recently-changed rows, and the writes are a side effect of the SELECT setting commit hint bits to tell future transactions what it found out about the commit status of the rows. I dunno what procinfo is --- personally I would use strace and see exactly which file(s) the database processes are issuing writes against. Also check whether a second SELECT against the same table continues to issue writes... regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
