On Tue, Jan 31, 2012 at 10:46 AM, Josh Berkus <josh@xxxxxxxxxxxx> wrote: > >> Shared buffers is the cache maintained by PostgreSQL. All all the data >> that you read/write need to go through shared buffers. > > While this is technically true, I need to point out that you generally > increase shared_buffers for high concurrency, and for reads, not for > writes, especially for row-at-a-time inserts. There's just not that > much memory required (although more than the out-of-the-box defaults). When inserting rows in bulk (even just with inserts in a tight loop) into indexed tables, I often see the performance collapse soon after the active index size exceeds shared_buffers. Or at least, shared_buffers + however much dirty data the kernel is willing to tolerate. But that later value is hard to predict. Increasing the shared_buffers can really help a lot here. I'm sure this behavior depends greatly on your IO subsystem. Cheers, Jeff -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
