Kevin Grittner wrote: > Alvaro Herrera <alvherre@xxxxxxxxxxxxxxxxx> wrote: > > Actually, a transaction that performed no writes doesn't get a > > commit WAL record written, so it shouldn't make any difference at > > all. > > Well, concurrent to the web application is the replication. Would > asynchronous commit of that potentially alter the pattern of writes > such that it had less impact on the reads? Well, certainly async commit would completely change the pattern of writes: it would give the controller an opportunity to reorder them according to some scheduler. Otherwise they are strictly serialized. > I'm thinking, again, of > why the placement of the pg_xlog on a separate file system made such > a dramatic difference to the read-only response time -- might it > make less difference if the replication was using asynchronous > commit? Yeah, I think it would have been less notorious, but this is all theoretical. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
