On Mon, 7 Jan 2019 at 21:40, Mitar <mmitar@xxxxxxxxx> wrote: > > On Mon, Jan 7, 2019 at 12:09 AM David Rowley > <david.rowley@xxxxxxxxxxxxxxx> wrote: > > On Mon, 7 Jan 2019 at 18:54, Mitar <mmitar@xxxxxxxxx> wrote: > > > If I have a PREPAREd query without parameters (static) and I EXECUTE > > > it repeatedly in the same session, does PostgreSQL learn/optimize > > > anything across those runs? > > > > Yes, it will generate the query plan on the first invocation of > > EXECUTE and use that plan for all subsequent EXECUTEs for the session > > until you DEALLOCATE the prepared query or DISCARD PLANS/ALL; > > So this sounds more like no? So the same plan is used, so PostgreSQL > is not further optimizing the plan based on any statistics or > anything? You asked if it learned anything. I mentioned that it learns the query plan, so I'd have said "Yes". If you're asking if it caches the result and foregoes scanning the underlying tables, then that's a "No". Else what further optimising did you have in mind? -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
