I'm not sure what "unusually large" is, but they're all < 1mb which is a little larger than some of our other comparable databases (mostly <300kb) but seems reasonable to me. Regards, David On 4/11/19, 3:37 pm, "Laurenz Albe" <laurenz.albe@xxxxxxxxxxx> wrote: On Mon, 2019-11-04 at 03:04 +0000, David Wheeler wrote: > We’re having trouble working out why the planning time for this particular query is slow > (~2.5s vs 0.9ms execution time). As you can see below, there are only 3 tables involved > so it’s hard to imagine what decisions the planner has to make that take so long. After > 5 runs the prepared-statement code kicks in and it becomes quick, but it’s quite > infuriating for the first 5 runs given the execution is so much faster. > > Are you able to give any tips what might be taking so long (and how we might improve it)? > [...] > Planning time: 2429.682 ms > > Execution time: 0.914 ms Strange. Are any of your catalog tables unusually large? SELECT pg_relation_size(t.oid), t.relname FROM pg_class AS t JOIN pg_namespace AS n ON t.relnamespace = n.oid WHERE t.relkind = 'r' ORDER BY pg_relation_size(t.oid) DESC LIMIT 10; Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com