> > CREATE STATISTICS st_simrun_component_metadata (dependencies) ON > sim_run_id, key FROM sim_run_component_metadata; > ANALYZE sim_run_component_metadata; > > When I run this query, no statistics are returned: > > SELECT m.* FROM pg_statistic_ext join pg_statistic_ext_data on (oid = > stxoid), > > pg_mcv_list_items(stxdmcv) m WHERE stxname = > 'st_simrun_component_metadata'; > > Is there something I might have missed? >
It looks like you created "dependencies" statistics, but then searched for "mcv" statistics. To test if mcv helps, you could drop and recreate as: CREATE STATISTICS st_simrun_component_metadata (mcv) ... The fetch from the table is rather fast. some milliseconds. But a > subsequent sort operations takes very long time, for the amount of records > fetched. > This does not seem to be the case for the slow cases you shared (those are dominated by several millisecond index scans that are looped over 32k times). So I assume you're talking about the fast case? If so, there is a Sort that takes a couple of hundred milliseconds being done on disk (~15MB) so you might also want to look into how fast that would be in memory (via work_mem). > But, just like the estimated rows in the plan, it does not match the real > amount of available data in the table: > I'm not sure what you mean by this, is it only that the row estimates are still bad? Regards, Michael
