Jeff Janes <jeff.janes@xxxxxxxxx> writes: > I think the next step would be to run gdb -p <pid> (but don't start > gdb until backend is in the middle of a slow explain), then: Sorry, I am lack debug symbols, so call trace is incomplete: explain select i.item_id, u.user_id from items i left join users u on u.user_id = i.user_id where item_id = 169946840 #0 0x00007ff766967620 in read () from /lib/libc.so.6 #1 0x00007ff7689cfc25 in FileRead () #2 0x00007ff7689ea2f6 in mdread () #3 0x00007ff7689cc473 in ?? () #4 0x00007ff7689ccf54 in ReadBufferExtended () #5 0x00007ff7688050ca in index_fetch_heap () #6 0x00007ff76880523e in index_getnext () #7 0x00007ff768a63306 in ?? () #8 0x00007ff768a67624 in ?? () #9 0x00007ff768a67d9c in ?? () #10 0x00007ff768a68376 in mergejoinscansel () #11 0x00007ff76896faa6 in initial_cost_mergejoin () #12 0x00007ff768977695 in ?? () #13 0x00007ff76897816c in add_paths_to_joinrel () #14 0x00007ff76897981b in make_join_rel () #15 0x00007ff768979ac9 in join_search_one_level () #16 0x00007ff76896a3ab in standard_join_search () #17 0x00007ff7689837c1 in query_planner () #18 0x00007ff768985260 in ?? () #19 0x00007ff7689870a9 in subquery_planner () #20 0x00007ff76898736e in standard_planner () #21 0x00007ff7689ef3ce in pg_plan_query () #22 0x00007ff7688c94a3 in ?? () #23 0x00007ff7688c9809 in ExplainQuery () #24 0x00007ff7648095e2 in ?? () from /usr/lib/postgresql/9.2/lib/pg_stat_statements.so #25 0x00007ff7689f1f27 in ?? () #26 0x00007ff7689f3295 in ?? () #27 0x00007ff7689f388f in PortalRun () #28 0x00007ff7689ef96d in ?? () #29 0x00007ff7689f0950 in PostgresMain () #30 0x00007ff7689aa7a3 in ?? () #31 0x00007ff7689ad73c in PostmasterMain () #32 0x00007ff768948e4b in main () #0 0x00007ff766973950 in lseek64 () from /lib/libc.so.6 #1 0x00007ff7689cf88d in FileSeek () #2 0x00007ff7689ea09c in mdwrite () #3 0x00007ff7689cb12f in ?? () #4 0x00007ff7689cca43 in ?? () #5 0x00007ff7689ccf54 in ReadBufferExtended () #6 0x00007ff7688050ca in index_fetch_heap () #7 0x00007ff76880523e in index_getnext () #8 0x00007ff768a63306 in ?? () #9 0x00007ff768a67624 in ?? () #10 0x00007ff768a67d9c in ?? () #11 0x00007ff768a68376 in mergejoinscansel () #12 0x00007ff76896faa6 in initial_cost_mergejoin () #13 0x00007ff768977695 in ?? () #14 0x00007ff76897816c in add_paths_to_joinrel () #15 0x00007ff76897981b in make_join_rel () #16 0x00007ff768979ac9 in join_search_one_level () #17 0x00007ff76896a3ab in standard_join_search () #18 0x00007ff7689837c1 in query_planner () #19 0x00007ff768985260 in ?? () #20 0x00007ff7689870a9 in subquery_planner () #21 0x00007ff76898736e in standard_planner () #22 0x00007ff7689ef3ce in pg_plan_query () #23 0x00007ff7688c94a3 in ?? () #24 0x00007ff7688c9809 in ExplainQuery () #25 0x00007ff7648095e2 in ?? () from /usr/lib/postgresql/9.2/lib/pg_stat_statements.so #26 0x00007ff7689f1f27 in ?? () #27 0x00007ff7689f3295 in ?? () #28 0x00007ff7689f388f in PortalRun () #29 0x00007ff7689ef96d in ?? () #30 0x00007ff7689f0950 in PostgresMain () #31 0x00007ff7689aa7a3 in ?? () #32 0x00007ff7689ad73c in PostmasterMain () #33 0x00007ff768948e4b in main () #0 0x00007ff766973950 in lseek64 () from /lib/libc.so.6 #1 0x00007ff7689cf88d in FileSeek () #2 0x00007ff7689ea2b9 in mdread () #3 0x00007ff7689cc473 in ?? () #4 0x00007ff7689ccf54 in ReadBufferExtended () #5 0x00007ff7688050ca in index_fetch_heap () #6 0x00007ff76880523e in index_getnext () #7 0x00007ff768a63306 in ?? () #8 0x00007ff768a67624 in ?? () #9 0x00007ff768a67d9c in ?? () #10 0x00007ff768a68376 in mergejoinscansel () #11 0x00007ff76896faa6 in initial_cost_mergejoin () #12 0x00007ff768977695 in ?? () #13 0x00007ff76897816c in add_paths_to_joinrel () #14 0x00007ff76897981b in make_join_rel () #15 0x00007ff768979ac9 in join_search_one_level () #16 0x00007ff76896a3ab in standard_join_search () #17 0x00007ff7689837c1 in query_planner () #18 0x00007ff768985260 in ?? () #19 0x00007ff7689870a9 in subquery_planner () #20 0x00007ff76898736e in standard_planner () #21 0x00007ff7689ef3ce in pg_plan_query () #22 0x00007ff7688c94a3 in ?? () #23 0x00007ff7688c9809 in ExplainQuery () #24 0x00007ff7648095e2 in ?? () from /usr/lib/postgresql/9.2/lib/pg_stat_statements.so #25 0x00007ff7689f1f27 in ?? () #26 0x00007ff7689f3295 in ?? () #27 0x00007ff7689f388f in PortalRun () #28 0x00007ff7689ef96d in ?? () #29 0x00007ff7689f0950 in PostgresMain () #30 0x00007ff7689aa7a3 in ?? () #31 0x00007ff7689ad73c in PostmasterMain () #32 0x00007ff768948e4b in main () -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
