I know PG 10 will have support "CREATE STATISTICS.." for this.. ..but I wondered if there's a recommended workaround in earlier versions ?
We had two issues: 1) improper estimate caused poor plans (nested loops due to ::date, GROUP BY, cross-column stats, and maybe more). 2) memory explosion in hash join (due to poor estimate?) caused OOM. I tried ROW/ARRAY comparison for the correlated columns which seems to do what I want, acting as a single comparison, rather than two, independent comparisons. -> Merge Join (cost=57811.81..62290.04 rows=114606 width=58) (actual time=5174.556..5698.323 rows=204672 loops=1) Merge Cond: ((eric_enodeb_cellrelation_metrics.start_time = eric_enodeb_cellrelation_metrics_1.start_time) AND ((ROW(eric_enodeb_cellrelation_metrics.sect_id, eric_enodeb_cellrelation_metrics.neigh_sect_id)) = (ROW(eric_enodeb_cellrelation_metrics_1.neigh_sect_id, eric_enodeb_cellrelation_metrics_1.sect_id)))) Thanks, Justin -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
