explain select ss, ARRAY(select id from foo where ss>0 and id between 7 and 156 order by random() limit 3) as v from generate_series(1,1000000) ss; QUERY PLAN ------------------------------------------------------------------------------------ Function Scan on generate_series ss (cost=0.00..9381.22 rows=1000 width=4) SubPlan -> Limit (cost=9.36..9.37 rows=3 width=8) -> Sort (cost=9.36..9.74 rows=150 width=8) Sort Key: (random()) -> Result (cost=0.00..7.42 rows=150 width=8) One-Time Filter: ($0 > 0) -> Seq Scan on foo (cost=0.00..7.05 rows=150 width=8) Filter: ((id >= 7) AND (id <= 156)) (9 rows) :( no matter if I change last generate_series's range, it will always estimate 1000 rows... -- GJ -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance