Do EXPLAIN ANALYZE: . . . only showing the bottom node . . . -> Seq Scan on YYYYY (cost=0.00..37962.29 rows=876029 width=40) (actual time=16.728..92555.945 rows=876002 loops=1) Output: foo, bar Buffers: shared hit=146 read=29056 written=2325 !!!!! "Total runtime: 375542.347 ms" Then Do EXPLAIN ANALYZE again: . . . only showing the bottom node . . . -> Seq Scan on YYYYY (cost=0.00..37962.29 rows=876029 width=40) (actual time=0.192..2972.127 rows=876002 loops=1) Output: foo, bar Buffers: shared hit=210 read=28992 "Total runtime: 32913.884 ms" In general, can you tell me why [written=2325] is displayed by the first EXPLAIN, but not the second EXPLAIN ? The query is a SELECT, so what is getting "written" ? Note that both EXPLAINs have the exact same plan. Bottom up is: Seq Scan on YYYY, Hash, Seq Scan on XXXX, Hash Join, HashAggregate I am wondering if it is a clue as to why the "actual time" is so different from one run to the next. The query is 2 tables joined, with a group by: select sum (case when X.hid is null and not Y.cntr = '0' then 1 else 0 end) as colp from xxxxx X inner join yyyyy Y on Y.coln = X.colm where X.some_id = 'aeiou' group by X.some_type Thanks, -dvs- -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
