>> rhaas=# explain select a from generate_series(1,100) a union select a >> from generate_series(1,100) a; >> QUERY PLAN >> -------------------------------------------------------------------------------------- >> HashAggregate (cost=45.00..65.00 rows=2000 width=4) >> -> Append (cost=0.00..40.00 rows=2000 width=4) Why in this case the estimated number of rows is 2000? Is it standard planner behavior? -- View this message in context: http://postgresql.1045698.n5.nabble.com/UNION-and-bad-performance-tp3301375p5806445.html Sent from the PostgreSQL - performance mailing list archive at Nabble.com.
