Tomas Vondra schrieb am 17.03.2015 um 14:55: > (2) using window functions, e.g. like this: > > SELECT * FROM ( > SELECT *, > ROW_NUMBER() OVER (PARTITION BY touchpoint_execution_id > ORDER BY FROM max_creation_dt) AS rn > FROM s_f_touchpoint_execution_status_history > ) foo WHERE rn = 1 > > But estimating this is also rather difficult ...
>From my experience rewriting something like the above using DISTINCT ON is >usually faster. e.g.: select distinct on (touchpoint_execution_id) * from s_f_touchpoint_execution_status_history order by touchpoint_execution_id, max_creation_dt; -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
