On 17.3.2015 15:19, Thomas Kellerer wrote: > 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.
How do you get the last record (with respect to a timestamp column) using a DISTINCT ON? -- Tomas Vondra http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
