On 01/25/2016 09:55 AM, Tom Smith wrote: > Thanks, the solution would work for fixed interval timestamp. > But the data I am dealing with has irregular timestamp so can not be > generated with exact steps. > > I would consider this a special case/method of random sampling, evenly > distributed sampling according to the defined timestamp index. You could probably create your own sampling method to do what you want. See contrib modules tsm_system_rows and tsm_system_time for guidance. http://www.postgresql.org/docs/current/static/tsm-system-rows.html http://www.postgresql.org/docs/current/static/tsm-system-time.html -- Vik Fearing +33 6 46 75 15 36 http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general