Re: PG 9..5 index performance Q's

-----Original Message-----
From: pgsql-admin-owner(at)postgresql(dot)org [mailto:pgsql-admin-owner(at)postgresql(dot)org] On Behalf Of ghiureai
Sent: Tuesday, November 08, 2016 1:31 PM
To: pgsql-admin(at)postgresql(dot)org
Subject: [ADMIN] PG 9..5 index performance Q's

Hi List,

running PGSQL 9.5.1 ( EL7) ,
we are seeing a issues with one of our SQL statement getting the wrong
plan once in a while ( large temp tables being generate, exec time
takes > 3 minutes compared with fastes plan < 1 min), we want to undestand why a new/ expensive plan is been used instead of efficient one, there are not data changes on the tables, any tips where to look?
Second , I would like to know if when re-creating one index ( non pk ) on a large table with already existing indexes, are All tables statistics being re-generated? ( there is a way to control persistency of old stats?)

Isabella

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Without seeing execution plans (both: fast and slow) it's hard to tell.
Auto_explain extension can help you catching these plans in PG log.
Your temp tables - are they being analyzed?

Regards,
Igor Neyman