Re: Query performance

On Thu, Jun 13, 2013 at 12:49 AM, K P Manoj <kpmanojpg(at)gmail(dot)com> wrote:
> One of my query treating performance issue on my production server.
> Once i run query on my parent table with specific condition(hard coded
> value) its uses only proper child table and its index on explain plan ,
> but once i am using table conditions (instead of hard coded value), query
> planner is going all the child tables, Can i know where i am worng

From the docs:

"Constraint exclusion only works when the query's WHERE clause
contains constants (or externally supplied parameters). For example, a
comparison against a non-immutable function such as CURRENT_TIMESTAMP
cannot be optimized, since the planner cannot know which partition the
function value might fall into at run time."

http://www.postgresql.org/docs/9.2/static/ddl-partitioning.html#DDL-PARTITIONING-CAVEATS

--
Kind regards,
Sergey Konoplev
PostgreSQL Consultant and DBA

Profile: http://www.linkedin.com/in/grayhemp
Phone: USA +1 (415) 867-9984, Russia +7 (901) 903-0499, +7 (988) 888-1979
Skype: gray-hemp
Jabber: gray(dot)ru(at)gmail(dot)com