| From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, <vjoshi(at)zetainteractive(dot)com>, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, Varadharajan Mukundan <srinathsmn(at)gmail(dot)com> |
| Cc: | <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Performance issues |
| Date: | 2015-03-16 19:43:46 |
| Message-ID: | 55073272.20209@BlueTreble.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On 3/13/15 7:12 PM, Tomas Vondra wrote:
> (4) I suspect many of the relations referenced in the views are not
> actually needed in the query, i.e. the join is performed but
> then it's just discarded because those columns are not used.
> Try to simplify the views as much has possible - remove all the
> tables that are not really necessary to run the query. If two
> queries need different tables, maybe defining two views is
> a better approach.
A better alternative with multi-purpose views is to use an outer join
instead of an inner join. With an outer join if you ultimately don't
refer to any of the columns in a particular table Postgres will remove
the table from the query completely.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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