Re: Why is PostgreSQL 9.1 not using index for simple equality select - Mailing list pgsql-general

From Yang Zhang
Subject Re: Why is PostgreSQL 9.1 not using index for simple equality select
Date
Msg-id CAKxBDU-vqLkpeL95ga4MrVG6f-0oyQT91e1G_MgMtmUe-jp-kg@mail.gmail.com
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In response to Re: Why is PostgreSQL 9.1 not using index for simple equality select  (John R Pierce <pierce@hogranch.com>)
Responses Re: Why is PostgreSQL 9.1 not using index for simple equality select
Re: Why is PostgreSQL 9.1 not using index for simple equality select
List pgsql-general
Doesn't seem to be the case.  This table has been around for a while
and should have been auto-analyzed by now.  But anyway:

db=> analyze lead;
ANALYZE
db=> explain select * from lead where email = 'foo@blah.com';
                                QUERY PLAN
---------------------------------------------------------------------------
 Seq Scan on lead  (cost=10000000000.00..10000319666.99 rows=1 width=5208)
   Filter: (email = 'foo@blah.com'::text)
(2 rows)

On Fri, Apr 12, 2013 at 1:13 AM, John R Pierce <pierce@hogranch.com> wrote:
> On 4/12/2013 1:03 AM, Yang Zhang wrote:
>>
>>      db=> explain select * from lead where email = 'blah';
>>                               QUERY PLAN
>>      ------------------------------------------------------------
>>       Seq Scan on lead  (cost=0.00..319599.38 rows=1 width=5108)
>>         Filter: (email = 'blah'::text)
>
>
>
> try EXPLAIN ANALYZE .....    its more useful.
>
> my guess is, there's no statistics on this table, and doing an ANALYZE lead;
> would rectify this.
>
>
>
> --
> john r pierce                                      37N 122W
> somewhere on the middle of the left coast
>
>
>
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--
Yang Zhang
http://yz.mit.edu/


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