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* LIKE search with ending % not optimized in v8
@ 2005-06-22 09:03 Aditya Damle <aditya@skillnetinc.com>
2005-06-28 05:16 ` Re: LIKE search with ending % not optimized in v8 Michael Fuhr <mike@fuhr.org>
0 siblings, 1 reply; 2+ messages in thread
From: Aditya Damle @ 2005-06-22 09:03 UTC (permalink / raw)
To: pgsql-performance
Hello. I believe in earlier versions, a query of the
form
select attrib from ttt where attrib like 'foo%' would
be able to take advantage of an index. I have seen
this in the past. Currently I am using v8.0.3. From
what I can see is that the execultion plan seems to
use a seq scan and to totally ignore the index. Is
this the case?
-Aditya
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: LIKE search with ending % not optimized in v8
2005-06-22 09:03 LIKE search with ending % not optimized in v8 Aditya Damle <aditya@skillnetinc.com>
@ 2005-06-28 05:16 ` Michael Fuhr <mike@fuhr.org>
0 siblings, 0 replies; 2+ messages in thread
From: Michael Fuhr @ 2005-06-28 05:16 UTC (permalink / raw)
To: Aditya Damle <aditya@skillnetinc.com>; +Cc: pgsql-performance
On Wed, Jun 22, 2005 at 02:03:29AM -0700, Aditya Damle wrote:
>
> Hello. I believe in earlier versions, a query of the
> form
> select attrib from ttt where attrib like 'foo%' would
> be able to take advantage of an index. I have seen
> this in the past. Currently I am using v8.0.3. From
> what I can see is that the execultion plan seems to
> use a seq scan and to totally ignore the index. Is
> this the case?
8.0.3 can certainly use indexes for LIKE queries, but the planner
will choose a sequential scan if it thinks that would be faster.
Have you vacuumed and analyzed your tables? Could you post the
EXPLAIN ANALYZE output of a query, once with enable_seqscan turned
on and once with it turned off?
See also "Operator Classes" in the "Indexes" chapter of the
documentation:
http://www.postgresql.org/docs/8.0/static/indexes-opclass.html
What locale are you using?
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/
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2005-06-22 09:03 LIKE search with ending % not optimized in v8 Aditya Damle <aditya@skillnetinc.com>
2005-06-28 05:16 ` Michael Fuhr <mike@fuhr.org>
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