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* DISTINCT Question
@ 2007-05-08 19:52 Y Sidhu <ysidhu@gmail.com>
0 siblings, 3 replies; 4+ messages in thread
From: Y Sidhu @ 2007-05-08 19:52 UTC (permalink / raw)
To: pgsql-performance
Does using DISTINCT in a query force PG to abandon any index search it might
have embarked upon?
--
Yudhvir Singh Sidhu
408 375 3134 cell
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: DISTINCT Question
@ 2007-05-08 19:55 Steinar H. Gunderson <sgunderson@bigfoot.com>
parent: Y Sidhu <ysidhu@gmail.com>
2 siblings, 0 replies; 4+ messages in thread
From: Steinar H. Gunderson @ 2007-05-08 19:55 UTC (permalink / raw)
To: Y Sidhu <ysidhu@gmail.com>; +Cc: pgsql-performance
On Tue, May 08, 2007 at 12:52:35PM -0700, Y Sidhu wrote:
> Does using DISTINCT in a query force PG to abandon any index search it might
> have embarked upon?
No.
If you need help with a specific query, please post it, along with your table
definitions and EXPLAIN ANALYZE output.
/* Steinar */
--
Homepage: http://www.sesse.net/
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: DISTINCT Question
@ 2007-05-08 19:57 Joshua D. Drake <jd@commandprompt.com>
parent: Y Sidhu <ysidhu@gmail.com>
2 siblings, 0 replies; 4+ messages in thread
From: Joshua D. Drake @ 2007-05-08 19:57 UTC (permalink / raw)
To: Y Sidhu <ysidhu@gmail.com>; +Cc: pgsql-performance
Y Sidhu wrote:
> Does using DISTINCT in a query force PG to abandon any index search it
> might have embarked upon?
Depends on the where clause.
>
> --
> Yudhvir Singh Sidhu
> 408 375 3134 cell
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^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: DISTINCT Question
@ 2007-05-08 20:28 Scott Marlowe <smarlowe@g2switchworks.com>
parent: Y Sidhu <ysidhu@gmail.com>
2 siblings, 0 replies; 4+ messages in thread
From: Scott Marlowe @ 2007-05-08 20:28 UTC (permalink / raw)
To: Y Sidhu <ysidhu@gmail.com>; +Cc: pgsql-performance
On Tue, 2007-05-08 at 14:52, Y Sidhu wrote:
> Does using DISTINCT in a query force PG to abandon any index search it
> might have embarked upon?
explain analyze select distinct request from businessrequestsummary
where lastflushtime between now() - interval '30 minutes' and now();
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Unique (cost=3.04..3.04 rows=1 width=17) (actual time=110.565..162.630
rows=75 loops=1)
-> Sort (cost=3.04..3.04 rows=1 width=17) (actual
time=110.555..135.252 rows=6803 loops=1)
Sort Key: request
-> Index Scan using businessrequestsummary_lastflushtime_dx on
businessrequestsummary (cost=0.01..3.03 rows=1 width=17) (actual
time=0.063..59.674 rows=6803 loops=1)
Index Cond: ((lastflushtime >= (now() -
'00:30:00'::interval)) AND (lastflushtime <= now()))
Total runtime: 163.925 ms
(6 rows)
I'd say no.
^ permalink raw reply [nested|flat] 4+ messages in thread
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-- links below jump to the message on this page --
2007-05-08 19:52 DISTINCT Question Y Sidhu <ysidhu@gmail.com>
2007-05-08 19:55 ` Steinar H. Gunderson <sgunderson@bigfoot.com>
2007-05-08 19:57 ` Joshua D. Drake <jd@commandprompt.com>
2007-05-08 20:28 ` Scott Marlowe <smarlowe@g2switchworks.com>
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