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* SELECT performance problem
@ 2007-02-20 23:21 Glenn Sullivan <glenn.sullivan@varianinc.com>
0 siblings, 2 replies; 3+ messages in thread
From: Glenn Sullivan @ 2007-02-20 23:21 UTC (permalink / raw)
To: pgsql-performance
I am updating from 7.4.5 to 8.2.3. I have noticed a significant
slowdown in simple searches such as
"select filename from vnmr_data where seqfil = 'sems';"
This returns 12 rows out of 1 million items in the table.
On 7.4.5, this takes about 1.5 seconds. On 8.2.3, it is taking
about 9 seconds.
I have played with different values of:
work_mem, temp_buffers, shared_buffers and effective_cache_size
and none of them make any difference.
I am running on redhat Linux 4 64bit.
Any ideas?
Glenn
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: SELECT performance problem
@ 2007-02-20 23:41 Jeff Frost <jeff@frostconsultingllc.com>
parent: Glenn Sullivan <glenn.sullivan@varianinc.com>
1 sibling, 0 replies; 3+ messages in thread
From: Jeff Frost @ 2007-02-20 23:41 UTC (permalink / raw)
To: Glenn Sullivan <glenn.sullivan@varianinc.com>; +Cc: pgsql-performance
On Tue, 20 Feb 2007, Glenn Sullivan wrote:
> I am updating from 7.4.5 to 8.2.3. I have noticed a significant
> slowdown in simple searches such as
> "select filename from vnmr_data where seqfil = 'sems';"
> This returns 12 rows out of 1 million items in the table.
> On 7.4.5, this takes about 1.5 seconds. On 8.2.3, it is taking
> about 9 seconds.
>
> I have played with different values of:
> work_mem, temp_buffers, shared_buffers and effective_cache_size
> and none of them make any difference.
>
> I am running on redhat Linux 4 64bit.
Glenn,
Can you forward us the explain analyze output from 7.4.5 and 8.2.3 for the
query in question?
Also, is the hardware the same between 7.4.5 and 8.2.3? If not, what is the
difference?
--
Jeff Frost, Owner <jeff@frostconsultingllc.com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: SELECT performance problem
@ 2007-02-20 23:46 Dave Dutcher <dave@tridecap.com>
parent: Glenn Sullivan <glenn.sullivan@varianinc.com>
1 sibling, 0 replies; 3+ messages in thread
From: Dave Dutcher @ 2007-02-20 23:46 UTC (permalink / raw)
To: 'Glenn Sullivan' <glenn.sullivan@varianinc.com>; pgsql-performance
Did you run ANALYZE on your data after importing it into 8.2.3? Is there an
index on the seqfil column? If so, you should post the output of EXPLAIN
ANALYZE from both systems if possible.
> -----Original Message-----
> From: pgsql-performance-owner@postgresql.org
> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of
> Glenn Sullivan
> Sent: Tuesday, February 20, 2007 5:22 PM
> To: pgsql-performance@postgresql.org
> Subject: [PERFORM] SELECT performance problem
>
>
> I am updating from 7.4.5 to 8.2.3. I have noticed a significant
> slowdown in simple searches such as
> "select filename from vnmr_data where seqfil = 'sems';"
> This returns 12 rows out of 1 million items in the table.
> On 7.4.5, this takes about 1.5 seconds. On 8.2.3, it is taking
> about 9 seconds.
>
> I have played with different values of:
> work_mem, temp_buffers, shared_buffers and effective_cache_size
> and none of them make any difference.
>
> I am running on redhat Linux 4 64bit.
>
> Any ideas?
>
> Glenn
>
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^ permalink raw reply [nested|flat] 3+ messages in thread
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Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2007-02-20 23:21 SELECT performance problem Glenn Sullivan <glenn.sullivan@varianinc.com>
2007-02-20 23:41 ` Jeff Frost <jeff@frostconsultingllc.com>
2007-02-20 23:46 ` Dave Dutcher <dave@tridecap.com>
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