| From: | "Tomas Vondra" <tv(at)fuzzy(dot)cz> |
|---|---|
| To: | "Jayadevan M" <Jayadevan(dot)Maymala(at)ibsplc(dot)com> |
| Cc: | "Heikki Linnakangas" <heikki(dot)linnakangas(at)enterprisedb(dot)com>, "PGSQL Performance" <pgsql-performance(at)postgresql(dot)org>, pgsql-performance-owner(at)postgresql(dot)org |
| Subject: | Re: Query performance issue |
| Date: | 2011-08-31 11:41:55 |
| Message-ID: | 30d4c8e39eef1ff30337242b4dedfd34.squirrel@sq.gransy.com |
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| Thread: | |
| Lists: | pgsql-performance |
On 31 Srpen 2011, 13:19, Jayadevan M wrote:
> Hello,
>
>> >
>> > Please run EXPLAIN ANALYZE on the query and post that, it's hard to
> say
>> > what's wrong from just the query plan, without knowing where the time
> is
>> > actually spent.
>> Here is the explain analyze
>> http://explain.depesz.com/s/MY1
> Going through the url tells me that statistics may be off. I will try
> analyzing the tables. That should help?
> Regards,
> Jayadevan
That could help, but not necessarily.
A really interesting part is the sort near the bottom -
-> Sort (cost=1895.95..1896.49 rows=215 width=61) (actual
time=25.926..711784.723 rows=2673340321 loops=1)
Sort Key: memmst.memshpsta
Sort Method: quicksort Memory: 206kB
-> Nested Loop (cost=0.01..1887.62 rows=215 width=61) (actual
time=0.088..23.445 rows=1121 loops=1)
How can a sort ge 1121 rows at the input and return 2673340321 rows at the
output? Not sure where this comes from.
BTW what PostgreSQL version is this?
Tomas
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