Re: slow delete...

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От Jessica Richard
Тема Re: slow delete...
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Msg-id 310112.61618.qm@web56415.mail.re3.yahoo.com
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Ответ на slow delete...  (Jessica Richard <rjessil@yahoo.com>)
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thanks a lot. I imagine this will help me a lot. I will give it a try!!!

One more question: in the explain output, what is that "Bitmap Heap Scan on test"?, is it a bad thing (a table scan)? I would love to see the index scan instead of this Heap scan... what does "Heap Scan" actually do here?

 Bitmap Heap Scan on test  (cost=2110.49..10491.57 rows=79766 width=6)
   Recheck Cond: ((cola)::text = 'abc'::text)
   ->  Bitmap Index Scan on test_cola_idx  (cost=0.00..2090.55 rows=79766 width=0)
         Index Cond: ((cola)::text = 'abc'::text)
(4 rows)

Thanks again,
Jessica

----- Original Message ----
From: Charles Duffy <charles.duffy@gmail.com>
To: Jessica Richard <rjessil@yahoo.com>
Cc: pgsql-admin@postgresql.org
Sent: Friday, July 4, 2008 3:17:43 AM
Subject: Re: [ADMIN] slow delete...

> by the way, there is a foreign key on another table that references the
> primary key col0 on table test.
>

Try putting an index on the FK column in the other table. Analyse the
table. Test by starting a transaction then
issuing: explain analyze delete from test where cola = 'abc'. Should be faster.


Charles Duffy

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