Postgres Pro
Downloads
Home   >   mailing lists

Re: Slow query + why bitmap index scan?? - Mailing list pgsql-performance

From Florian Weimer
Subject Re: Slow query + why bitmap index scan??
Date
Msg-id 82y66qp7al.fsf@mid.bfk.de
Whole thread Raw
In response to Slow query + why bitmap index scan??  (Laszlo Nagy <gandalf@shopzeus.com>)
Responses Re: Slow query + why bitmap index scan??  (Laszlo Nagy <gandalf@shopzeus.com>)
List pgsql-performance
Tree view 
* Laszlo Nagy:

> This query:
>
> select hid from product_price_history where id=35547581
>
> Returns 759 rows in 8837 msec! How can this be that slow???

If most records are on different heap pages, processing this query
requires many seeks.  11ms per seek is not too bad if most of them are
cache misses.

--
Florian Weimer                <fweimer@bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99

pgsql-performance by date:

Previous
From: Laszlo Nagy
Date:
Subject: Slow query + why bitmap index scan??
Next
From: Mladen Gogala
Date:
Subject: The good, old times