Horton

Re: Various performance questions

Shridhar Daithankar <shridhar_daithankar@persistent.co.in>

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From: Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
To: Dror Matalon <dror@zapatec.com>
Cc: pgsql-performance@postgresql.org
Date: 2003-10-27T07:22:27Z
Lists: pgsql-performance 
Dror Matalon wrote:

> On Mon, Oct 27, 2003 at 01:04:49AM -0500, Christopher Browne wrote:
>>Most of the time involves:
>>
>> a) Reading each page of the table, and
>> b) Figuring out which records on those pages are still "live."
> 
> 
> The table has been VACUUM ANALYZED so that there are no "dead" records.
> It's still not clear why select count() would be slower than select with
> a "where" clause.

Do a vacuum verbose full and then everything should be within small range of 
each other.

Also in the where clause, does explicitly typecasting helps?

Like 'where channel<5000::int2;'

  HTH

  Shridhar