Re: Delete followed by Select Count(1)

From: Deepak Thapliyal <deepakthapliyal_at_yahoo.com>
Date: Thu, 16 Aug 2001 18:12:31 -0700
Message-ID: <F001.0036E4F5.20010816181533@fatcity.com>

Hi Jonathan,

Can you tell us a little bit more about delayed block cleanouts .. if you can

Thx
Deepak
--- Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk> wrote:
> Apart from the comments other posters
> have made about truncate and the HWM,
> bear in mind that a scan after deleting 100,000
> rows would probably be doing a lot of
> delayed block cleanout - resulting in plenty
> of redo log, and possibly a lot of dbwr activity.
>
> Jonathan Lewis
>
> Seminars on getting the best out of Oracle
> Last few places available for Sept 10th/11th
> See http://www.jlcomp.demon.co.uk/seminar.html
>
>
>
>
> -----Original Message-----
> To: Multiple recipients of list ORACLE-L
> <ORACLE-L_at_fatcity.com>
> Date: 16 August 2001 21:46
>
>
> |I have a user that deleted all of the rows in a
> table
> |(i.e. 100,000), waited for it to complete, and then
> |ran a SELECT COUNT(1) FROM <table>. It took a few
> |minutes for '0 rows' to be returned to the prompt.
> The
> |table has ~60 extents (128k ea.). Granted, the
> number
> |of extents is excessive but it's a development
> |instance and this table is an exception.
> |
>
>
> --
> Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> --
> Author: Jonathan Lewis
> INET: jonathan_at_jlcomp.demon.co.uk
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Deepak Thapliyal
  INET: deepakthapliyal_at_yahoo.com

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Received on Thu Aug 16 2001 - 20:12:31 CDT

Re: Delete followed by Select Count(1) - SLOW