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

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.
|

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Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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