Re: unused blocks BELOW HWM

Gene Gurevich wrote:
>
> Hi all:
>
> Is there a way for me to see how many blocks under
> the HWM are unused?
>
> thanks
>
> Gene
>
> =====

I once wrote something which was querying USER_EXTENTS, building for each block a rowid to match row 1; the idea was to execute a SELECT to get the corresponding row, and, in case of error (NOT no data found, I can't remember the exact number) decide that the block was empty. I first wrote this on Oracle 6 to find the HWM (there was no ANALYZE then) by running a kind of dichotomic search. It was fast and reasonably precise (in fact, much more than the first versions of ANALYZE ... ESTIMATE). I guess that a variation on the same idea could be used in your case.

-- 
Regards,

Stephane Faroult
Oriole Ltd
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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