Re: Blocks in DBA_TABLES and DBA

From: Howard J. Rogers <dba_at_hjrdba.com>
Date: Fri, 3 May 2002 09:09:03 +1000
Message-ID: <aasgvp$ime$1@lust.ihug.co.nz>

Dba_segments will show the total number of blocks allocated to a segment, used or unused. Blocks in dba_tables shows the blocks below the High Water Mark (or, rather more accurately in 9i, blocks which would be read by a full table scan). Empty_blocks shows you the number of blocks which are above the high water mark (or, again, in 9i, blocks which won't be read by a full table scan).

Bold prediction: add blocks and empty_blocks together in dba_tables, and the total will match what you get listed as blocks in dba_segments.

Regards
HJR "Jeff Y. Y." <yuanjeff_at_yahoo.com> wrote in message news:a2bc9497.0205021348.38929b76_at_posting.google.com...
> What is the difference between the BLOCKS column in dba_tables and
> dba_segments?
> The two numbers in my database are very different. Or say
> dba_segments.blocks - dba_table.blocks = ?
>
> What is the mean of empty_blocks in dba_tables? Does it include the
> blocks above HWM? Is it the block available for data insert?
>
> Thanks a lot.
Received on Thu May 02 2002 - 18:09:03 CDT

Re: Blocks in DBA_TABLES and DBA_SEGMENTS