Re: Calculating LIOs

  • From: Tanel Põder <tanel.poder.003@xxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 13 Aug 2004 19:02:43 +0300


> UNIQUE SCAN followed by a TABLE ACCESS BY ROWID.  Well, how big is the =
> index?  How many levels?  Remember that regardless of the value =
> specified in the pk_column predicate, the number of levels from the =
> index root block to any leaf block is always the same.  So, if the index =
> has a BELVEL of, say, 3, then to get from the root to the leaf =
> containing 123 will be 4 buffer gets.  The TABLE ACCESS BY ROWID is one =
> more buffer get.  So, that's a total of 5 buffer gets. =20

Also, the LIO count may increase when Oracle has to construct a read
consistent clone of index/datablocks...


Please see the official ORACLE-L FAQ:
To unsubscribe send email to:  oracle-l-request@xxxxxxxxxxxxx
put 'unsubscribe' in the subject line.
Archives are at
FAQ is at

Other related posts: