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Author Archives Richard Foote

Clustering Factor Calculation Improvement Part II (Blocks On Blocks)

My previous post on the new TABLE_CACHED_BLOCKS statistics gathering preference certainly generated some interest My blog hits for the week have gone off the charts !! One of the concerns raised by this new capability was that setting such a preference might result in really unrealistic and inaccurate Clustering Factor (CF) values, especially for those […]

Posted 14 May 2013 § Uncategorized ‡ Comments Off °

Important !! Clustering Factor Calculation Improvement (Fix You)

Believe me, this article is worth reading I’m currently not allowed to discuss Oracle 12c Database goodies but I am allowed to discuss things perhaps initially intended for 12c that are currently available and already back-ported to 11g. This includes a wonderful improvement in the manageability of how the Clustering Factor (CF) of an index can now […]

Posted 08 May 2013 § Uncategorized ‡ Comments Off °

Storage Indexes vs Database Indexes IV: 8 Column Limit (Eight Line Poem)

As Exadata Storage Indexes (SI) are purely memory only structures located on the Exadata storage servers, care needs to be taken in how much memory they can potentially consume. As a result, there is a limit of 8 columns (or 8 SIs) that can be defined for a given 1M storage region at any point […]

Posted 01 May 2013 § Uncategorized ‡ Comments Off °

1,000,000 Blog Visits (How I Made My Millions)

Things have certainly been busy lately so I haven’t had much of a chance to get back here for a while. Busy at work, busy at home, busy at play and even busy with a new David Bowie album to enjoy !! And yes, “The Next Day” is an absolutely stunning album by the great […]

Posted 30 April 2013 § Uncategorized ‡ Comments Off °

Index Block Dump: Index Only Section Part II (Station To Station)

Finally, we look at the last portion of the index block dump which refers to the actual 3 index entries in our demo that currently reside within the index leaf block we dumped previously. row#0[8021] flag: ——, lock: 0, len=15 col 0; len 5…

Posted 07 October 2010 § Uncategorized ‡ Comments Off °

So What Is A Good Cardinality Estimate For A Bitmap Index Column ? (Song 2)

As I’ve discussed previously, using a Bitmap index on a unique column makes little sense as the underling index must be larger than a corresponding B-tree index due to the implicit additional overheads associated with Bitmap indexes. As such, Ora…

Posted 13 April 2010 § Uncategorized ‡ Comments Off °