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Identification of sparse tables in the database to perform reorg on those tables for performance imp

edited Dec 1, 2011 7:09PM in Database Tuning (MOSC) 7 comments

Hello there,

We are considering to reorg sparse tables as per recommendation from Oracle..as I have been reading from http://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:223962400346759456.

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Recommendations

¿  Reorganize those indexes where Extra_Blocks is high (potential space to reclaim) and the leaf block density is low (i.e., less that 50-60%).
10.12  Sparse Tables

Many delete or update operations on a table over time can produce a sparse table. That means that the high water mark (HWM) of that table is representing a multiple of the really existing data in the table. During full table scans Oracle reads all blocks up to the High Water Mark (HWM). Those tables should be reorganized to improve performance and to need less disk space.

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