Saturday, June 18, 2011

Tune full table scans with LOB objects

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Problem Description: Full table scans with a lob objects

Symptoms:

1.  Many Full table scans on a hot table (almost 1 million of records with lobs columns).

2. Table becomes highly fragmented due to many deletes and updates.

3. Using Move command to eliminate fragmentation will not work with LOB segments as lobs usually spread on more than one block

Solution:

Moving lob segments on higher block size like 32K would decrease the number of visits to storage to retrieve blocks.

    
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