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Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 471
Chapter 10: Managing Database Use
The extent sizes of a table should be _____ to improve performance of the table scans.
A. All equal
B. No larger than five times DB_BLOCK_SIZE
C. Equal to the size of the biggest possible row
D. A multiple DB_FILE_MULTIBLOCK_READ_COUNT
Answer D is correct. The extent sizes of a table should be multiple
DB_FILE_MULTIBLOCK_READ_COUNT parameter in initSID.ora file to improve
performance of the table scans.
A: The equal extent sizes will not improve performance of the table scans, because for full scans
you need to try keep data in less extents as possible.
B: Each extent contains at least 5 data blocks, so if you will use no larger than 5 times
DB_BLOCK_SIZE it will be minimal possible size of extent. To store data you will need a lot of
extents in this case, it will decrease table scans performance.
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This document was uploaded on 03/08/2014.
- Fall '09