| HASH partitioning [message #174548] |
Mon, 29 May 2006 08:48  |
Nau
Messages: 24
Registered: October 2004
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Junior Member |
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I have a question about HASH partitioning. I have never used this type of partition (only partition by range).
I want to know the advantages of HASH partitioning compared with range partitioning.
In which cases is useful HASH partitioning??, what kind of tables??
Any advice about HASH partitioning will be greatly apreciatted.
Thanks in advance
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| Re: HASH partitioning [message #174658 is a reply to message #174548] |
Tue, 30 May 2006 03:28  |
rleishman
Messages: 3728
Registered: October 2005
Location: Melbourne, Australia
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Senior Member |
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Hash partitions a generally less functional than RANGE partitions for improving SQL performance. Predicates such as LIKE, <, >, and BETWEEN cannot perform a Partition-Prune with HASH partitions.
You may still get some performance benefits with equals predicates that cannot use an index, and also with partition-wise joins on tables that have the same partitioning strategy.
Only use HASH partitions if the data is not time-sensitive, and your chosen partition-key does not have convenient evenly-distributed ranges. There is a blurb to this effect somewhere in the Oracle doco - probably the Performance Tuning Guide or the Data Warehousing Guide.
Ross Leishman
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