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If you use sequence numbers, then always use CACHE with the NOORDER option for optimal sequence number generation performance. With the CACHE option, however, you may have gaps in the sequence numbers. If your environment cannot tolerate sequence number gaps, then use the NOCACHE option or consider pre-generating the sequence numbers. If your application requires sequence number ordering but can tolerate gaps, then use CACHE and ORDER to cache and order sequence numbers in Oracle RAC. If your application requires ordered sequence numbers without gaps, then use NOCACHE and ORDER. This combination has the most negative effect on performance compared to other caching and ordering combinations.
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If you use indexes, then consider alternatives, such as reverse key indexes to optimize index performance. Reverse key indexes are especially helpful if you have frequent inserts to one side of an index, such as indexes that are based on insert date. |
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