NOTE OF ANALYZE

最新推荐文章于 2023-06-20 08:11:06 发布

转载最新推荐文章于 2023-06-20 08:11:06 发布 · 73 阅读

本文建议不要使用ANALYZE语句中的COMPUTE和ESTIMATE子句来收集Oracle优化器统计信息，因为这些子句仅为了向后兼容而保留。推荐使用DBMS_STATS包来并行收集统计信息、收集分区对象的全局统计信息，并以其他方式调整统计信息收集。对于与成本基础优化器无关的统计信息收集，仍需使用ANALYZE语句。

Do not use the COMPUTE and ESTIMATE clauses of
ANALYZE to collect optimizer statistics. These clauses are supported
for backward compatibility. Instead, use the DBMS_STATS package,
which lets you collect statistics in parallel, collect global statistics
for partitioned objects, and fine tune your statistics collection in
other ways. The optimizer, which depends upon statistics, will
eventually use only statistics that have been collected by DBMS_STATS.

You must use the ANALYZE statement (rather than DBMS_STATS)
for statistics collection not related to the cost-based optimizer, such
as:
■ To use the VALIDATE or LIST CHAINED ROWS clauses
■ To collect information on freelist blocks

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