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PERF--ANALYZE Statement

原创 Linux操作系统 作者:vongates 时间:2019-05-05 13:18:05 0 删除 编辑

在Oracle中,我們可以用analyze語句來對table,index,cluster進行分析,通過分析可以得到關于指定對象的狀態和統計信息,并且能夠對指定對象的存儲格式進行驗証:通常我們能夠實現以下三個目的:

1.驗証table,index,cluster 的存儲結構。
2.收集table,index,cluster 的統計信息。
3.查找table,cluster中存在的行鏈接和行遷移的記錄。


Syntax:
   ANALYZE TABLE tablename COMPUTE|ESTIMATE|DELETE STATISTICS ptnOption options
   ANALYZE INDEX indexname COMPUTE|ESTIMATE|DELETE STATISTICS ptnOption options
ANALYZE CLUSTER clustername COMPUTE|ESTIMATE|DELETE STATISTICS options ptnOption PARTITION (partion) SUBPARTITION (subpartition) options VALIDATE STRUCTURE [CASCADE] [INTO tablename] LIST CHAINED ROWS [INTO tablename] COMPUTE|ESTIMATE STATISTICS FOR TABLE COMPUTE|ESTIMATE STATISTICS FOR ALL COLUMNS COMPUTE|ESTIMATE STATISTICS FOR ALL INDEXED COLUMNS COMPUTE|ESTIMATE STATISTICS FOR COLUMNS [SIZE int] column [SIZE int] When Estimating statistics you can optionally specify ... ESTIMATE STATISTICS SAMPLE n ROWS ... ESTIMATE STATISTICS SAMPLE n PERCENT

Validate structure will perform an integrity check - and will therefore lock the table/index/cluster while it is running.
If the INTO clause is used to store a list of chained rows in a table - the default tablename is CHAINED_ROWS

UTLCHAIN.sql - creates the chained_rows table

"50% of the population has a below average understanding of statistics."- Anon

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