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Temporary tablespace里面只有temporary segment,没有 permanent segement.对temporary tablespace的操作,不会更新data dictionary,执行速度会非常快.因为Permanent 类型的segment进行更新的话,都需要更新数据字典.不同的用户可以使用不同的临时表空间.不同的表空间可以分步在不同的磁盘上;假如不同的用户具有不同的临时表空间,在进行大数据排序的时候,就可以减少同一个磁盘的I/O读写,提高性能.一个segment可以被不同的用户使用,使用里面不同的extent.为不同的用户设置不同的临时表空间.Temp 阅读全文
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OEMPGA Target Advice HistogramsV$PGA_TARGET_ADVICE_HISTOGRAM predicts how histograms shown in V$SQL_WORKAREA_HISTOGRAM evolve.STATISTICS_LEVEL must be set to at least TYPICAL.Auto PGA and OEMOverviewThe automatic sort area management feature is :Easier to set up and size than the *_AREA_SIZEP parame 阅读全文
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PGA Target Advice StatisticsV$PGA_TARGET_ADVICE predicts how cache hit percentages shown in V$PGASTAT evolve.STATISTICS_LEVEL must be set to at least TYPICAL.(提示:如果想使V$PGA_TARGET_ADVICE工作,必须将STATISTIC_LEVEL修改成至少TYPICAL级别)SQL> select * from v$PGA_TARGET_ADVICE;PGA_TARGET_FOR_ESTIMATE PGA_TARGET_FA 阅读全文
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cache hit percentage这个参数,可以作为DBA衡量PGA相关参数指标是否合理的一个重要标准.SQL> SELECT low_optimal_size "Low",High_optimal_size "Hight",optimal_executions "Opt",onepass_executions "One",multipasses_executions "Multi",total_executions "Total" 2 FROM v$sql_wo 阅读全文
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Auto Sort Area ManagementkParameter for automatic sort area management:-PGA_AGGREGATE_TARGET(Ranges from 10MB to 4000GB)-WORKAREA_SIZE_POLICY (AUTO | MANUAL)(Oracle 推荐使用自动化管理)Replaces all *_AREA_SIZE parametersSQL> show parameter PGA_AGGREGATENAME TYPE VALUE---... 阅读全文
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ObjectivesAfter completing this lesson,you should be to do the following:List the operations that use temporary space.Create and monitor temporary tablespaces.Identify actions that use the temporary tablespaceDescribe and different disk sorts and memory sortsIdentify the SQL operations that require 阅读全文