Init.ora Parameter "_SQLEXEC_PROGRESSION_COST" [Hidden] Reference Note (文档 ID 68955.1)-优快云博客

本文详细介绍了Oracle数据库中参数_ SQLEXEC_PROGRESSION_COST的作用、描述、默认值及设置建议，帮助用户避免SQL共享问题，通过调整该参数来优化SQL执行性能。

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Parameter: _SQLEXEC_PROGRESSION_COST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Please note this is a hidden Oracle parameter and begins with an underscore
  character. The information on this parameter is made available to customers
  here as it can be used to avoid some cursor sharing bugs in Oracle8i.
  If you set this parameter then include a comment to explain why it is
  being set.

Versions:        This parameter can be set in Oracle 8.1.5 to 8.1.7 inclusive


Description
~~~~~~~~~~~
  SQL execution progression monitoring cost threshold.

  This parameter controls the optimizer cost used as the threshold
  for cutting off progression monitoring.  Progression monitoring
  involves extra function calls and row sources, so we don't
  want to cause this overhead on short operations; however, since
  the cost can be inaccurate there is a sliding threshold.
  The value defaults to 1000, but if set to zero, progression monitoring
  will be turned off.  If nonzero, then any statement with a costs less
  than the value will not be monitored.

  The progression monitoring output can be seen in <View:V$SESSION_LONGOPS>.

Support Notes
~~~~~~~~~~~~~
  Leaving this parameter at its default value can cause SQL statements
  not to be shared as detailed in Bug:1210242. Setting this
  parameter to 0 in the init.ora file can help avoid such problems.


Articles:
  Overview of Init.Ora Parameter Reference notes    Note:68462.1

   
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