ursor_sharing=SIMILAR 引发大量的 cursor: mutex S
---------- ---------------------------------------------------------------- ----------- ---------------- --------------- ----------
1 cursor: mutex S 8196 574159937294 113469206148 1
1 DB CPU 8196 264925348737 94172222209 2
1 library cache lock 8196 377415652600 58003457267 3
1 direct path read 8196 16531321401 4584378285 4
1 db file sequential read 8196 2798779765 1387124732 5
默认一小时的AWR event
可以看到基本处于崩溃的边缘，其原因MOS解释如下：
GOAL
Customer upgraded the DB Repository for Oracle Waveset from Oracle 10g to Oracle 11g.
Cursor sharing was set to SIMILAR as per the Oracle Waveset Documentation in 10g.
Child cursors were getting released in 10g. Customer noticed child cursors were not getting released in 11g.
As per the documentation in MOS 1169017.1 cursor sharing should be exact or force.
SOLUTION
The recommendation to set the 'cursor_sharing' option as 'SIMILAR' was to remedy the known issues when 'cursor_sharing' was set to be the default 'EXACT' option in previous versions of Oracle Waveset and Oracle 10g as repository.
Since the Oracle 11g database deprecates the 'SIMILAR' option, the recommendation now is to set 'cursor_sharing' to 'FORCE'.
REFERENCES
BUG:13983028 - RECOMMENDATION FOR CURSOR_SHARING PARAMETER WITH ORACLE 11G REPOSITORY记录一下
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