Oracle 11.2.0.2上SQL TUNING的bug。

数据库版本为11.2.0.2 RAC for Solaris，错误信息为：

Thu Jul 05 22:00:01 2012
Begin automatic SQL Tuning Advisor run for special tuning task "SYS_AUTO_SQL_TUNING_TASK"
Thu Jul 05 22:28:35 2012
Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x4] [PC:0x102B3CC08, qsmmixComputeClusteringFactor()+1640] [flags: 0x0, count: 1]
Errors in file /opt/oracle/app/oracle/diag/rdbms/orcl/orcl1/trace/orcl1_j002_7688.trc (incident=192450):
ORA-07445: exception encountered: core dump [qsmmixComputeClusteringFactor()+1640] [SIGSEGV] [ADDR:0x4] [PC:0x102B3CC08] [Address not mapped to object] []
Incident details in: /opt/oracle/app/oracle/diag/rdbms/orcl/orcl1/incident/incdir_192450/orcl1_j002_7688_i192450.trc
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
Thu Jul 05 22:28:38 2012
Dumping diagnostic data in directory=[cdmp_20120705222838], requested by (instance=1, osid=7688 (J002)), summary=[incident=192450].
Thu Jul 05 22:28:41 2012
Sweep [inc][192450]: completed
Sweep [inc2][192450]: completed

不需要其他信息，上面的报错就足以判断，问题发生在SQL TUNING自动运行的JOB中。显然这是Oracle的bug。

果然MOS文档Bug 9746210 - ORA-7445 [qsmmixComputeClusteringFactor] from SQL tuning [ID 9746210.8]描述了这个问题，且确认影响版本就是11.2.0.2。Oracle在11.2.0.3和11.2.0.2.4中修正了这个问题。

这个问题对于数据库的运行本身也没有什么影响，可以直接忽略掉，甚至可以将SQL TUNING对应的SCHEDULER直接停止。