Oracle Version： 11.2.0.2
Operation System：HP-UXItanium 11.31
2.Alert log中信息Tue Oct 16 22:27:31 2012
Exception [type: SIGSEGV,Address not mapped to object] [ADDR:0xC00000000] [PC:0x400000000631B880,evaopn3()+384] [flags: 0x0, count: 1]
Errors in file/oracle/app/oracle/diag/rdbms/wzpartdb/wzpartdb/trace/wzpartdb_j004_19591.trc (incident=56673):
ORA-07445: exceptionencountered: core dump [evaopn3()+384] [SIGSEGV] [ADDR:0xC00000000][PC:0x400000000631B880] [Address not mapped to object] []
Incident details in:/oracle/app/oracle/diag/rdbms/wzpartdb/wzpartdb/incident/incdir_56673/wzpartdb_j004_19591_i56673.trc
Use ADRCI or Support Workbench to packagethe incident.
See Note 411.1 at My Oracle Support forerror and packaging details.
Tue Oct 16 22:27:56 2012
Dumping diagnostic data indirectory=[cdmp_20121016222756], requested by (instance=1, osid=19591 (J004)),summary=[incident=56673].
Tue Oct 16 22:27:58 2012
Sweep [inc][56673]: completed
Sweep [inc2][56673]: completed
3.问题定位
与ORA-7445 相关的错误多与bug相关，一般我们需要关注第一个参数的类型，这里是evaopn3。 MOS上专门的文章介绍这个，参考：
ORA-7445[evaopn3] (Doc ID 860969.1)
这里与我们的错误：
ORA-07445: exceptionencountered: core dump [evaopn3()+384] [SIGSEGV] [ADDR:0xC00000000][PC:0x400000000631B880] [Address not mapped to object] []
Bug 13369579 - dump on evaopn3 withfunction base index and ORDER BY (Doc ID 13369579.8)
Bug 12724375 - ORA-7445 [evaopn3] fromXQuery with GROUP BY (Doc ID 12724375.8)
Bug 12672969 - Assorted Dumps withaggregate expression in ORDER BY (Doc ID 12672969.8)
Bug 13817586 - Dump on evaopn3 withEncrypted Columns (Doc ID 13817586.8)
通过排除，我这里是bug：12672969。
Bug 12672969 - Assorted Dumps withaggregate expression in ORDER BY (Doc ID 12672969.8)
查看trace，确定了某SQL在order by中使用了aggregation function。执行该SQL时就会触发ORA-7445的错误。
可以通过如下方式验证：
create table test1 ( col1 number, col2number );
insert into test1 values( 1, 1 );
commit;
select count(*)
from(select col2
from test1
group by col2 order by (sum(col2)+1));
Rediscovery Notes:
1.ORA-7445 in aggregation evaluation function including evaopn3
2.Order by elimination is performed
3. Set function exists in the middle of theoperator tree in order by
clause
4.The fix for bug 8772028 is present
4.解决方案MOS 上解决方案是修改参数：
alter sessionset "_optimizer_order_by_elimination_enabled"=false;
但是这个是个隐含参数，修改可能会引起其他的问题，Oracle 争对这个bug 提供了Patch：12672969.
可以在应用Patch 之后，在执行触发bug的SQL，确认bug 修复情况。