Oracle 12.2 RAC 報錯ora-600 ora-07445

報錯如下：
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
2017-11-22 13:56:36.095000 +08:00
Exception [type: SIGSEGV, Invalid permissions for mapped object] [ADDR:0x7F358CE5F7E3] [PC:0xAB3E99F, evaudc()+127] [flags: 0x0, count: 1]
Errors in file /oracle/app/db/diag/rdbms/tsscdb/TSSCDB2/trace/TSSCDB2_ora_59052.trc  (incident=122179) (PDBNAME=TSSDB):
ORA-07445: exception encountered: core dump [evaudc()+127] [SIGSEGV] [ADDR:0x7F358CE5F7E3] [PC:0xAB3E99F] [Invalid permissions for mapped object] []
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
2017-11-22 13:57:34.132000 +08:00
Exception [type: SIGSEGV, Invalid permissions for mapped object] [ADDR:0x7F7C412B539A] [PC:0xAB3E99F, evaudc()+127] [flags: 0x0, count: 1]
Errors in file /oracle/app/db/diag/rdbms/tsscdb/TSSCDB2/trace/TSSCDB2_ora_63258.trc  (incident=122617) (PDBNAME=TSSDB):
ORA-07445: exception encountered: core dump [evaudc()+127] [SIGSEGV] [ADDR:0x7F7C412B539A] [PC:0xAB3E99F] [Invalid permissions for mapped object] []
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
2017-11-22 13:57:48.377000 +08:00
Exception [type: SIGSEGV, Invalid permissions for mapped object] [ADDR:0x7F7B710B10E2] [PC:0xAB3E99F, evaudc()+127] [flags: 0x0, count: 1]
DDE: Problem Key 'ORA 7445 [evaudc]' was completely flood controlled (0x6)
Further messages for this problem key will be suppressed for up to 10 minutes
2017-11-22 13:58:40.155000 +08:00
Exception [type: SIGSEGV, Invalid permissions for mapped object] [ADDR:0x7F096426B19D] [PC:0xAB3E99F, evaudc()+127] [flags: 0x0, count: 1]
Errors in file /oracle/app/db/diag/rdbms/tsscdb/TSSCDB2/trace/TSSCDB2_ora_63564.trc  (incident=121985) (PDBNAME=TSSDB):
ORA-07445: exception encountered: core dump [evaudc()+127] [SIGSEGV] [ADDR:0x7F096426B19D] [PC:0xAB3E99F] [Invalid permissions for mapped object] []
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
2017-11-22 13:59:33.141000 +08:00
Exception [type: SIGSEGV, Invalid permissions for mapped object] [ADDR:0x7FB8400F327B] [PC:0xAB3E99F, evaudc()+127] [flags: 0x0, count: 1]
Errors in file /oracle/app/db/diag/rdbms/tsscdb/TSSCDB2/trace/TSSCDB2_ora_63999.trc  (incident=121796) (PDBNAME=TSSDB):
ORA-07445: exception encountered: core dump [evaudc()+127] [SIGSEGV] [ADDR:0x7FB8400F327B] [PC:0xAB3E99F] [Invalid permissions for mapped object] []
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.

透過對上述trace資訊的檢查發現除了SQL auto adviser外，還有一條SQL語句出發了該問題，該sql 語句在plsql或者伺服器端執行都會出現如下報錯：
    ORA-03113: 通訊通道的檔案結尾
    程式 ID: 5896
    會話 ID: 191 序列號: 1
同時出發ora-07445報錯。
透過netalink檢視發現應該是12C的一個bug，透過修改如下引數可解決：

ora-07445: exception encountered: core dump [evaudc()+180] Rediscovery Notes When query has all of below:
1) special ordering operator in outer query(example: ORDER BY ...DESC/ASC
NULLS LAST)
2) query having view on which view merge takes place
3) there is FI usage i.e. order by column is fetched from Functional index Workaround alter session set "_replace_virtual_columns"=false;
or
alter session set "_simple_view_merging"=false;
alter session set "complex_view_merging"=false;

具體見：
    Bug 21869685 - ORA-7445: exception encountered: core dump [evaudc()+180] (Doc ID 21869685.8)