11.2.0.1bug引发的报错：ORA-07445: exception encountered

问题背景：客户反馈DB每天产生的incident日志很多，需要排查原因

1> 查看alert日志发现大量的ORA-07445、ORA-00600错误

 1 Errors in file /data/oracle/diag/rdbms/bydata/bydata/trace/bydata_mmon_3667.trc  (incident=111052):
 2 
 3 ORA-00600: internal error code, arguments: [6200], [18446744073709551615], [], [], [], [], [], [], [], [], [], []
 4 
 5 Exception [type: SIGSEGV, SI_KERNEL(general_protection)] [ADDR:0x0] [PC:0x2278EA1, kghstack_err()+85] [flags: 0x0, count: 1]
 6 
 7 Errors in file /data/oracle/diag/rdbms/bydata/bydata/trace/bydata_mmon_3667.trc  (incident=111053):
 8 
 9 ORA-07445: exception encountered: core dump [kghstack_err()+85] [SIGSEGV] [ADDR:0x0] [PC:0x2278EA1] [SI_KERNEL(general_protection)] []
10 
11 ORA-00600: internal error code, arguments: [6200], [18446744073709551615], [], [], [], [], [], [], [], [], [], []
12 
13 Incident details in: /data/oracle/diag/rdbms/bydata/bydata/incident/incdir_111053/bydata_mmon_3667_i111053.trc
14 
15 Mon Oct 21 09:50:30 2019

一般情况下，ORA-600被证明为oracle的内部错误，通常由数据文件的坏块或者oracle的bug引起

首先查看是否有数据文件坏块,

 1 Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
 2 
 3 With the Partitioning, OLAP, Data Mining and Real Application Testing options
 4 
 5 [oracle@OA_oracle incident]$ dbv file=/data/oracle/oradata/oradb/tablespace/oradb_DATA.DBF
 6 
 7 DBVERIFY: Release 11.2.0.1.0 - Production on Mon Oct 21 10:25:28 2019
 8 
 9 Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
10 
11 DBVERIFY - Verification starting : FILE = /data/oracle/oradata/oradb/tablespace/oradb_DATA.DBF
12 
13 DBVERIFY - Verification complete
14 
15 Total Pages Examined         : 57600
16 
17 Total Pages Processed (Data) : 20706
18 
19 Total Pages Failing   (Data) : 0
20 
21 Total Pages Processed (Index): 11725
22 
23 Total Pages Failing   (Index): 0
24 
25 Total Pages Processed (Other): 13062
26 
27 Total Pages Processed (Seg)  : 0
28 
29 Total Pages Failing   (Seg)  : 0
30 
31 Total Pages Empty            : 12107
32 
33 Total Pages Marked Corrupt   : 0
34 
35 Total Pages Influx           : 0
36 
37 Total Pages Encrypted        : 0
38 
39 Highest block SCN            : 296071350 (0.296071350)

查看所有的数据文件均未发现坏块现象

2> 查看trace里有大量的SQL引用多个left outer join

查看mos和BUG 9050716比较匹配，当前SQL引用多个left outer join，在11.2.0.1.0版本，外关联存在多个BUG，

建议禁用_optimizer_join_elimination_enabled参数问题解决

查看隐含参数的语句

 1 SELECT   ksppinm, ksppstvl, ksppdesc  FROM   x$ksppi x, x$ksppcv y   WHERE   x.indx = y.indx AND  ksppinm like '_optimizer%';
 2 
 3 SQL> SELECT   ksppinm, ksppstvl, ksppdesc  FROM   x$ksppi x, x$ksppcv y   WHERE   x.indx = y.indx AND  ksppinm like '_optimizer_join%';
 4 
 5  
 6 
 7 KSPPINM                             KSPPSTVL                  KSPPDESC
 8 
 9 ----------------------------------- ------------------------- ---------------------------------------------------------------------------
10 
11 _optimizer_join_sel_sanity_check    TRUE                      enable/disable sanity check for multi-column join selectivity
12 
13 _optimizer_join_order_control       3                         controls the optimizer join order search algorithm
14 
15 _optimizer_join_elimination_enabled TRUE                      optimizer join elimination enabled
16 
17 _optimizer_join_factorization       TRUE                      use join factorization transformation
18 
19  
20 
21 修改隐含参数_optimizer_join_elimination_enabled
22 
23 alter system set "_optimizer_join_elimination_enabled" =false scope=both;