Select Query Failing with ORA-07445

Issue:

Oracle DB: 12.1.0.2

While running one select query it was failing with below exception.

ORA-10173: Dynamic Sampling time-out error

ORA-07445: exception encountered: core dump [qcdlgcd()+70] [SIGSEGV] [ADDR:0x4] [PC:0xCDFB0E6] [Address not mapped to object] []

Troubleshoot:

Seeing the ORA-10173, I initially thought it might be the issue with dynamic sampling triggered by sql plan directive, I have gathered stats on the table which didn’t work.

Later disabled dynamic sampling at the session level to verify , query again failed with ORA-07445

Resolution:

Later came across oracle MOS note 2028777.1 mentioning to set the hidden parameter to false.

alter session set “_index_join_enabled”=false;

My symptoms for the issue are same after enabling the 10053 trace and checking the _index_join_enabled parameter.

References:

ORA-07445: core dump [qcdlgcd()+70] for Union All Statement : No More Data To Read From Socket (Doc ID 2028777.1)

ORA-10173: Dynamic Sampling time-out error in alert.log (Doc ID 1491818.1)

 

 

 

 

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ORA- 28040: No matching Authentication protocol after 12c Upgrade

Issue:

Web application was not working, when connecting through ODBC application team is getting error ORA-28040 .

What Was changed:

Oracle database upgraded from oracle 11.2.0.2 to 12.1.0.2

Resolution/Workaround:

SQLNET.ALLOWED_LOGON_VERSION default is changed to 11 from 8 in earlier versions.  We need to modify the parameter to value 9 or less. SQLNET.ALLOWED_LOGON_VERSION is depreciated in 12c, SQLNET.ALLOWED_LOGON_VERSION_SERVER and SQLNET.ALLOWED_LOGON_VERSION_CLIENT replaced this parameter.

Ref: https://docs.oracle.com/database/121/NETRF/sqlnet.htm#NETRF2016

ORA-39126 – During Schema Export

Issue:

Schema export form system user failed with below errors.

Estimate in progress using BLOCKS method…
ORA-39126: Worker unexpected fatal error in KUPW$WORKER.CONFIGURE_METADATA_UNLOAD [ESTIMATE_PHASE]
ORA-01422: exact fetch returns more than requested number of rows

ORA-06512: at “SYS.DBMS_SYS_ERROR”, line 95
ORA-06512: at “SYS.KUPW$WORKER”, line 9001

—– PL/SQL Call Stack —–
object line object
handle number name
4069d2ac0 20462 package body SYS.KUPW$WORKER
4069d2ac0 9028 package body SYS.KUPW$WORKER
4069d2ac0 6814 package body SYS.KUPW$WORKER
4069d2ac0 13688 package body SYS.KUPW$WORKER
4069d2ac0 2654 package body SYS.KUPW$WORKER
4069d2ac0 9697 package body SYS.KUPW$WORKER
4069d2ac0 1775 package body SYS.KUPW$WORKER
4053c83e8 2 anonymous block

Solution:

There was a DUAL table created under SYSTEM user having multiple rows.

SQL> select table_name,owner from dba_Tables where table_name=’DUAL’;

TABLE_NAME OWNER
—————————— ——————————
DUAL SYS
DUAL SYSTEM

SQL> select * from dual;

D

X
X
X
X

Dropped the custom dual table created under system and the export worked fine.

drop table system.dual;