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11 July, 2013

Interesting Bugs in 12cR1

Oracle has documented known bugs in 12.1

Some that I find interesting (without having tested them, but only relying on the documentation) are :

Bug 16933305
Adding a nullable column with a default value and then later unsetting the default value in an Oracle Database 12c Release 1 (12.1) environment will not unset the default (back to NULL) despite the data dictionary reflecting the change to a default value of NULL. The statements that are impacted are ALTER TABLE x ADD (y NUMBER DEFAULT 99) followed by a subsequent ALTER TABLE x MODIFY (y DEFAULT NULL) where y is a nullable column.
Workaround: Unset the default by using the ALTER TABLE x MODIFY (y DEFAULT TRIM('')) statement which has the same semantic result as unsetting the default.


Bug 16873173
It is possible for an index fast full scan of a prefix compressed index to fail with ORA-600[6033] error.
Workaround: Retry the query or force an alternative access path with an appropriate hint.


Bug 16788520 and Bug 15968058
If shared server is enabled, queries on object link views in a PDB may crash. Object link views are all Oracle supplied and are mostly DBA_HIST views. A full list can be found using the following command:
SELECT OWNER, OBJECT_NAME FROM ALL_OBJECTS WHERE SHARING='OBJECT LINK' AND OBJECT_TYPE='VIEW'
Workaround: Disable shared server when querying these views.


Bug 16571451
SQL plan directives are not used when the OPTIMIZER_DYNAMIC_SAMPLING initialization parameter is set to the default value of2.
Workaround: Set the OPTIMIZER_DYNAMIC_SAMPLING initialization parameter to a value greater than 2.


Bug 16047938
Concurrent UNION ALL is automatically invoked for qualifying statements only when the UNION ALL statement is in a subselect statement. For example, the following command will execute all branches concurrently:
SELECT * FROM (SELECT FROM ... UNION ALL ... UNION ALL)
However, the exact same UNION ALL statement not executed as a subselect statement will not.
Workaround: Either embed the UNION ALL construct as a subselect statement or use the following statement to disable legacy code constraints:
ALTER SESSION SET "_fix_control"='6748058:0';


Bug 14851837
Tables containing TIMESTAMP WITH LOCAL TIME ZONE data cannot be moved between databases using transportable tablespace technology when the time zones of the source and target databases are different. Each affected table will be flagged during import with the following error:
ORA-39360, Table ""."" skipped due to transportable import and TSLTZ issues. 
Workaround: Convert the target database to the same time zone as the source database or move the affected tables with the conventional Data Pump Export and Import.
Bug 14621745
Certain errors raised while using the ALTER TABLE MOVE ONLINE statement can be ignored.
Workaround: None.
Bug 13877504
When threaded execution is enabled (threaded_execution=TRUE) in the initialization parameter file on UNIX platforms, native authentication (that is, connect / as sysdba or connect /) is not supported.
Workaround: Use password-based authentication. Native authentication will not work for connections where the server execution is a thread.
Bug 14575666
In 12.1, the default value for the SQLNET.ALLOWED_LOGON_VERSION parameter has been updated to 11. This means that database clients using pre-11g JDBC thin drivers cannot authenticate to 12.1 database servers unless theSQLNET.ALLOWED_LOGON_VERSION parameter is set to the old default of 8.
This will cause a 10.2.0.5 Oracle RAC database creation using DBCA to fail with the ORA-28040: No matching authentication protocol error in 12.1 Oracle ASM and Oracle Grid Infrastructure environments.
Workaround:  Set SQLNET.ALLOWED_LOGON_VERSION=8 in the $crs_home/network/admin/sqlnet.ora file.
Use the workaround before running 10.2.0.5 DBCA to create a database using 12.1 Oracle ASM and Oracle Grid Infrastructure.
Bug 16177073
Mixed case hostnames are not supported by the Oracle Universal Installer (OUI) for Oracle RAC or Cluster Ready Services (CRS) homes.
Workaround:  Do not use mixed case host names.
Bug 16903140
A new feature was added in Oracle Database 12c Release 1 (12.1) to support change tracking across resetlogs during the execution of an ALTER DATABASE OPEN RESETLOGS statement. This is achieved by deleting bitmaps that are not required because they cover changes that were made after the specified resetlogs point-in-time. There is an issue with the bitmap deleting that can cause error ORA-600 [krccchs_1] during OPEN RESETLOGS.
Workaround: Disable and reenable change tracking. You must disable change tracking before executing the ALTER DATABASE OPEN RESETLOGS statement, and then re-enable change tracking after the open resetlogs operation is complete.
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