Oracle Tidbits – August 2014

Oracle *daily* TidBits” published at on all weekdays in August 2014. You will also see these tidbits, one tidbit at a time, for each page refresh on the right side of this blog as well… Hope you find these helpful to learn something new or to remind you of its existence and use…

Date TidBit
1-Aug X$NULL is an internal account that represents the absence of database user in a session and the actual session user is an application user supported by Oracle Real Application Security. XS$NULL has no privileges and does not own any database object. No one can authenticate as XS$NULL, nor can authentication credentials ever be assigned to XS$NULL.
4-Aug The Unified Auditing in Oracle Database 12c is enabled by relinking the Oracle executable using command “make -f uniaud_on ioracle ORACLE_HOME=$ORACLE_HOME”. On Windows platforms, just rename the “%ORACLE_HOME%/bin/orauniaud12.dll.option” file to “%ORACLE_HOME%/bin/orauniaud12.dll”.
5-Aug If you are not licensed for Diagnostic and Tuning Pack of Oracle Database, you can set the parameter CONTROL_MANAGEMENT_PACK_ACCESS to NONE. The default value is DIAGNOSTIC+TUNING, meaning both packs are licensed. Set to DIAGNOSTIC to enable diagnostic pack that includes automatic database diagnostic monitoring (ADDM) and AWR. The TUNING pack includes SQL Tuning Advisor, SQL Access Advisor, and so on.
6-Aug When creating CDB in Oracle Database 12c, make sure you pick appropriate character set. Only databases with a compatible character set can be plugged into the CDB.
7-Aug New in The STANDBYS clause of the CREATE PLUGGABLE DATABASE statement specifies whether the new PDB is included in standby CDBs. You can specify ALL to include the new PDB in all of the standby CDBs. Specify NONE to exclude the new PDB from all of the standby CDBs.
8-Aug In Multitenant database configuration, a CDB uses a single SPFILE or a single text initialization parameter file (PFILE). Values of initialization parameters set for the root container can be inherited by PDBs. The root (CDB$ROOT) must be the current container when you operate on an SPFILE.
11-Aug New in The NO DATA clause of the CREATE PLUGGABLE DATABASE statement specifies that a PDB’s data model definition is cloned but not the PDB’s data. The dictionary data in the source PDB is cloned, but all user-created table and index data from the source PDB is discarded. This clause is useful for quickly creating clones of a PDB with only the object definitions and no data. This clause does not apply to the SYSTEM and SYSAUX tablespaces.
12-Aug In Multitenant database configuration, the PDB can inherit the default timezone from the root container or can set its own timezone.
13-Aug In Multitenant database configuration, there is a default temporary tablespace for the entire CDB. You optionally can create additional temporary tablespaces for use by individual PDBs.
14-Aug In a CDB, the UNDO_MANAGEMENT initialization parameter must be set to AUTO, and an undo tablespace is required to manage the undo data. Only a common user who has the appropriate privileges and whose current container is the root (CDB$ROOT) can create an undo tablespace.
15-Aug To create a CDB, the CREATE DATABASE statement must include the ENABLE PLUGGABLE DATABASE clause. When the ENABLE PLUGGABLE DATABASE clause is not included in the CREATE DATABASE statement, the newly created database is a non-CDB.
18-Aug The USER_TABLESPACES clause available in of the CREATE PLUGGABLE DATABASE statement specifies which tablespaces are available in the new PDB. Use this clause to separate the data for multiple schemas into different PDBs. For example, when you move a non-CDB to a PDB, and the non-CDB had a number of schemas that each supported a different application, you can use this clause to separate the data belonging to each schema into a separate PDB, assuming that each schema used a separate tablespace in the non-CDB.
19-Aug The PATH_PREFIX clause of the CREATE PLUGGABLE DATABASE statement ensures that all relative directory object paths associated with the PDB are restricted to the specified directory or its subdirectories. Use this clause when you want to ensure that a PDB’s files reside in a specific directory and its subdirectories when relative paths are used for directory objects.
20-Aug When you drop a CDB using DROP DATABASE statement, the root, seed, and all of its all of its PDBs (including their data) are also dropped. Individual PDBs are dropped using the DROP PLUGGABLE DATABASE statement.
21-Aug In a CDB environment, ADDM does not analyze one PDB at a time. ADDM runs with a target of either the entire instance or Oracle RAC database.
22-Aug Most CDB_ dictionary views in a CDB include the CON_ID column. Value of 0 identifies the data pertains to entire CDB, 1 pertains to root, 2 pertains to seed and 3-254 pertains to each PDB.

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