Wednesday 11 April 2012

All about database checkpoints and Partial checkpoint in 11.2.0.2


All about Database checkpoints :
Reference: http://www.dbafree.net/wp-content/uploads/2011/05/CheckPoints.pdf

Partial checkpoint is done each time a parallel query is started.


DB_UNRECOVERABLE_SCN_TRACKING

Property                                                                            Description
Parameter                                                                         typeBoolean
Default value                                                                    true
Modifiable                                                                        ALTER SESSION, ALTER SYSTEM
Range of values                                                                   true | false
Basic                                                                                   No
Oracle RAC                                                                        Multiple instances must have the same value


DB_UNRECOVERABLE_SCN_TRACKING
enables or disables the tracking of unrecoverable (NOLOGGING) direct-path insert and load operations.

When the value is set to true, updates are made to the controlfile that maintains the V$DATAFILE.UNRECOVERABLE_CHANGE# and V$DATAFILE.UNRECOVERABLE_TIME columns.

When the value is set to false, updates are not made to the controlfile. Setting this parameter to false may improve performance of direct-path NOLOGGING operations.

Note:The DB_UNRECOVERABLE_SCN_TRACKING initialization parameter is available starting with Oracle Database 11g Release 2 (11.2.0.2).

This is a new feature in 11.2.0.2. Usefull when we have  logical corruption due to nologging operations.

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