96 DBMS_REDEFINITION

Using DBMS_REDEFINITION

• Overview

• Constants

• Operational Notes

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Overview

To achieve online redefinition, incrementally maintainable local materialized views are used. These logs keep track of the changes to the master tables and are used by the materialized views during refresh synchronization.

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Constants

The DBMS_REDEFINITION package uses the constants shown in Table 96-1, "DBMS_REDEFINITION Constants":

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Operational Notes

• CONS_USE_PK and CONS_USE_ROWID are constants used as input to the "options_flag" parameter in both the START_REDEF_TABLE Procedure and CAN_REDEF_TABLE Procedure. CONS_USE_ROWID is used to indicate that the redefinition should be done using rowids while CONS_USE_PK implies that the redefinition should be done using primary keys or pseudo-primary keys (which are unique keys with all component columns having NOT NULL constraints).

• CONS_INDEX, CONS_MVLOG,CONS_TRIGGER and CONS_CONSTRAINT are used to specify the type of the dependent object being (un)registered in REGISTER_DEPENDENT_OBJECT Procedure and UNREGISTER_DEPENDENT_OBJECT Procedure (parameter "dep_type").

  CONS_INDEX ==> dependent object is of type INDEX

  CONS_TRIGGER ==> dependent object is of type TRIGGER

  CONS_CONSTRAINT==> dependent object type is of type CONSTRAINT

  CONS_MVLOG ==> dependent object is of type MATERIALIZED VIEW LOG

• CONS_ORIG_PARAMS as used as input to the "copy_indexes" parameter in COPY_TABLE_DEPENDENTS Procedure. Using this parameter implies that the indexes on the original table be copied onto the interim table using the same storage parameters as that of the original index.

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Rules and Limits

For information about various rules and limits that apply to implementation of this package, see the Oracle Database Administrator's Guide.

Summary of DBMS_REDEFINITION Subprograms

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ABORT_REDEF_TABLE Procedure

This procedure cleans up errors that occur during the redefinition process. This procedure can also be used to terminate the redefinition process any time after the START_REDEF_TABLE Procedure has been called and before the FINISH_REDEF_TABLE Procedure is called. This process will remove the temporary objects that are created by the redefinition process such as materialized view logs.

Syntax

DBMS_REDEFINITION.ABORT_REDEF_TABLE (
   uname       IN VARCHAR2,
   orig_table  IN VARCHAR2,
   int_table   IN VARCHAR2,
  part_name    IN  VARCHAR2 := NULL);

Parameters

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CAN_REDEF_TABLE Procedure

This procedure determines if a given table can be redefined online. This is the first step of the online redefinition process. If the table is not a candidate for online redefinition, an error message is raised.

Syntax

DBMS_REDEFINITION.CAN_REDEF_TABLE (
   uname         IN  VARCHAR2,
   tname        IN  VARCHAR2,
   options_flag  IN  PLS_INTEGER := 1,
   part_name     IN  VARCHAR2 := NULL);

Parameters

Exceptions

If the table is not a candidate for online redefinition, an error message is raised.

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COPY_TABLE_DEPENDENTS Procedure

This procedure clones the dependent objects of the table being redefined onto the interim table and registers the dependent objects. This procedure does not clone the already registered dependent objects.

This subprogram is used to clone the dependent objects like grants, triggers, constraints and privileges from the table being redefined to the interim table (which represents the post-redefinition table).

Syntax

DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS(
   uname                    IN  VARCHAR2,
   orig_table               IN  VARCHAR2,
   int_table                IN  VARCHAR2,
   copy_indexes             IN  PLS_INTEGER := 1,
   copy_triggers            IN  BOOLEAN     := TRUE,
   copy_constraints         IN  BOOLEAN     := TRUE,
   copy_privileges          IN  BOOLEAN     := TRUE,
   ignore_errors            IN  BOOLEAN     := FALSE,
   num_errors               OUT PLS_INTEGER,
   copy_statistics          IN  BOOLEAN     := FALSE, 
   copy_mvlog               IN  BOOLEAN     := FALSE); 

Parameters

Usage Notes

• The user must check the column num_errors before proceeding to ensure that no errors occurred during the cloning of the objects.

• In case of an error, the user should fix the cause of the error and call the COPY_TABLE_DEPENDENTS Procedure again to clone the dependent object. Alternatively the user can manually clone the dependent object and then register the manually cloned dependent object using the REGISTER_DEPENDENT_OBJECT Procedure.

• All cloned referential constraints involving the interim tables will be created disabled (they will be automatically enabled after the redefinition) and all triggers on interim tables will not fire till the redefinition is completed. After the redefinition is complete, the cloned objects will be renamed to the corresponding pre-redefinition names of the objects (from which they were cloned from).

• It is the user's responsibility that the cloned dependent objects are unaffected by the redefinition. All the triggers will be cloned and it is the user's responsibility that the cloned triggers are unaffected by the redefinition.

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FINISH_REDEF_TABLE Procedure

This procedure completes the redefinition process. Before this step, you can create new indexes, triggers, grants, and constraints on the interim table. The referential constraints involving the interim table must be disabled. After completing this step, the original table is redefined with the attributes and data of the interim table. The original table is locked briefly during this procedure.

Syntax

DBMS_REDEFINITION.FINISH_REDEF_TABLE (
   uname       IN VARCHAR2,
   orig_table  IN VARCHAR2,
   int_table   IN VARCHAR2,
   part_name   IN  VARCHAR2 := NULL);

Parameters

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REGISTER_DEPENDENT_OBJECT Procedure

This procedure registers a dependent object (index, trigger, constraint or materialized view log) on the table being redefined and the corresponding dependent object on the interim table.

This can be used to have the same object on each table but with different attributes. For example: for an index, the storage and tablespace attributes could be different but the columns indexed remain the same

Syntax

DBMS_REDEFINITION.REGISTER_DEPEPENDENT_OBJECT(
   uname             IN VARCHAR2,
   orig_table        IN VARCHAR2,
   int_table         IN VARCHAR2,
   dep_type          IN  PLS_INTEGER,
   dep_owner         IN VARCHAR2,
   dep_orig_name     IN VARCHAR2,
   dep_int_name      IN  VARCHAR2);

Parameters

Usage Notes

• Attempting to register an already registered object will raise an error.

• Registering a dependent object will automatically remove that object from DBA_REDEFINITION_ERRORS if an entry exists for that object.

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START_REDEF_TABLE Procedure

Prior to calling this procedure, you must manually create an empty interim table (in the same schema as the table to be redefined) with the desired attributes of the post-redefinition table, and then call this procedure to initiate the redefinition.

Syntax

DBMS_REDEFINITION.START_REDEF_TABLE (
   uname          IN VARCHAR2,
   orig_table     IN VARCHAR2,
   int_table      IN VARCHAR2,
   col_mapping    IN VARCHAR2 := NULL,
   options_flag   IN BINARY_INTEGER := 1,
   orderby_cols   IN VARCHAR2 := NULL,
   part_name     IN  VARCHAR2 := NULL);

Parameters

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SYNC_INTERIM_TABLE Procedure

This procedure keeps the interim table synchronized with the original table.

Syntax

DBMS_REDEFINITION.SYNC_INTERIM_TABLE (
   uname          IN  VARCHAR2,
   orig_table     IN  VARCHAR2,
   int_table      IN  VARCHAR2,
   part_name      IN  VARCHAR2 := NULL);

Parameters

Usage Notes

• This step is useful in minimizing the amount of synchronization needed to be done by the FINISH_REDEF_TABLE Procedure before completing the online redefinition.

• This procedure can be called between long running operations (such as CREATE INDEX) on the interim table to sync it up with the data in the original table and speed up subsequent operations.

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UNREGISTER_DEPENDENT_OBJECT Procedure

This procedure unregisters a dependent object (index, trigger, constraint or materialized view log) on the table being redefined and the corresponding dependent object on the interim table.

Syntax

DBMS_REDEFINITION.UNREGISTER_DEPEPENDENT_OBJECT(
   uname              IN VARCHAR2,
   orig_table        IN VARCHAR2,
   int_table         IN VARCHAR2,
   dep_type          IN PLS_INTEGER,
   dep_owner         IN VARCHAR2,
   dep_orig_name     IN VARCHAR2,
   dep_int_name      IN  VARCHAR2);

Parameters