56 DBMS_LOGSTDBY

The DBMS_LOGSTDBY package provides subprograms for configuring and managing the logical standby database environment.

See Also:

Oracle Data Guard Concepts and Administration for more information about SQL Apply and logical standby databases

This chapter contains the following topics:

Using DBMS_LOGSTDBY

This section contains topics which relate to using the DBMS_LOGSTDBY package.

Overview

The DBMS_LOGSTDBY package helps you manage the SQL Apply (logical standby database) environment. The subprograms in the DBMS_LOGSTDBY package help you to accomplish the following main objectives:

  • Manage configuration parameters used by SQL Apply.

    For example, controlling how transactions are applied on the logical standby database, how much shared pool is used, and how many processes are used by SQL Apply to mine and apply the changes.

  • Ensure an appropriate level of supplemental logging is enabled, and a LogMiner dictionary is built correctly for logical standby database creation.

  • Provide a way to skip the application of changes to selected tables or entire schemas in the logical standby database, and specify ways to handle exceptions encountered by SQL Apply.

  • Allow controlled access to tables in the logical standby database that may require maintenance.

Operational Notes

Case Sensitivity

Ensure you use the correct case when supplying schema and table names to the DBMS_LOGSTDBY package. For example, the following statements show incorrect and correct syntax for a SKIP procedure that skips changes to OE.TEST.

Incorrect statement:

EXECUTE DBMS_LOGSTDBY.SKIP (stmt => 'DML', schema_name => 'oe', -   object_name => 'test', proc_name => null);

Because the names are specified with lowercase characters, the transactions that update these columns will still be applied to the logical standby database.

Correct statement:

EXECUTE DBMS_LOGSTDBY.SKIP (stmt => 'DML', schema_name => 'OE', -   object_name => 'TEST', proc_name => null);

Privileges and Security

A prototype role, LOGSTDBY_ADMINISTRATOR, is created by default with RESOURCE, and EXECUTE on DBMS_LOGSTDBY privileges. If you choose to use this role, consider granting ALTER DATABASE and ALTER SESSION privileges to the role so that the grantee can start and stop SQL Apply and can enable and disable the database guard. Oracle recommends using an account with DBA privileges to perform administration tasks on logical standby databases.

The six procedures associated with skipping transactions (SKIP and UNSKIP, SKIP_ERROR and UNSKIP_ERROR, and SKIP_TRANSACTION and UNSKIP_TRANSACTION) all require DBA privileges to execute because their scope may contain wildcard schemas. Oracle recommends that where SKIP procedures are specified, these be owned by a secure account with appropriate privileges on the schemas they act on (for example, SYS).

Deprecated Subprograms

The transaction_consistency parameter of the APPLY_SET Procedure is being deprecated with this release of the Oracle Database. The transaction_consistency parameter is being replaced by the preserve_commit_order parameter.

Summary of DBMS_LOGSTDBY Subprograms

Table 56-1 DBMS_LOGSTDBY Package Subprograms

Subprogram Description

APPLY_SET Procedure

Sets the values of various parameters that configure and maintain SQL Apply

APPLY_UNSET Procedure

Restores the default values of various parameters that configure and maintain SQL Apply

BUILD Procedure

Ensures supplemental logging is enabled properly and builds the LogMiner dictionary

INSTANTIATE_TABLE Procedure

Creates and populates a table in the standby database from a corresponding table in the primary database

PREPARE_FOR_NEW_PRIMARY Procedure

Used after a failover, this procedure ensures a local logical standby database that was not involved in the failover has not processed more redo than the new primary database and reports the set of archive redo log files that must be replaced to ensure consistency

PURGE_SESSION Procedure

Identifies the archived redo log files that have been applied to the logical standby database and are no longer needed by SQL Apply

REBUILD Procedure

Records relevant metadata (including the LogMiner Multiversioned Data Dictionary) in the redo stream in case a database that has recently changed its role to a primary database following a failover operation fails to do so during the failover process

SET_TABLESPACE Procedure

Moves metadata tables required by SQL Apply to the user-specified tablespace. By default, the metadata tables are created in the SYSAUX tablespace.

SKIP Procedure

Specifies rules that control database operations that should not be applied to the logical standby database

SKIP_ERROR Procedure

Specifies rules regarding what action to take upon encountering errors

SKIP_TRANSACTION Procedure

Specifies transactions that should not be applied on the logical standby database. Be careful in using this procedure, because not applying specific transactions may cause data corruption at the logical standby database.

UNSKIP Procedure

Deletes rules specified by the SKIP procedure

UNSKIP_ERROR Procedure

Deletes rules specified by the SKIP_ERROR procedure

UNSKIP_TRANSACTION Procedure

Deletes rules specified by the SKIP_TRANSACTION procedure

APPLY_SET Procedure

Use this procedure to set values of parameters that configure and manage SQL Apply in a logical standby database environment. SQL Apply cannot be running when you use this procedure.

Syntax

DBMS_LOGSTDBY.APPLY_SET (
     parameter          IN VARCHAR,
     value              IN VARCHAR);

Parameters

Table 56-2 APPLY_SET Procedure Parameters

Parameter Description

LOG_AUTO_DELETE

Automatically deletes archived redo log files once they have been applied on the logical standby database. Set to TRUE to enable automatic deletion of archived redo log files, and FALSE to disable automatic deletion.The default value is TRUE.

MAX_SGA

Number of megabytes from shared pool in System Global Area (SGA) that SQL Apply will use. The default value is 30 megabytes or one quarter of the value set for SHARED_POOL_SIZE, whichever is lower.

MAX_SERVERS

Number of parallel query servers that SQL Apply uses to read and apply redo. It defaults to the value of the PARALLEL_MAX_SERVERS initialization parameter or 9, whichever is lower.

MAX_EVENTS_RECORDED

Number of recent events that will be visible through the DBA_LOGSTDBY_EVENTS view. To record all events encountered by SQL Apply, use the DBMS_LOGSTDBY.MAX_EVENTS constant as the number value.

PRESERVE_COMMIT_ORDER

TRUE: Transaction are applied to the logical standby database in the exact order in which they were committed on the primary database. This is the default parameter setting.

FALSE: Transactions are applied out of order from how they were committed on the primary database, and no attempt is made to provide read-consistent results.

Regardless of the level chosen, modifications done to the same row are always applied in the same order as they happened in the primary database. See the Usage Notes for details and recommendations.

RECORD_SKIP_ERRORS

Controls whether skipped errors (as described by the SKIP_ERROR procedure) are recorded in the DBA_LOGSTDBY_EVENTS table and the alert log. Specify one of the following values:

TRUE: Skipped errors are recorded in the DBA_LOGSTDBY_EVENTS table and the alert log. This is the default parameter setting.

FALSE: Skipped errors are not recorded in the DBA_LOGSTDBY_EVENTS table and the alert log.

RECORD_SKIP_DDL

Controls whether skipped DDL statements are recorded in the DBA_LOGSTDBY_EVENTS table and the alert log. Specify one of the following values:

TRUE: Skipped DDL statements are recorded in the DBA_LOGSTDBY_EVENTS table and the alert log. This is the default parameter setting.

FALSE: Skipped DDL statements are not recorded in the DBA_LOGSTDBY_EVENTS table and the alert log.

RECORD_APPLIED_DDL

Controls whether DDL statements that have been applied to the logical standby database are recorded in the DBA_LOGSTDBY_EVENTS table and the alert log. Specify one of the following values:

TRUE: Indicates that DDL statements applied to the logical standby database are recorded in the DBA_LOGSTDBY_EVENTS table and the alert log.

FALSE: Indicates that applied DDL statements are not recorded. This is the default parameter setting.

APPLY_SERVERS

Controls the number of APPLIER processes (parallel execution servers) used to apply changes

PREPARE_SERVERS

Controls the number of PREPARER processes (parallel execution servers) used to prepare changes

Exceptions

Table 56-3 APPLY_SET Procedure Exceptions

Exception Description

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

ORA-16236

Logical Standby metadata operation in progress

Usage Notes

  • SQL Apply must be stopped before calling the APPLY_SET procedure.

  • Use the APPLY_UNSET procedure to restore the default settings of a parameter.

  • See Oracle Data Guard Concepts and Administration for help with tuning SQL Apply and for information about setting appropriate values for different parameters.

Examples

To record DDLs in the DBA_LOGSTDBY_EVENTS view and in the alert log, issue the following statement:

SQL> EXECUTE DBMS_LOGSTDBY.APPLY_SET('RECORD_APPLIED_DDL', TRUE);

APPLY_UNSET Procedure

Use the APPLY_UNSET procedure to restore the default values of the parameters that you changed with the APPLY_SET procedure.

Syntax

DBMS_LOGSTDBY.APPLY_UNSET (
     parameter          IN VARCHAR);

Parameters

The parameter information for the APPLY_UNSET procedure is the same as that described for the APPLY_SET procedure. See Table 56-2 for complete parameter information.

Exceptions

Table 56-4 APPLY_UNSET Procedure Exceptions

Exception Description

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

ORA-16236

Logical Standby metadata operation in progress

Usage Notes

  • SQL Apply must be stopped before calling the APPLY_UNSET procedure.

  • Use the APPLY_SET procedure to specify a nondefault value for a parameter.

Examples

If you previously specified that applied DDLs show up in the DBA_LOGSTDBY_EVENTS view and the alert log, you can restore the default behavior of SQL Apply regarding applied DDL statements with the following statement:

SQL> EXECUTE DBMS_LOGSTDBY.APPLY_UNSET('RECORD_APPLIED_DDL');

BUILD Procedure

Use this procedure on the primary database to record relevant metadata (LogMiner dictionary) information in the redo log, which will subsequently be used by SQL Apply. This procedure will enable database-wide primary- and unique-key supplemental logging, if necessary.

Syntax

DBMS_LOGSTDBY.BUILD;

Usage Notes

  • Supplemental log information includes extra information in the redo logs that uniquely identifies a modified row in the logical standby database, and also includes information that helps efficient application of changes to the logical standby database.

  • LogMiner dictionary information allows SQL Apply to interpret data in the redo logs.

  • DBMS_LOGSTDBY.BUILD should be run only once for each logical standby database you want to create. You do not need to use DBMS_LOGSTDBY.BUILD for each RAC instance.

Examples

To build the LogMiner dictionary in the redo stream of the primary database and to record additional information so that a logical standby database can be instantiated, issue the following SQL statement at the primary database

SQL> EXECUTE DBMS_LOGSTDBY.BUILD;

INSTANTIATE_TABLE Procedure

This procedure creates and populates a table in the standby database from a corresponding table in the primary database. The table requires the name of the database link (dblink) as an input parameter. If the table already exists in the logical standby database, it will be dropped and re-created based on the table definition at the primary database. This procedure only brings over the data associated with the table, and not the associated indexes and constraints.

Use the INSTANTIATE_TABLE procedure to:

  • Add a table to a standby database.

  • Re-create a table in a standby database.

Syntax

DBMS_LOGSTDBY.INSTANTIATE_TABLE (
     schema_name         IN VARCHAR2,
     table_name          IN VARCHAR2,
     dblink              IN VARCHAR2);

Parameters

Table 56-5 INSTANTIATE_TABLE Procedure Parameters

Parameter Description

schema_name

Name of the schema

table_name

Name of the table to be created or re-created in the standby database

dblink

Name of the database link account that has privileges to read and lock the table in the primary database

Exceptions

Table 56-6 INSTANTIATE_TABLE Procedure Exceptions

Exception Description

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16236

Logical Standby metadata operation in progress

Usage Notes

  • Use this procedure to create and populate a table in a way that keeps the data on the standby database transactionally consistent with the primary database.

  • This table will not be synchronized with the rest of the tables being maintained by SQL Apply and SQL Apply will not start to maintain it until the redo log that was current on the primary database at the time of execution is applied to the standby database.

Examples

SQL> EXECUTE DBMS_LOGSTDBY.INSTANTIATE_TABLE (-
     SCHEMA_NAME => 'HR', TABLE_NAME => 'EMPLOYEES', -
     DBLINK => 'INSTANTIATE_TBL_LINK');

PREPARE_FOR_NEW_PRIMARY Procedure

The PREPARE_FOR_NEW_PRIMARY procedure must be invoked at a logical standby database following a failover if that standby database was not the target of the failover operation. Such a standby database must process the exact same set of redo logs processed at the new primary database. This routine ensures that the local logical standby database has not processed more redo than the new primary database and reports the set of archive logs that must be replaced to ensure consistency. The set of replacement logs will be reported in the alert.log. These logs must be copied to the logical standby and registered using the ALTER DATABASE REGISTER LOGICAL LOGFILE statement.

Syntax

DBMS_LOGSTDBY.PREPARE_FOR_NEW_PRIMARY (
           FORMER_STANDBY_TYPE         IN VARCHAR2,
           DBLINK                      IN VARCHAR2);

Parameters

Table 56-7 PREPARE_FOR_NEW_PRIMARY Procedure Parameters

Parameter Description

FORMER_STANDBY_TYPE

The type of standby database that was the target of the failover operation to become the new primary database. Valid values are 'PHYSICAL' if the new primary was formerly a physical standby, and 'LOGICAL' if the new primary database was formerly a logical standby database.

DBLINK

The name of a database link to the new primary database

Exceptions

Table 56-8 PREPARE_FOR_NEW_PRIMARY Procedure Exceptions

Exception Description

ORA-16104

Invalid Logical Standby option.

ORA-16109

Failed to apply log data from previous primary.

Usage Notes

  • This routine is intended only for logical standby systems.This routine will fail if the new primary database was formerly a logical standby database and the LogMiner dictionary build has not completed successfully.Log files displayed in the alert log will be referred to as terminal logs. Users should keep in mind that file paths are relative to the new primary database and may not resolve locally.Upon manual registration of the terminal logs, users should complete the process by calling either START LOGICAL STANDBY APPLY if the new primary database was formerly a physical standby database or START LOGICAL STANDBY APPLY NEW PRIMARY if the new primary database was formerly a logical standby database.See the alert log for more details regarding the reasons for any exception.

Examples

SQL> EXECUTE DBMS_LOGSTDBY.PREPARE_FOR_NEW_PRIMARY (  -
                FORMER_STANDBY_TYPE => 'LOGICAL',    -
                DBLINK => 'dblink_to_newprimary');

PURGE_SESSION Procedure

Identifies all archived redo log files that have been applied to the logical standby database and are no longer needed by SQL Apply. Once identified, you can issue operating system commands to delete some or all of the unnecessary archived redo log files.

Syntax

DBMS_LOGSTDBY.PURGE_SESSION;

Exceptions

Table 56-9 PURGE_SESSION Procedure Exceptions

Exception Description

ORA-01309

Invalid session

Usage Notes

  • This procedure does not delete the archived redo log files. You must issue operating system commands to delete unneeded files.

  • This procedure updates the DBA_LOGMNR_PURGED_LOG view that displays the archived redo log files that have been applied to the logical standby database.

  • In Oracle Database 10g Release 2, metadata related to the archived redo log files (and the actual archived redo log files) are purged automatically based on the default setting of the LOG_AUTO_DELETE parameter described in the DBMS_LOGSTDBY.APPLY_SET procedure described.

Example

To identify and remove unnecessary files:

  1. Enter the following statement on the logical standby database:

    SQL> EXECUTE DBMS_LOGSTDBY.PURGE_SESSION;

  1. Query the DBA_LOGMNR_PURGED_LOG view to list the archived redo log files that can be removed:

    SQL> SELECT * FROM DBA_LOGMNR_PURGED_LOG;

FILE_NAME
   ------------------------------------
   /boston/arc_dest/arc_1_40_509538672.log
   /boston/arc_dest/arc_1_41_509538672.log
   /boston/arc_dest/arc_1_42_509538672.log
   /boston/arc_dest/arc_1_43_509538672.log
   /boston/arc_dest/arc_1_44_509538672.log
   /boston/arc_dest/arc_1_45_509538672.log
   /boston/arc_dest/arc_1_46_509538672.log
   /boston/arc_dest/arc_1_47_509538672.log

  1. Use operating system-specific commands to delete archived redo log files from the file system.

REBUILD Procedure

This procedure is used if a database that has recently changed its role to a primary database following a failover operation fails to record relevant metadata (including the LogMiner Multiversioned Data Dictionary) in the redo stream required for other logical standby databases.

Syntax

DBMS_LOGSTDBY.REBUILD;

Usage Notes

  • LogMiner Multiversioned Data Dictionary information is logged in the redo log files.The standby redo log files (if present) are archived.

Examples

SQL> EXECUTE DBMS_LOGSTDBY.REBUILD;

SET_TABLESPACE Procedure

Moves metadata tables required by SQL Apply to the user-specified tablespace. By default, the metadata tables are created in the SYSAUX tablespace.

Syntax

DBMS_LOGSTDBY.SET_TABLESPACE(
           NEW_TABLESPACE IN VARCHAR2)

Parameters

Table 56-10 SET_TABLE SPACE Procedure Parameters

Parameter Description

NEW_TABLESPACE

Name of the new tablespace where metadata tables will reside.

Exceptions

Table 56-11 SET_TABLESPACE Procedure Exceptions

Exception Description

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16236

Logical Standby metadata operation in progress

Examples

To move metadata tables to a new tablespace named LOGSTDBY_TBS, issue the following statement:

SQL> EXECUTE DBMS_LOGSTDBY.SET_TABLESPACE (new_tablespace => 'LOGSTDBY_TBS');

SKIP Procedure

The SKIP procedure can be used to define rules that will be used by SQL Apply to skip the application of certain changes to the logical standby database. For example, the SKIP procedure can be used to skip changes to a subset of tables in the logical standby database. It can also be used to specify DDL statements that should not be applied at the logical standby database or should be modified before they are applied in the logical standby database. One reason why a DDL statement may need to be modified is to accommodate a different directory structure on the logical standby database.

Syntax

DBMS_LOGSTDBY.SKIP (
     stmt                      IN VARCHAR2,
     schema_name               IN VARCHAR2 DEFAULT NULL,
     object_name               IN VARCHAR2 DEFAULT NULL,
     proc_name                 IN VARCHAR2 DEFAULT NULL,
     use_like                  IN BOOLEAN DEFAULT TRUE,
     esc                       IN CHAR1 DEFAULT NULL);

Parameters

Table 56-12 SKIP Procedure Parameters

Parameter Description

stmt

Either a keyword that identifies a set of SQL statements or a specific SQL statement. The use of keywords simplifies configuration since keywords, generally defined by the database object, identify all SQL statements that operate on the specified object. Table 56-13 shows a list of keywords and the equivalent SQL statements, either of which is a valid value for this parameter.

schema_name

The name of one or more schemas (wildcards are permitted) associated with the SQL statements identified by the stmt parameter. If not applicable, this value must be set to NULL.

object_name

The name of one or more objects (wildcards are permitted) associated with the SQL statements identified by the stmt. If not applicable, this value must be set to NULL.

proc_name

Name of a stored procedure to call when SQL Apply determines that a particular statement matches the filter defined by the stmt, schema_name, and object_name parameters. Specify the procedure in the following format:

'"schema"."package"."procedure"'

This procedure returns a value that directs SQL Apply to perform one of the following: execute the statement, skip the statement, or execute a replacement statement.

SQL Apply calls the stored procedure with the following call signature:

  • IN STATEMENT VARCHAR2 -- The SQL statement that matches the filter

  • IN STATEMENT_TYPE VARCHAR2 -- The stmt of the filter

  • IN SCHEMA VARCHAR2 -- The schema_name of the filter, if applicable

  • IN NAME VARCHAR2 -- The object_name of the filter, if applicable

  • IN XIDUSN NUMBER -- Transaction ID part 1

  • IN XIDSLT NUMBER -- Transaction ID part 2

  • IN XIDSQN NUMBER -- Transaction ID part 3

  • OUT SKIP_ACTION NUMBER -- Action to be taken by SQL Apply upon completion of this routine. Valid values are:

    SKIP_ACTION_APPLY -- Execute the statement

    SKIP_ACTION_SKIP -- Skip the statement

    SKIP_ACTION_REPLACE -- Execute the replacement statement supplied in the NEW_STATEMENT output parameter

use_like

Allows pattern matching to isolate the tables that you want to skip on the logical standby database. The use_like parameter matches a portion of one character value to another by searching the first value for the pattern specified by the second, and calculates strings using characters as defined by the input character set. This parameter follows the same rules for pattern matching described in the Oracle Database SQL Reference.

esc

Identifies an escape character (such as the character "/") that you can use for pattern matching. If the escape character appears in the pattern before the character "%" or "_" then Oracle interprets this character literally in the pattern, rather than as a special pattern matching character. SeeOracle Database SQL Reference for more information about pattern matching.

Usage Notes

  • This procedure requires DBA privileges to execute.

  • You cannot associate a stored procedure to be invoked in the context of a DML statement. For example, the following statement returns the ORA-16104: invalid Logical Standby option requested error:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP(-
     stmt => 'DML', -
     schema_name => 'HR', -
     object_name => 'EMPLOYEES', -
     proc_name => 'DML_HANDLER');

    Also, if an event matches multiple rules either because of the use of wildcards while specifying the rule or because of a specification of overlapping rules. For example, if you specify a rule for the SCHEMA_DDL event for the HR.EMPLOYEES table, and a rule for the ALTER TABLE event for the HR.EMPLOYEES table, only one of the matching procedures will be invoked (alphabetically, by procedure). In the following code example, consider the following rules:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP( -
     stmt => 'SCHEMA DDL', -
     schema_name => 'HR', -
     object_name => 'EMPLOYEES', -
     proc_name => 'SCHEMA_DDL_HANDLER');
SQL> EXECUTE DBMS_LOGSTDBY.SKIP( -
     stmt => 'ALTER TABLE', -
     schema_name => 'HR', -
     object_name => 'EMPLOYEES', -
     proc_name => 'TABLE_ALTER_HANDLER');

    On encountering an ALTER TABLE statement, the schema_ddl_handler procedure will be invoked because its name will be at the top of an alphabetically sorted list of procedures that are relevant to the statement.Collisions on a rule set because of a specification containing wildcard entries are resolved in a similar fashion. For example, the rules in the following example will result in the empddl_handler procedure being invoked upon encountering the ALTER TABLE HR.EMPLOYEES ADD COLUMN RATING NUMBER statement:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP(-
     stmt => 'ALTER TABLE', -
     schema_name => 'HR', -
     object_name => 'EMP%', -
     proc_name => 'EMPDDL_HANDLER');
SQL> EXECUTE DBMS_LOGSTDBY.SKIP( -
     stmt => 'ALTER TABLE', -
     schema_name => 'HR', -
     object_name => 'EMPLOYEES', -
     proc_name => 'EMPLOYEE_DDL_HANDLER');

  • Use the SKIP procedure with caution, particularly when skipping DDL statements. If a CREATE TABLE statement is skipped, for example, you must also specify other DDL statements that refer to that table in the SKIP procedure. Otherwise, the statements will fail and cause an exception. When this happens, SQL Apply stops running.

  • Before calling the SKIP procedure, SQL Apply must be halted. Do this by issuing an ALTER DATABASE STOP LOGICAL STANDBY APPLY statement. Once all desired filters have been specified, issue an ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATE statement to start SQL Apply using the new filter settings.

  • See the UNSKIP procedure for information about reversing (undoing) the settings of the SKIP procedure.

  • For USER statements, the SCHEMA_NAME parameter will be the user and specify '%' for the OBJECT_NAME parameter.

  • If the PROC_NAME parameter is supplied, it must already exist in DBA_PROCEDURES and it must execute with DEFINER rights. If the procedure is declared with INVOKER rights, the ORA-1031: insufficient privileges message will be returned.

  • If the procedure returns a REPLACEMENT statement, the REPLACEMENT statement will be executed using the SYSTEM and OBJECT privileges of the owner of the procedure.

  • The PL/SQL block of a SKIP procedure cannot contain transaction control statements (for example, COMMIT, ROLLBACK, SAVEPOINT, and SET CONSTRAINT) unless the block is declared to be an autonomous transaction.

Skip Statement Options

Table 56-13 lists the supported values for the stmt parameter of the SKIP procedure. The left column of the table lists the keywords that may be used to identify the set of SQL statements to the right of the keyword. Any of the SQL statements in the right column, however, are also valid values. Note that keywords are generally defined by database object.

Table 56-13 Supported Values for the stmt Parameter

Keyword Associated SQL Statements

NON_SCHEMA_DDL

All DDL that does not pertain to a particular schema

Note: SCHEMA_NAME and OBJECT_NAME must be null

SCHEMA_DDL

All DDL statements that create, modify, or drop schema objects (for example: tables, indexes, and columns)

Note: SCHEMA_NAME and OBJECT_NAME must not be null

DML

Includes DML statements on a table (for example: INSERT, UPDATE, and DELETE)

CLUSTER

 
AUDIT CLUSTER
CREATE CLUSTER
DROP CLUSTER
TRUNCATE CLUSTER

CONTEXT

 
CREATE CONTEXT
DROP CONTEXT

DATABASE LINK

 
CREATE DATABASE LINK
CREATE PUBLIC DATABASE LINK
DROP DATABASE LINK
DROP PUBLIC DATABASE LINK

DIMENSION

 
ALTER DIMENSION
CREATE DIMENSION
DROP DIMENSION

DIRECTORY

 
CREATE DIRECTORY
DROP DIRECTORY

INDEX

 
ALTER INDEX
CREATE INDEX
DROP INDEX

PROCEDUREFoot 1 

 
ALTER FUNCTION
ALTER PACKAGE
ALTER PACKAGE BODY
ALTER PROCEDURE
CREATE FUNCTION
CREATE LIBRARY
CREATE PACKAGE
CREATE PACKAGE BODY
CREATE PROCEDURE
DROP FUNCTION
DROP LIBRARY
DROP PACKAGE
DROP PACKAGE BODY
DROP PROCEDURE

PROFILE

 
ALTER PROFILE
CREATE PROFILE
DROP PROFILE

ROLE

 
ALTER ROLE
CREATE ROLE
DROP ROLE
SET ROLE

ROLLBACK STATEMENT

 
ALTER ROLLBACK SEGMENT
CREATE ROLLBACK SEGMENT
DROP ROLLBACK SEGMENT

SEQUENCE

 
ALTER SEQUENCE
CREATE SEQUENCE
DROP SEQUENCE

SYNONYM

 
CREATE PUBLIC SYNONYM
CREATE SYNONYM
DROP PUBLIC SYNONYM
DROP SYNONYM

TABLE

 
ALTER TABLE
CREATE TABLE
DROP TABLE

TABLESPACE

 
CREATE TABLESPACE
DROP TABLESPACE
TRUNCATE TABLESPACE

TRIGGER

 
ALTER TRIGGER
CREATE TRIGGER
DISABLE ALL TRIGGERS
DISABLE TRIGGER
DROP TRIGGER
ENABLE ALL TRIGGERS
ENABLE TRIGGER

TYPE

 
ALTER TYPE
ALTER TYPE BODY
CREATE TYPE
CREATE TYPE BODY
DROP TYPE
DROP TYPE BODY

USER

 
ALTER USER
CREATE USER
DROP USER

VIEW

 
CREATE VIEW
DROP VIEW

Footnote 1 Java schema objects (sources, classes, and resources) are considered the same as procedure for purposes of skipping (ignoring) SQL statements.

Exceptions

Table 56-14 DBMS_LOGSTDBY.SKIP Procedure Exceptions

Exception Description

ORA-01031

Insufficient privileges:

  • Procedure used INVOKER rights

  • Procedure needs DBA privileges

ORA-16103

Logical standby apply must be stopped to allow this operation.

ORA-16104

Invalid logical standby option requested.

ORA-16203

"Unable to interpret SKIP procedure return values."

Indicates that a SKIP procedure has either generated an exception or has returned ambiguous values. You can identify the offending procedure by examining the DBA_LOGSTDBY_EVENTS view.

ORA-16236

Logical standby metadata operation in progress.

Examples


Example 1   Skipping all DML and DDL changes made to a schema

The following example shows how to specify rules so that SQL Apply will skip both DDL and DML statements made to the HR schema.

SQL> EXECUTE DBMS_LOGSTDBY.SKIP(STMT => 'SCHEMA DDL', -
     schema_name => 'HR', -
     table_name => '%', -
     proc_name => null);
SQL> EXECUTE DBMS_LOGSTDBY.SKIP(STMT => 'DML', -
     schema_name => 'HR', -
     table_name => '%', -
     proc_name => null);

Example 2   Creating a procedure to handle different file system organization

For example, if the file system organization in the logical standby database is different than that in the primary database, you can write a SKIP procedure to handle DDL statements with file specifications transparently.The following procedure can handle DDL statements as long as you follow a specific naming convention for the file specification string.

  1. Create the SKIP procedure to handle tablespace DDL statements:

    CREATE OR REPLACE PROCEDURE sys.handle_tbs_ddl (

  old_stmt  IN  VARCHAR2,
  stmt_typ  IN  VARCHAR2,
  schema    IN  VARCHAR2,
  name      IN  VARCHAR2,
  xidusn    IN  NUMBER,
  xidslt    IN  NUMBER,
  xidsqn    IN  NUMBER,
  action    OUT NUMBER,
  new_stmt  OUT VARCHAR2
) AS
BEGIN
 
-- All primary file specification that contains a directory
-- /usr/orcl/primary/dbs
-- should go to /usr/orcl/stdby directory specification
 
 
  new_stmt = replace(old_stmt,
                     '/usr/orcl/primary/dbs',
                     '/usr/orcl/stdby');
 
  action := DBMS_LOGSTDBY.SKIP_ACTION_REPLACE;
 
EXCEPTION
  WHEN OTHERS THEN
    action := DBMS_LOGSTDBY.SKIP_ACTION_ERROR;
    new_stmt := NULL;
END handle_tbs_ddl;

  2. Register the SKIP procedure with SQL Apply:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP (stmt => 'TABLESPACE', -
             proc_name => 'SYS.HANDLE_TBS_DDL');

SKIP_ERROR Procedure

Upon encountering an error, the logical standby database uses the criteria contained in this procedure to determine if the error should cause SQL Apply to stop. All errors to be skipped are stored in system tables that describe how exceptions should be handled.

Syntax

DBMS_LOGSTDBY.SKIP_ERROR (
     stmt                      IN VARCHAR2,
     schema_name               IN VARCHAR2,
     object_name               IN VARCHAR2,
     proc_name                 IN VARCHAR2,
     use_like                  IN BOOLEAN,
     esc                       IN CHAR1);

Parameters

Table 56-15 SKIP_ERROR Procedure Parameters

Parameter Description

stmt

Either a keyword that identifies a set of SQL statements or a specific SQL statement. The use of keywords simplifies configuration because keywords, generally defined by the database object, identify all SQL statements that operate on the specified object. Table 56-13 shows a list of keywords and the equivalent SQL statements, either of which is a valid value for this parameter.

schema_name

The name of one or more schemas (wildcards are permitted) associated with the SQL statements identified by the stmt parameter. If not applicable, this value must be set to NULL.

object_name

The name of one or more objects (wildcards are permitted) associated with the SQL statements identified by the stmt. If not applicable, this value must be set to NULL.

proc_name

Name of a stored procedure to call when SQL Apply determines a particular statement matches the filter defined by the stmt, schema_name, and object_name parameters. Specify the procedure in the following format:

'"schema"."package"."procedure"'

This procedure returns a value that directs SQL Apply to perform one of the following: execute the statement, skip the statement, or execute a replacement statement.

SQL Apply calls the stored procedure with the following call signature:

  • IN STATEMENT VARCHAR(4000) -- The first 4K of the statement

  • IN STATEMENT_TYPE VARCHAR2 -- The stmt of the filter

  • IN SCHEMA VARCHAR2 -- The schema_name of the filter, if applicable

  • IN NAME VARCHAR2 -- The object_name of the filter, if applicable

  • IN XIDUSN NUMBER -- Transaction ID part 1

  • IN XIDSLT NUMBER -- Transaction ID part 2

  • IN XIDSQN NUMBER -- Transaction ID part 3

  • IN ERROR VARCHAR(4000) -- Text of error to be recorded (optional)

  • OUT NEW_ERROR VARCHAR(4000) -- Null or modified error text

use_like

Allows pattern matching to isolate the tables that you want to skip on the logical standby database. The use_like parameter matches a portion of one character value to another by searching the first value for the pattern specified by the second, and calculates strings using characters as defined by the input character set. This parameter follows the same rules for pattern matching described in the Oracle Database SQL Reference.

esc

Identifies an escape character (such as the characters "%" or "_") that you can use for pattern matching. If the escape character appears in the pattern before the character "%" or "_" then Oracle interprets this character literally in the pattern, rather than as a special pattern matching character. SeeOracle Database SQL Reference for more information about pattern matching.

Usage Notes

  • A stored procedure provided to the SKIP_ERROR procedure is called when SQL Apply encounters an error that could shut down the application of redo logs to the standby database.

  • Running this stored procedure affects the error being written in the STATUS column of the DBA_LOGSTDBY_EVENTS table. The STATUS_CODE column remains unchanged. If the stored procedure is to have no effect, that is, apply will be stopped, then the NEW_ERROR is written to the events table. To truly have no effect, set NEW_ERROR to ERROR in the procedure.

  • If the stored procedure requires that a shutdown be avoided, then you must set NEW_ERROR to NULL.

  • This procedure requires DBA privileges to execute.

  • For USER statements, the SCHEMA_NAME parameter will be the user and you should specify '%' for the OBJECT_NAME parameter.

  • If the PROC_NAME parameter is specified, it must already exist in DBA_PROCEDURES and it must execute with DEFINERS rights. If the procedure is declared with INVOKERS rights, the ORA-1031: insufficient privileges message will be returned.

  • The PL/SQL block of a SKIP_ERROR procedure cannot contain transaction control statements (for example: COMMIT, ROLLBACK, SAVEPOINT, and SET CONSTRAINT) unless the block is declared to be an autonomous transaction using the following syntax:

    PRAGMA AUTONOMOUS_TRANSACTION

Exceptions

Table 56-16 SKIP_ERROR Procedure Exceptions

Exception Description

ORA-01031

Insufficient privileges:

  • Procedure used INVOKER rights

  • Procedure needs DBA privileges

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

ORA-16236

Logical Standby metadata operation in progress

Examples

To skip errors on GRANT statements on SYS or HR schemas, define a procedure handle_error_ddl and register it. In the following example, assume that handle_error_ddl is a free-standing procedure in the SYS schema.

  1. Create the error-handler procedure:

    CREATE OR REPLACE PROCEDURE sys.handle_error_ddl (
  old_stmt    IN  VARCHAR2,
  stmt_type   IN  VARCHAR2,
  schema      IN  VARCHAR2,
  name        IN  VARCHAR2,
  xidusn      IN  NUMBER,
  xidslt      IN  NUMBER,
  xidsqn      IN  NUMBER,
  error       IN  VARCHAR2,
  new_stmt    OUT VARCHAR2
) AS

BEGIN
  -- Default to what we already have
  new_stmt := old_stmt;

  -- Ignore any GRANT errors on SYS or HR schemas
  IF INSTR(UPPER(old_stmt),'GRANT') > 0
  THEN
    IF schema IS NULL
    OR (schema IS NOT NULL AND
          (UPPER(schema) = 'SYS'  OR UPPER(schema) = 'HR' )
    THEN
      new_stmt := NULL;
      -- record the fact that we just skipped an error on 'SYS' or 'HR' schemas
      -- code not shown here
    END IF;
  END IF;

END handle_error_ddl;
/

  2. Register the error handler with SQL Apply:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP_ERROR ( -
     statement => 'NON_SCHEMA_DDL', -
     schema_name => NULL, -
     object_name => NULL, -
     proc_name => 'SYS.HANDLE_ERROR_DDL');

SKIP_TRANSACTION Procedure

This procedure provides a way to skip (ignore) applying transactions to the logical standby database. You can skip specific transactions by specifying transaction identification information.

Syntax

DBMS_LOGSTDBY.SKIP_TRANSACTION (
     XIDUSN                 IN NUMBER,
     XIDSLT NUMBER          IN NUMBER,
     XIDSQN NUMBER          IN NUMBER);

Parameters

Table 56-17 SKIP_TRANSACTION Procedure Parameters

Parameter Description

XIDUSN NUMBER

Transaction ID undo segment number of the transaction being skipped

XIDSLT NUMBER

Transaction ID slot number of the transaction being skipped

XIDSQN NUMBER

Transaction ID sequence number of the transaction being skipped

Usage Notes

If SQL Apply stops due to a particular transaction (for example, a DDL transaction), you can specify that transaction ID and then continue to apply. You can call this procedure multiple times for as many transactions as you want SQL Apply to ignore.

CAUTION:

SKIP_TRANSACTION is an inherently dangerous operation. Do not invoke this procedure unless you have examined the transaction in question through the V$LOGMNR_CONTENTS view and have taken compensating actions at the logical standby database. SKIP_TRANSACTION is not the appropriate procedure to invoke to skip DML changes to a table.

To skip a DML failure, use a SKIP procedure, such as SKIP('DML','MySchema','MyFailed Table'). Using the SKIP_TRANSACTION procedure for DML transactions may skip changes for other tables, thus logically corrupting them.

  • This procedure requires DBA privileges to execute.

  • Use the DBA_LOGSTDBY_SKIP_TRANSACTION view to list the transactions that are going to be skipped by SQL Apply.

  • Also, see the ALTER DATABASE START LOGICAL STANDBY SKIP FAILED TRANSACTION statement in Oracle Database SQL Reference.

Exceptions

Table 56-18 SKIP_TRANSACTION Procedure Exceptions

Exception Description

ORA-01031

Need DBA privileges

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

Examples

To skip a DDL transaction with (XIDUSN, XIDSLT, XIDSQN) of (1.13.1726) you can register a rule as shown in the following example:

SQL> EXECUTE DBMS_LOGSTDBY.SKIP_TRANSACTION (- 
     XIDUSN => 1, XIDSLT => 13, XIDSQN => 1726);

UNSKIP Procedure

Use the UNSKIP procedure to delete rules specified earlier with the SKIP procedure. The parameters specified in the UNSKIP procedure must match exactly for it to delete an already-specified rule.

Syntax

DBMS_LOGSTDBY.UNSKIP (
     stmt                      IN VARCHAR2,
     schema_name               IN VARCHAR2,
     object_name               IN VARCHAR2);

Parameters

The parameter information for the UNSKIP procedure is the same as that described for the SKIP procedure. See Table 56-12 for complete parameter information.

Exceptions

Table 56-19 UNSKIP Procedure Exceptions

Exception Description

ORA-01031

Need DBA privileges

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

Usage Notes

CAUTION:

If DML changes for a table have been skipped and not compensated for, you must follow the call to the UNSKIP procedure with a call to the INSTANTIATE_TABLE procedure to synchronize this table with those maintained by SQL Apply.

  • This procedure requires DBA privileges to execute.

  • Wildcards passed in the schema_name or the object_name parameter are not expanded. The wildcard character is matched at the character level. Thus, you can delete only one specified rule by invoking the UNSKIP procedure, and you will need a distinct UNSKIP procedure call to delete each rule that was previously specified.

    For example, assume you have specified the following two rules to skip applying DML statements to the HR.EMPLOYEE and HR.EMPTEMP tables:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP (STMT => 'DML',-
     SCHEMA_NAME => 'HR', -
     OBJECT_NAME => 'EMPLOYEE', -
     PROC_NAME => null);
SQL> EXECUTE DBMS_LOGSTDBY.SKIP (STMT => 'DML',-
     SCHEMA_NAME => 'HR', -
     OBJECT_NAME => 'EMPTEMP', -
     PROC_NAME => null);

    In the following example, the wildcard in the TABLE_NAME parameter cannot be used to delete the rules that were specified:

    SQL> EXECUTE DBMS_LOGSTDBY.UNSKIP (STMT => 'DML',-
     SCHEMA_NAME => 'HR', -
     OBJECT_NAME => 'EMP%');

    In fact, this UNSKIP procedure matches neither of the rules, because the wildcard character in the TABLE_NAME parameter is not expanded. Instead, the wildcard character will be used in an exact match to find the corresponding SKIP rule.

UNSKIP_ERROR Procedure

Use the UNSKIP_ERROR procedure to delete rules specified earlier with the SKIP_ERROR procedure. The parameters specified in the UNSKIP_ERROR procedure must match exactly for the procedure to delete an already-specified rule.

Syntax

DBMS_LOGSTDBY.UNSKIP_ERROR (
     stmt                      IN VARCHAR2,
     schema_name               IN VARCHAR2,
     object_name               IN VARCHAR2);

Parameters

The parameter information for the UNSKIP_ERROR procedure is the same as that described for the SKIP_ERROR procedure. See Table 56-15 for complete parameter information.

Exceptions

Table 56-20 UNSKIP_ERROR Procedure Exceptions

Exception Description

ORA-01031

Need DBA privileges

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

Usage Notes

  • This procedure requires DBA privileges to execute.

  • Wildcards passed in the schema_name or the object_name parameters are not expanded. Instead, the wildcard character is treated as any other character and an exact match is made. Thus, you can delete only one specified rule by invoking the UNSKIP_ERROR procedure, and you need a distinct UNSKIP_ERROR procedure call to delete each rule that you previously specified.

    For example, assume you have specified the following two rules to handle the HR.EMPLOYEE and HR.EMPTEMP tables:

    SQL> EXECUTE DBMS_LOGSTDBY.SKIP_ERROR (STMT => 'DML',-
     SCHEMA_NAME => 'HR', -
     OBJECT_NAME => 'EMPLOYEE', -
     PROC_NAME => 'hr_employee_handler');
SQL> EXECUTE DBMS_LOGSTDBY.SKIP_ERROR (STMT => 'DML',-
     SCHEMA_NAME => 'HR', -
     OBJECT_NAME => 'EMPTEMP', -
     PROC_NAME => 'hr_tempemp_handler');

    In this case, the following UNSKIP procedure cannot be used to delete the rules that you have specified:

    SQL> EXECUTE DBMS_LOGSTDBY.UNSKIP_ERROR (STMT => 'DML',-
     SCHEMA_NAME => 'HR', -
     OBJECT_NAME => 'EMP%');

    In fact, the UNSKIP procedure will match neither of the rules, because the wildcard character in the OBJECT_NAME parameter will not be expanded.

Example

To remove a handler that was previously registered with SQL Apply from getting called on encountering an error, you can issue the following statement:

DBMS_LOGSTDBY.UNSKIP_ERROR ( -
      statement => 'NON_SCHEMA_DDL', -
      schema_name => NULL, -
      object_name => NULL);

UNSKIP_TRANSACTION Procedure

Use the UNSKIP_TRANSACTION procedure to delete rules specified earlier with the SKIP_TRANSACTION procedure. The parameters specified in the UNSKIP_TRANSACTION procedure must match exactly for the procedure to delete an already-specified rule.

Syntax

DBMS_LOGSTDBY.UNSKIP_TRANSACTION (
     XIDUSN           NUMBER,
     XIDSLT           NUMBER,
     XIDSQN           NUMBER);

Parameters

Table 56-21 UNSKIP_TRANSACTION Procedure Parameters

Parameter Description

XIDUSN

Transaction ID undo segment number of the transaction being skipped

XIDSLT

Transaction ID slot number of the transaction being skipped

XIDSQN

Transaction ID sequence number of the transaction being skipped

Exceptions

Table 56-22 UNSKIP_TRANSACTION Procedure Exceptions

Exception Description

ORA-01031

Need DBA privileges

ORA-16103

Logical Standby apply must be stopped to allow this operation

ORA-16104

invalid Logical Standby option requested

Usage Notes

  • This procedure requires DBA privileges to execute.

  • Query the DBA_LOGSTDBY_SKIP_TRANSACTION view to list the transactions that are going to be skipped by SQL Apply.

Examples

To remove a rule that was originally specified to skip the application of a transaction with (XIDUSN, XIDSLT, XIDSQN) of (1.13.1726) issue the following statement:

SQL> DBMS_LOGSTDBY.UNSKIP_TRANSACTION (XIDUSN => 1, XIDSLT => 13, XIDSQN => 1726);