13 Managing an Apply Process

Examples of Creating an Apply Process Using DBMS_STREAMS_ADM

The first example in this section creates an apply process that applies captured messages. The second example in this section creates an apply process that applies user-enqueued messages. A single apply process cannot apply both captured and user-enqueued messages.

• Creating an Apply Process for Captured Messages

• Creating an Apply Process for User-Enqueued Messages

  See Also:

  • "Apply Process Creation"

  • "System-Created Rules"

  • Oracle Streams Replication Administrator's Guide for more information about Streams tags

BEGIN
  DBMS_STREAMS_ADM.ADD_SCHEMA_RULES(
    schema_name        => 'hr',
    streams_type       => 'apply',
    streams_name       => 'strm01_apply',
    queue_name         => 'streams_queue',
    include_dml        => true,
    include_ddl        => false,
    include_tagged_lcr => false,
    source_database    => 'dbs1.net',
    inclusion_rule     => true);
END;
/

BEGIN
  DBMS_STREAMS_ADM.ADD_MESSAGE_RULE(
    message_type       => 'oe.order_typ',
    rule_condition     => ':msg.order_status = 1',
    streams_type       => 'apply',
    streams_name       => 'strm02_apply',
    queue_name         => 'strm02_queue',
    inclusion_rule     => true);
END;
/

Examples of Creating an Apply Process Using DBMS_APPLY_ADM

The first example in this section creates an apply process that applies captured messages. The second example in this section creates an apply process that applies user-enqueued messages. A single apply process cannot apply both captured and user-enqueued messages.

• Creating an Apply Process for Captured Messages with DBMS_APPLY_ADM

• Creating an Apply Process for User-Enqueued Messages with DBMS_APPLY_ADM

  See Also:

  • "Apply Process Creation"

  • "Message Processing Options for an Apply Process" for more information about apply handlers

  • Oracle Streams Replication Administrator's Guide for more information about Streams tags

  • Oracle Streams Replication Administrator's Guide for information about configuring an apply process to apply messages to a non-Oracle database using the apply_database_link parameter

BEGIN
  DBMS_APPLY_ADM.CREATE_APPLY(
    queue_name             => 'strm03_queue',
    apply_name             => 'strm03_apply',
    rule_set_name          => 'strmadmin.strm03_rule_set',
    message_handler        => NULL,     
    ddl_handler            => 'strmadmin.history_ddl',
    apply_user             => 'hr',
    apply_database_link    => NULL,
    apply_tag              => HEXTORAW('5'),
    apply_captured         => true,
    precommit_handler      => NULL,
    negative_rule_set_name => NULL,
    source_database        => 'dbs1.net');
END;
/

BEGIN
  DBMS_APPLY_ADM.CREATE_APPLY(
    queue_name             => 'strm04_queue',
    apply_name             => 'strm04_apply',
    rule_set_name          => 'strmadmin.strm04_rule_set',
    message_handler        => 'strmadmin.mes_handler',
    ddl_handler            => NULL,
    apply_user             => NULL,
    apply_database_link    => NULL,
    apply_tag              => NULL,
    apply_captured         => false,
    precommit_handler      => NULL,
    negative_rule_set_name => NULL);
END;
/

Specifying the Rule Set for an Apply Process

You can specify one positive rule set and one negative rule set for an apply process. The apply process applies a message if it evaluates to TRUE for at least one rule in the positive rule set and discards a message if it evaluates to TRUE for at least one rule in the negative rule set. The negative rule set is evaluated before the positive rule set.

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name    => 'strm01_apply',
    rule_set_name => 'strmadmin.strm02_rule_set');
END;
/

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name             => 'strm01_apply',
    negative_rule_set_name => 'strmadmin.strm03_rule_set');
END;
/

Adding Rules to the Rule Set for an Apply Process

To add rules to the rule set for an apply process, you can run one of the following procedures:

• DBMS_STREAMS_ADM.ADD_TABLE_RULES

• DBMS_STREAMS_ADM.ADD_SUBSET_RULES

• DBMS_STREAMS_ADM.ADD_SCHEMA_RULES

• DBMS_STREAMS_ADM.ADD_GLOBAL_RULES

Excluding the ADD_SUBSET_RULES procedure, these procedures can add rules to the positive rule set or negative rule set for an apply process. The ADD_SUBSET_RULES procedure can add rules only to the positive rule set for an apply process.

BEGIN
  DBMS_STREAMS_ADM.ADD_TABLE_RULES(
    table_name       => 'hr.departments',
    streams_type     => 'apply',
    streams_name     => 'strm01_apply',
    queue_name       => 'streams_queue',
    include_dml      => true,
    include_ddl      => true,
    source_database  => 'dbs1.net',
    inclusion_rule   => true);
END;
/

BEGIN
  DBMS_STREAMS_ADM.ADD_TABLE_RULES(
    table_name       => 'hr.regions',
    streams_type     => 'apply',
    streams_name     => 'strm01_apply',
    queue_name       => 'streams_queue',
    include_dml      => true,
    include_ddl      => true,
    source_database  => 'dbs1.net',
    inclusion_rule   => false);
END;
/

Removing a Rule from the Rule Set for an Apply Process

You remove a rule from a rule set for an existing apply process by running the REMOVE_RULE procedure in the DBMS_STREAMS_ADM package. For example, the following procedure removes a rule named departments3 from the positive rule set of an apply process named strm01_apply.

BEGIN
  DBMS_STREAMS_ADM.REMOVE_RULE(
    rule_name        => 'departments3',
    streams_type     => 'apply',
    streams_name     => 'strm01_apply',
    drop_unused_rule => true,
    inclusion_rule   => true);
END;
/

In this example, the drop_unused_rule parameter in the REMOVE_RULE procedure is set to true, which is the default setting. Therefore, if the rule being removed is not in any other rule set, then it will be dropped from the database. If the drop_unused_rule parameter is set to false, then the rule is removed from the rule set, but it is not dropped from the database even if it is not in any other rule set.

If the inclusion_rule parameter is set to false, then the REMOVE_RULE procedure removes the rule from the negative rule set for the apply process, not from the positive rule set.

To remove all of the rules in a rule set for the apply process, then specify NULL for the rule_name parameter when you run the REMOVE_RULE procedure.

Removing a Rule Set for an Apply Process

You remove a rule set from an existing apply process using the ALTER_APPLY procedure in the DBMS_APPLY_ADM package. This procedure can remove the positive rule set, negative rule set, or both. Specify true for the remove_rule_set parameter to remove the positive rule set for the apply process. Specify true for the remove_negative_rule_set parameter to remove the negative rule set for the apply process.

For example, the following procedure removes both the positive and negative rule sets from an apply process named strm01_apply.

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name               => 'strm01_apply',
    remove_rule_set          => true,
    remove_negative_rule_set => true);
END;
/

Setting the Message Handler for an Apply Process

Set the message handler for an apply process using the message_handler parameter in the ALTER_APPLY procedure in the DBMS_APPLY_ADM package. For example, the following procedure sets the message handler for an apply process named strm03_apply to the mes_handler procedure in the oe schema.

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name      => 'strm03_apply',
    message_handler => 'oe.mes_handler');
END;
/

The user who runs the ALTER_APPLY procedure must have EXECUTE privilege on the specified message handler.

Removing the Message Handler for an Apply Process

You remove the message handler for an apply process by setting the remove_message_handler parameter to true in the ALTER_APPLY procedure in the DBMS_APPLY_ADM package. For example, the following procedure removes the message handler from an apply process named strm03_apply.

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name             => 'strm03_apply',
    remove_message_handler => true);
END;
/

Creating a Precommit Handler for an Apply Process

A precommit handler must have the following signature:

PROCEDURE handler_procedure (
   parameter_name   IN  NUMBER);

Here, handler_procedure stands for the name of the procedure and parameter_name stands for the name of the parameter passed to the procedure. The parameter passed to the procedure is a commit SCN from an internal commit directive in the queue used by the apply process.

You can use a precommit handler to record information about commits processed by an apply process. The apply process can apply captured messages or user-enqueued messages. For a captured row LCR, a commit directive contains the commit SCN of the transaction from the source database. For a user-enqueued message, the commit SCN is generated by the apply process.

The precommit handler procedure must conform to the following restrictions:

• Any work that commits must be an autonomous transaction.

• Any rollback must be to a named savepoint created in the procedure.

If a precommit handler raises an exception, then the entire apply transaction is rolled back, and all of the messages in the transaction are moved to the error queue.

For example, a precommit handler can be used for auditing the row LCRs applied by an apply process. Such a precommit handler is used with one or more separate DML handlers to record the source database commit SCN for a transaction, and possibly the time when the apply process applies the transaction, in an audit table.

Specifically, this example creates a precommit handler that is used with a DML handler that records information about row LCRs in the following table:

CREATE TABLE strmadmin.history_row_lcrs(
  timestamp             DATE,
  source_database_name  VARCHAR2(128),
  command_type          VARCHAR2(30),
  object_owner          VARCHAR2(32),
  object_name           VARCHAR2(32),
  tag                   RAW(10),
  transaction_id        VARCHAR2(10),
  scn                   NUMBER,
  commit_scn            NUMBER,
  old_values            SYS.LCR$_ROW_LIST,
  new_values            SYS.LCR$_ROW_LIST)
    NESTED TABLE old_values STORE AS old_values_ntab
    NESTED TABLE new_values STORE AS new_values_ntab;

The DML handler inserts a row in the strmadmin.history_row_lcrs table for each row LCR processed by an apply process. The precommit handler created in this example inserts a row into the strmadmin.history_row_lcrs table when a transaction commits.

Create the procedure that inserts the commit information into the history_row_lcrs table:

CREATE OR REPLACE PROCEDURE strmadmin.history_commit(commit_number IN NUMBER)  
 IS
 BEGIN
  -- Insert commit information into the history_row_lcrs table
  INSERT INTO strmadmin.history_row_lcrs (timestamp, commit_scn) 
    VALUES (SYSDATE, commit_number);
END;
/

Setting the Precommit Handler for an Apply Process

A precommit handler processes all commit directives dequeued by an apply process.

Set the precommit handler for an apply process using the precommit_handler parameter in the ALTER_APPLY procedure in the DBMS_APPLY_ADM package. For example, the following procedure sets the precommit handler for an apply process named strm01_apply to the history_commit procedure in the strmadmin schema.

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name        => 'strm01_apply',
    precommit_handler => 'strmadmin.history_commit');
END;
/

You can also specify a precommit handler when you create an apply process using the CREATE_APPLY procedure in the DBMS_APPLY_ADM package.

Removing the Precommit Handler for an Apply Process

You remove the precommit handler for an apply process by setting the remove_precommit_handler parameter to true in the ALTER_APPLY procedure in the DBMS_APPLY_ADM package. For example, the following procedure removes the precommit handler from an apply process named strm01_apply.

BEGIN
  DBMS_APPLY_ADM.ALTER_APPLY(
    apply_name               => 'strm01_apply',
    remove_precommit_handler => true);
END;
/

Setting the Destination Queue for Messages that Satisfy a Rule

You use the SET_ENQUEUE_DESTINATION procedure in the DBMS_APPLY_ADM package to set a destination queue for messages that satisfy a specific rule. For example, to set the destination queue for a rule named employees5 to the queue hr.change_queue, run the following procedure:

BEGIN
  DBMS_APPLY_ADM.SET_ENQUEUE_DESTINATION(
    rule_name               =>  'employees5',
    destination_queue_name  =>  'hr.change_queue');
END;
/

This procedure modifies the action context of the rule to specify the queue. Any apply process in the local database with the employees5 rule in its positive rule set will enqueue a message into hr.change_queue if the message satisfies the employees5 rule. If you want to change the destination queue for the employees5 rule, then run the SET_ENQUEUE_DESTINATION procedure again and specify a different queue.

The apply user of each apply process using the specified rule must have the necessary privileges to enqueue messages into the specified queue. If the queue is a secure queue, then the apply user must be a secure queue user of the queue.

A message that has been enqueued into an queue using the SET_ENQUEUE_DESTINATION procedure is the same as any other user-enqueued message. Such messages can be manually dequeued, applied by an apply process created with the apply_captured parameter set to false, or propagated to another queue.

Removing the Destination Queue Setting for a Rule

You use the SET_ENQUEUE_DESTINATION procedure in the DBMS_APPLY_ADM package to remove a destination queue for messages that satisfy a specified rule. Specifically, you set the destination_queue_name parameter in this procedure to NULL for the rule. When a destination queue specification is removed for a rule, messages that satisfy the rule are no longer enqueued into the queue by an apply process.

For example, to remove the destination queue for a rule named employees5, run the following procedure:

BEGIN
  DBMS_APPLY_ADM.SET_ENQUEUE_DESTINATION(
    rule_name               =>  'employees5',
    destination_queue_name  =>  NULL);
END;
/

Any apply process in the local database with the employees5 rule in its positive rule set no longer enqueues a message into hr.change_queue if the message satisfies the employees5 rule.

Specifying that Messages that Satisfy a Rule Are Not Executed

You use the SET_EXECUTE procedure in the DBMS_APPLY_ADM package to specify that apply processes do not execute messages that satisfy a specified rule. Specifically, you set the execute parameter in this procedure to false for the rule. After setting the execution directive to false for a rule, an apply process with the rule in its positive rule set does not execute a message that satisfies the rule.

For example, to specify that apply processes do not execute messages that satisfy a rule named departments8, run the following procedure:

BEGIN
  DBMS_APPLY_ADM.SET_EXECUTE(
    rule_name   =>  'departments8',
    execute     =>  false);
END;
/

This procedure modifies the action context of the rule to specify the execution directive. Any apply process in the local database with the departments8 rule in its positive rule set will not execute a message if the message satisfies the departments8 rule. That is, if the message is an LCR, then an apply process does not apply the change in the LCR to the relevant database object. Also, an apply process does not send a message that satisfies this rule to any apply handler.

Specifying that Messages that Satisfy a Rule Are Executed

You use the SET_EXECUTE procedure in the DBMS_APPLY_ADM package to specify that apply processes execute messages that satisfy a specified rule. Specifically, you set the execute parameter in this procedure to true for the rule. By default, each apply process executes messages that satisfy a rule in the positive rule set for the apply process, assuming that the message does not satisfy a rule in the negative rule set for the apply process. Therefore, you need to set the execute parameter to true for a rule only if this parameter was set to false for the rule in the past.

For example, to specify that apply processes executes messages that satisfy a rule named departments8, run the following procedure:

BEGIN
  DBMS_APPLY_ADM.SET_EXECUTE(
    rule_name   =>  'departments8',
    execute     =>  true);
END;
/

Any apply process in the local database with the departments8 rule in its positive rule set will execute a message if the message satisfies the departments8 rule. That is, if the message is an LCR, then an apply process applies the change in the LCR to the relevant database object. Also, an apply process sends a message that satisfies this rule to an apply handler if it is configured to do so.

Creating an Error Handler

You create an error handler by running the SET_DML_HANDLER procedure in the DBMS_APPLY_ADM package and setting the error_handler parameter to true.

An error handler must have the following signature:

PROCEDURE user_procedure (
     message             IN ANYDATA,
     error_stack_depth   IN NUMBER,
     error_numbers       IN DBMS_UTILITY.NUMBER_ARRAY,
     error_messages      IN emsg_array);

Here, user_procedure stands for the name of the procedure. Each parameter is required and must have the specified datatype. However, you can change the names of the parameters. The emsg_array parameter must be a user-defined array that is a PL/SQL table of type VARCHAR2 with at least 76 characters.

Running an error handler results in one of the following outcomes:

• The error handler successfully resolves the error, applies the row LCR if appropriate, and returns control back to the apply process.

• The error handler fails to resolve the error, and the error is raised. The raised error causes the transaction to be rolled back and placed in the error queue.

If you want to retry the DML operation, then have the error handler procedure run the EXECUTE member procedure for the LCR.

The following example creates an error handler named regions_pk_error that resolves primary key violations for the hr.regions table. At a destination database, assume users insert rows into the hr.regions table and an apply process applies changes to the hr.regions table that originated from a capture process at a remote source database. In this environment, there is a possibility of errors resulting from users at the destination database inserting a row with the same primary key value as an insert row LCR applied from the source database.

This example creates a table in the strmadmin schema called errorlog to record the following information about each primary key violation error on the hr.regions table:

• The timestamp when the error occurred

• The name of the apply process that raised the error

• The user who caused the error (sender), which is the capture process name for captured messages or the name of the AQ agent for user-enqueued LCRs

• The name of the object on which the DML operation was run, because errors for other objects might be logged in the future

• The type of command used in the DML operation

• The name of the constraint violated

• The error message

• The LCR that caused the error

This error handler resolves only errors that are caused by a primary key violation on the hr.regions table. To resolve this type of error, the error handler modifies the region_id value in the row LCR using a sequence and then executes the row LCR to apply it. If other types of errors occur, then you can use the row LCR you stored in the errorlog table to resolve the error manually.

For example, the following error is resolved by the error handler:

1. At the destination database, a user inserts a row into the hr.regions table with a region_id value of 6 and a region_name value of 'LILLIPUT'.

2. At the source database, a user inserts a row into the hr.regions table with a region_id value of 6 and a region_name value of 'BROBDINGNAG'.

3. A capture process at the source database captures the change described in Step 2.

4. A propagation propagates the LCR containing the change from a queue at the source database to the queue used by the apply process at the destination database.

5. When the apply process tries to apply the LCR, an error results because of a primary key violation.

6. The apply process invokes the error handler to handle the error.

7. The error handler logs the error in the strmadmin.errorlog table.

8. The error handler modifies the region_id value in the LCR using a sequence and executes the LCR to apply it.

Complete the following steps to create the regions_pk_error error handler:

1. Create the sequence used by the error handler to assign new primary key values by connecting as hr user and running the following statement:

   CONNECT hr/hr
   
   CREATE SEQUENCE hr.reg_exception_s START WITH 9000;
   
   

   This example assumes that users at the destination database will never insert a row into the hr.regions table with a region_id greater than 8999.

2. Grant the Streams administrator ALL privilege on the sequence:

   GRANT ALL ON reg_exception_s TO strmadmin;
   
   

3. Create the errorlog table by connecting as the Streams administrator and running the following statement:

   CONNECT strmadmin/strmadminpw
   
   CREATE TABLE strmadmin.errorlog(
     logdate       DATE,
     apply_name    VARCHAR2(30),
     sender        VARCHAR2(100),
     object_name   VARCHAR2(32),
     command_type  VARCHAR2(30),
     errnum        NUMBER,
     errmsg        VARCHAR2(2000),
     text          VARCHAR2(2000),
     lcr           SYS.LCR$_ROW_RECORD);
   
   

4. Create a package that includes the regions_pk_error procedure:

   CREATE OR REPLACE PACKAGE errors_pkg 
   AS
    TYPE emsg_array IS TABLE OF VARCHAR2(2000) INDEX BY BINARY_INTEGER;
    PROCEDURE regions_pk_error( 
      message            IN ANYDATA,
      error_stack_depth  IN NUMBER,
      error_numbers      IN DBMS_UTILITY.NUMBER_ARRAY,
      error_messages     IN EMSG_ARRAY);
   END errors_pkg ;
   /
   
   

5. Create the package body:

   CREATE OR REPLACE PACKAGE BODY errors_pkg AS
    PROCEDURE regions_pk_error ( 
      message            IN ANYDATA,
      error_stack_depth  IN NUMBER,
      error_numbers      IN DBMS_UTILITY.NUMBER_ARRAY,
      error_messages     IN EMSG_ARRAY )
    IS
     reg_id     NUMBER;
     ad         ANYDATA;
     lcr        SYS.LCR$_ROW_RECORD;
     ret        PLS_INTEGER;
     vc         VARCHAR2(30);
     apply_name VARCHAR2(30);
     errlog_rec errorlog%ROWTYPE ;
     ov2        SYS.LCR$_ROW_LIST;
    BEGIN
     -- Access the error number from the top of the stack.
     -- In case of check constraint violation,
     -- get the name of the constraint violated.
     IF error_numbers(1) IN ( 1 , 2290 ) THEN
      ad  := DBMS_STREAMS.GET_INFORMATION('CONSTRAINT_NAME');
      ret := ad.GetVarchar2(errlog_rec.text);
     ELSE 
      errlog_rec.text := NULL ;
     END IF ;
     -- Get the name of the sender and the name of the apply process.
     ad  := DBMS_STREAMS.GET_INFORMATION('SENDER');
     ret := ad.GETVARCHAR2(errlog_rec.sender);
     apply_name := DBMS_STREAMS.GET_STREAMS_NAME();
     -- Try to access the LCR.
     ret := message.GETOBJECT(lcr);
     errlog_rec.object_name  := lcr.GET_OBJECT_NAME() ;
     errlog_rec.command_type := lcr.GET_COMMAND_TYPE() ;
     errlog_rec.errnum := error_numbers(1) ;
     errlog_rec.errmsg := error_messages(1) ;
     INSERT INTO strmadmin.errorlog VALUES (SYSDATE, apply_name, 
          errlog_rec.sender, errlog_rec.object_name, errlog_rec.command_type, 
          errlog_rec.errnum, errlog_rec.errmsg, errlog_rec.text, lcr);
     -- Add the logic to change the contents of LCR with correct values.
     -- In this example, get a new region_id number 
     -- from the hr.reg_exception_s sequence.
     ov2 := lcr.GET_VALUES('new', 'n');
     FOR i IN 1 .. ov2.count
     LOOP
       IF ov2(i).column_name = 'REGION_ID' THEN
        SELECT hr.reg_exception_s.NEXTVAL INTO reg_id FROM DUAL; 
        ov2(i).data := ANYDATA.ConvertNumber(reg_id) ;
       END IF ;
     END LOOP ;
     -- Set the NEW values in the LCR.
     lcr.SET_VALUES(value_type => 'NEW', value_list => ov2);
     -- Execute the modified LCR to apply it.
     lcr.EXECUTE(true);
    END regions_pk_error;
   END errors_pkg;
   /
   
   

   Note:

   • For subsequent changes to the modified row to be applied successfully, you should converge the rows at the two databases as quickly as possible. That is, you should make the region_id for the row match at the source and destination database. If you do not want these manual changes to be recaptured at a database, then use the SET_TAG procedure in the DBMS_STREAMS package to set the tag for the session in which you make the change to a value that is not captured.

   • This example error handler illustrates the use of the GET_VALUES member function and SET_VALUES member procedure for the LCR. If you are modifying only one value in the LCR, then the GET_VALUE member function and SET_VALUE member procedure might be more convenient and more efficient.

   See Also:

   Oracle Streams Replication Administrator's Guide for more information about setting tag values generated by the current session

Setting an Error Handler

An error handler handles errors resulting from a row LCR dequeued by any apply process that contains a specific operation on a specific table. You can specify multiple error handlers on the same table, to handle errors resulting from different operations on the table. You can either set an error handler for a specific apply process, or you can set an error handler as a general error handler that is used by all apply processes that apply the specified operation to the specified table.

Set an error handler using the SET_DML_HANDLER procedure in the DBMS_APPLY_ADM package. When you run this procedure to set an error handler, set the error_handler parameter to true.

For example, the following procedure sets the error handler for INSERT operations on the hr.regions table. Therefore, when any apply process dequeues a row LCR containing an INSERT operation on the local hr.regions table, and the row LCR results in an error, the apply process sends the row LCR to the strmadmin.errors_pkg.regions_pk_error PL/SQL procedure for processing. If the error handler cannot resolve the error, then the row LCR and all of the other row LCRs in the same transaction are moved to the error queue.

In this example, the apply_name parameter is set to NULL. Therefore, the error handler is a general error handler that is used by all of the apply processes in the database.

Run the following procedure to set the error handler:

BEGIN
  DBMS_APPLY_ADM.SET_DML_HANDLER(
    object_name         => 'hr.regions',
    object_type         => 'TABLE',
    operation_name      => 'INSERT',
    error_handler       => true,
    user_procedure      => 'strmadmin.errors_pkg.regions_pk_error',
    apply_database_link => NULL,
    apply_name          => NULL);
END;
/

Unsetting an Error Handler

You unset an error handler using the SET_DML_HANDLER procedure in the DBMS_APPLY_ADM package. When you run that procedure, set the user_procedure parameter to NULL for a specific operation on a specific table.

For example, the following procedure unsets the error handler for INSERT operations on the hr.regions table:

BEGIN
  DBMS_APPLY_ADM.SET_DML_HANDLER(
    object_name    => 'hr.regions',
    object_type    => 'TABLE',
    operation_name => 'INSERT',
    user_procedure => NULL,
    apply_name     => NULL);
END;
/

Retrying Apply Error Transactions

You can retry a specific error transaction or you can retry all error transactions for an apply process. You might need to make DML or DDL changes to database objects to correct the conditions that caused one or more apply errors before you retry error transactions. You can also have one or more capture processes configured to capture changes to the same database objects, but you might not want the changes captured. In this case, you can set the session tag to a value that will not be captured for the session that makes the changes.

BEGIN
  DBMS_APPLY_ADM.EXECUTE_ERROR(
    local_transaction_id => '5.4.312',
    execute_as_user      => false,
    user_procedure       => NULL);
END;
/

CREATE OR REPLACE PROCEDURE strmadmin.modify_emp_salary(
  in_any                        IN      ANYDATA,
  error_record                  IN      DBA_APPLY_ERROR%ROWTYPE,
  error_message_number          IN      NUMBER,
  messaging_default_processing  IN OUT  BOOLEAN,
  out_any                       OUT     ANYDATA)
AS
  row_lcr          SYS.LCR$_ROW_RECORD;
  row_lcr_changed  BOOLEAN := FALSE;
  res              NUMBER;
  ob_owner         VARCHAR2(32);
  ob_name          VARCHAR2(32);
  cmd_type         VARCHAR2(30);
  employee_id      NUMBER;
BEGIN
  IF in_any.getTypeName() = 'SYS.LCR$_ROW_RECORD' THEN
    -- Access the LCR
    res := in_any.GETOBJECT(row_lcr);
    -- Determine the owner of the database object for the LCR
    ob_owner := row_lcr.GET_OBJECT_OWNER;
    -- Determine the name of the database object for the LCR
    ob_name := row_lcr.GET_OBJECT_NAME;
    -- Determine the type of DML change
    cmd_type := row_lcr.GET_COMMAND_TYPE;
    IF (ob_owner = 'HR' AND ob_name = 'EMPLOYEES' AND cmd_type = 'UPDATE') THEN
      -- Determine the employee_id of the row change
      IF row_lcr.GET_VALUE('old', 'employee_id') IS NOT NULL THEN
        employee_id := row_lcr.GET_VALUE('old', 'employee_id').ACCESSNUMBER();
        IF (employee_id = 197) THEN
          -- error_record.message_number should equal error_message_number
          row_lcr.SET_VALUE(
          value_type => 'OLD',
          column_name => 'salary',
          column_value => ANYDATA.ConvertNumber(3250));
          row_lcr_changed := TRUE;
        END IF;
      END IF;
    END IF;
  END IF;
  -- Specify that the apply process continues to process the current message
  messaging_default_processing := TRUE;
  -- assign out_any appropriately
  IF row_lcr_changed THEN
    out_any := ANYDATA.ConvertObject(row_lcr);
  ELSE
    out_any := in_any;
  END IF;
END;
/

BEGIN
  DBMS_APPLY_ADM.EXECUTE_ERROR(
    local_transaction_id => '5.6.924',
    execute_as_user      => false,
    user_procedure       => 'strmadmin.modify_emp_salary');
END;
/

BEGIN
  DBMS_APPLY_ADM.EXECUTE_ALL_ERRORS(
    apply_name       => 'strm01_apply',
    execute_as_user  => false);
END;
/

Deleting Apply Error Transactions

You can delete a specific error transaction or you can delete all error transactions for an apply process.

EXEC DBMS_APPLY_ADM.DELETE_ERROR(local_transaction_id => '5.4.312');

EXEC DBMS_APPLY_ADM.DELETE_ALL_ERRORS(apply_name => 'strm01_apply');