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Oracle® Database PL/SQL Packages and Types Reference
11g Release 2 (11.2)

Part Number E16760-04
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34 DBMS_CDC_SUBSCRIBE

Note:

Oracle Change Data Capture will be de-supported in a future release of Oracle Database and will be replaced with Oracle GoldenGate. Therefore, Oracle strongly recommends that you use Oracle GoldenGate for new applications.

For Oracle Database 11g Release 2 (11.2), Change Data Capture continues to function as in earlier releases. If you are currently using Change Data Capture, then you will be able to continue to do so for the foreseeable future. However, Change Data Capture will not be further enhanced, and will only be supported based on the current, documented functionality.

The DBMS_CDC_SUBSCRIBE package, one of a set of Change Data Capture packages, lets subscribers view and query change data that was captured and published with the DBMS_CDC_PUBLISH package.

A Change Data Capture system usually has one publisher and many subscribers. The subscribers (applications or individuals), use the Oracle supplied package, DBMS_CDC_SUBSCRIBE, to access published data.

See Also:

Oracle Database Data Warehousing Guide for information regarding Oracle Change Data Capture.

This chapter contains the following topics:


Using DBMS_CDC_SUBSCRIBE

This section contains the following topics, which relate to using the DBMS_CDC_SUBSCRIBE package:


Overview

The primary role of the subscriber is to use the change data. Through the DBMS_CDC_SUBSCRIBE package, each subscriber registers interest in source tables by subscribing to them.

Once the publisher sets up the system to capture data into change tables (which are viewed as publications by subscribers) and grants subscribers access to the change tables, subscribers can access and query the published change data for any of the source tables of interest. Using the subprograms in the DBMS_CDC_SUBSCRIBE package, the subscriber accomplishes the following main objectives:

  1. Indicates the change data of interest by creating a subscription and associated subscriber views on published source tables and source columns

  2. Activates the subscription to indicate that the subscriber is ready to receive change data

  3. Extends the subscription window to receive a new set of change data

  4. Uses SQL SELECT statements to retrieve change data from the subscriber views

  5. Purges the subscription window when finished processing a block of changes

  6. Drops the subscription when finished with the subscription

Figure 34-1 provides a graphical flowchart of the order in which subscribers most typically use the subprograms in the DBMS_CDC_SUBSCRIBE package (which are listed in Table 34-1). A subscriber would typically create a subscription, subscribe to one or more source tables and columns, activate the subscription, extend the subscription window, query the subscriber views, purge the subscription window, and then either extend the subscription window again or drop the subscription.

Note:

If a subscriber uses the PURGE_WINDOW procedure immediately after using an EXTEND_WINDOW procedure, then change data may be lost without ever being processed.

See Also:

Chapter 34, "DBMS_CDC_SUBSCRIBE" for information on the package for publishing change data.

Figure 34-1 Subscription Flow

Description of Figure 34-1 follows
Description of "Figure 34-1 Subscription Flow "


Deprecated Subprograms

The following subprograms are deprecated with Oracle Database 11g:


Security Model

Change Data Capture grants EXECUTE privileges to PUBLIC on the DBMS_CDC_SUBSCRIBE package.


Views

The DBMS_CDC_SUBSCRIBE package uses the views listed in the section on Getting Information About the Change Data Capture Environment in Oracle Database Data Warehousing Guide.


Summary of DBMS_CDC_SUBSCRIBE Subprograms

Table 34-1 DBMS_CDC_SUBSCRIBE Package Subprograms

Subprogram Description

ACTIVATE_SUBSCRIPTION Procedure

Indicates that a subscription is ready to start accessing change data

CREATE_SUBSCRIPTION Procedure

Creates a subscription and associates it with one change set

DROP_SUBSCRIPTION Procedure

Drops a subscription that was created with a prior call to the CREATE_SUBSCRIPTION procedure

EXTEND_WINDOW Procedure

Sets a subscription window high boundary so that new change data can be seen

PURGE_WINDOW Procedure

Sets the low boundary for a subscription window to notify Change Data Capture that the subscriber is finished processing a set of change data

SUBSCRIBE Procedure

Specifies a source table and the source columns for which the subscriber wants to access change data and specifies the subscriber view through which the subscriber sees change data for the source table



ACTIVATE_SUBSCRIPTION Procedure

This procedure indicates that a subscription is ready to start accessing change data.

Syntax

DBMS_CDC_SUBSCRIBE.ACTIVATE_SUBSCRIPTION (
     subscription_name  IN VARCHAR2);

Parameters

Table 34-2 ACTIVATE_SUBSCRIPTION Procedure Parameters

Parameter Description

subscription_name

The name of the subscription that was specified for a previous call to the CREATE_SUBSCRIPTION procedure. Subscription names follow the Oracle schema object naming rules.


Exceptions

Table 34-3 ACTIVATE_SUBSCRIPTION Procedure Exceptions

Exception Description

ORA-31409

One or more values for input parameters are incorrect

ORA-31425

Subscription does not exist

ORA-31426

Cannot modify active subscriptions

ORA-31469

Cannot enable Change Data Capture for change set

ORA-31514

Change set disabled due to capture error


Usage Notes


CREATE_SUBSCRIPTION Procedure

This procedure creates a subscription that is associated with one change set. This procedure replaces the deprecated GET_SUBSCRIPTION_HANDLE procedure.

Syntax

DBMS_CDC_SUBSCRIBE.CREATE_SUBSCRIPTION (
     change_set_name      IN  VARCHAR2,
     description          IN  VARCHAR2,
     subscription_name    IN  VARCHAR2);

Parameters

Table 34-4 CREATE_SUBSCRIPTION Procedure Parameters

Parameter Description

change_set_name

The name of an existing change set to which the subscriber subscribes

description

A description of the subscription (which might include, for example, the purpose for which it is used). The description must be specified using 255 or fewer characters.

subscription_name

A unique name for a subscription that must consist of 30 characters or fewer and cannot have a prefix of CDC$. Subscription names follow the Oracle schema object naming rules.


Exceptions

Table 34-5 CREATE_SUBSCRIPTION Procedure Exceptions

Exception Description

ORA-31409

One or more values for input parameters are incorrect

ORA-31415

Specified change set does not exist

ORA-31449

Invalid value for change_set_name

ORA-31457

Maximum length of description field exceeded

ORA-31469

Cannot enable Change Data Capture for change set

ORA-31506

Duplicate subscription name specified

ORA-31510

Name uses reserved prefix CDC$

ORA-31511

Name exceeds maximum length of 30 characters


Usage Notes


DROP_SUBSCRIPTION Procedure

This procedure drops a subscription.

Syntax

DBMS_CDC_SUBSCRIBE.DROP_SUBSCRIPTION (
     subscription_name  IN VARCHAR2);

Parameters

Table 34-6 DROP_SUBSCRIPTION Procedure Parameters

Parameter Description

subscription_name

The name of the subscription that was specified for a previous call to the CREATE_SUBSCRIPTION procedure. Subscription names follow the Oracle schema object naming rules.


Exceptions

Table 34-7 DROP_SUBSCRIPTION Procedure Exceptions

Exception Description

ORA-31409

One or more values for input parameters are incorrect

ORA-31425

Subscription does not exist


Usage Notes

Subscribers should be diligent about dropping subscriptions that are no longer needed so that change data will not be held in the change tables unnecessarily.


EXTEND_WINDOW Procedure

This procedure sets the subscription window high boundary so that new change data can be seen.

Syntax

DBMS_CDC_SUBSCRIBE.EXTEND_WINDOW (
     subscription_name  IN VARCHAR2,
     upper_bound        IN DATE DEFAULT NULL);

Parameters

Table 34-8 EXTEND_WINDOW Procedure Parameters

Parameter Description

subscription_name

The unique name of the subscription that was specified by a previous call to the CREATE_SUBSCRIPTION procedure. Subscription names follow the Oracle schema object naming rules.

upper_bound

A date/timestamp to move the upper bound of the subscription window to.


Exceptions

Table 34-9 EXTEND_WINDOW Procedure Exceptions

Exception Description

ORA-31409

One or more values for input parameters are incorrect

ORA-31425

Subscription does not exist

ORA-31429

Subscription has not been activated

ORA-31432

Invalid source table

ORA-31469

Cannot enable Change Data Capture for change set

ORA-31508

Invalid parameter value for synchronous change set

ORA-31509

Publication does not exist

ORA-31514

Change set disabled due to capture error


Usage Notes


PURGE_WINDOW Procedure

This procedure sets the low boundary of the subscription window so that the subscription no longer sees any change data, effectively making the subscription window empty. The subscriber calls this procedure to notify Change Data Capture that the subscriber is finished processing a block of change data.

Syntax

DBMS_CDC_SUBSCRIBE.PURGE_WINDOW (
     subscription_name   IN VARCHAR2,
     lower_bound         IN DATE DEFAULT NULL);

Parameters

Table 34-10 PURGE_WINDOW Procedure Parameters

Parameter Description

subscription_name

The name of the subscription that was specified for a previous call to the CREATE_SUBSCRIPTION procedure. Subscription names follow the Oracle schema object naming rules.

lower_bound

A date/timestamp to move the lower bound of the subscription window to.


Exceptions

Table 34-11 PURGE_WINDOW Procedure Exceptions

Exception Description

ORA-31409

One or more values for input parameters are incorrect

ORA-31425

Subscription does not exist

ORA-31429

Subscription has not been activated

ORA-31432

Invalid source table

ORA-31469

Cannot enable Change Data Capture for change set

ORA-31514

Change set disabled due to capture error


Usage Notes


SUBSCRIBE Procedure

This procedure specifies a source table and the source columns for which the subscriber wants to access change data. In addition, it specifies the subscriber view through which the subscriber sees change data for the source table.

Syntax

There are two versions of syntax for the SUBSCRIBE procedure, as follow:

Parameters

Table 34-12 SUBSCRIBE Procedure Parameters

Parameter Description

subscription_name

The name of a subscription that was specified for, or returned by, a previous call to the CREATE_SUBSCRIPTION procedure. Subscription names follow the Oracle schema object naming rules.

source_schema

The name of the schema where the source table resides

source_table

The name of a published source table

column_list

A comma-delimited list of columns from the published source table or publication

subscriber_view

Unique name for the subscriber view for this source table or publication that must consist of 30 or fewer characters and must not have a prefix of CDC$. Subscriber view names follow the Oracle schema object naming rules.

publication_id

A valid publication_id, which the subscriber can obtain from the ALL_PUBLISHED_COLUMNS view.


Exceptions

Table 34-13 SUBSCRIBE Procedure Exceptions

Exception Description

ORA-31409

One or more values for input parameters are incorrect

ORA-31425

Subscription does not exist

ORA-31426

Cannot modify active subscriptions

ORA-31427

Publication string already subscribed

ORA-31428

No publication contains all the specified columns

ORA-31432

Invalid source table

ORA-31466

No publications found

ORA-31469

Cannot enable Change Data Capture for change set

ORA-31510

Name uses reserved prefix CDC$

ORA-31511

Name exceeds maximum length of 30 characters


Usage Notes