CDC Guide for Linux, UNIX, and Windows

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Explicit Override Statements

Use explicit override statements to specify a restart token pair for a specific source.

You can specify explicit override statements for one or more sources in a CDC session. Also, you can use explicit override statements in conjunction with special override statements to provide restart tokens for all sources in a CDC session.

When you warm start a CDC session, the explicit override statements for a source override the restart tokens in the state table or state file for that source.

When defining explicit override statements for a source, specify a pair of statements, each containing an extraction map name and a restart or sequence token value. Because a source can have multiple extraction maps with distinct names, you might have multiple pairs of explicit override statements for a source.

Explicit override statements use the following parameters:

extraction_map_name={restart1_token|CURRENT_RESTART}
extraction_map_name={restart2_token|CURRENT_RESTART}

Review the following parameter descriptions:

extraction_ map_name: The name of an extraction map for the data source. To determine the extraction map name, use one of the following methods:

For CDC data map sources, see the
Schema Name Override
and
Map Name Override
attributes in the session properties. These attributes override the schema name and map name in the source extraction map. Or, in Designer, see the
Schema Name
and
Map Name
values in the source Metadata Extensions.

For relational sources, see the
Extraction Map Name
attribute in the session properties.
restart1_token: The sequence token portion of a restart token pair. This value varies based on data source type.
restart2_token: The restart token portion of a restart token pair. This value based on data source type.
CURRENT_RESTART: PowerExchange generates restart tokens for the current end of the change stream. The PWXPC CDC reader opens a separate connection to PowerExchange, requests the generation of current restart tokens, and then provides the token values to all applicable sources.

You can generate current restart tokens in the
Database Row Test
dialog box of the PowerExchange Navigator.

Use CURRENT_RESTART only for CDC sessions that use real-time extraction mode or continuous extraction mode.

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CDC Guide for Linux, UNIX, and Windows

CDC Guide for Linux, UNIX, and Windows

Explicit Override Statements

Explicit Override Statements