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SQL Development
Change Data Capture : Using SQL to query CDC data

Using SQL to query CDC data

This section describes how applications can build queries to access CDC data in order for the application to use the CDC data and perform tasks like ETL. The following table contains information on basic CDC schema and related tables:
Table 7. ABL and OpenEdge SQL data types
CDC/Schema table name
CDC table Policy
Defines a database table for CDC and declares which changes the OpenEdge database will capture.
CDC Field Policy
Defines specific fields for which changes should be captured. CDC Field Policy is optional.
_File table
This is a basic schema table for table definitions
source table
This is the application table for which changes are tracked by CDC
Note: The source table need not be a CDC table
CDC Change Tracking table
This refers to many individual Change tables implicitly, using references to the table Policy, and the table Policy’s source table, for individual changes
CDC Change table
A specific table containing change data as prescribed by CDC table Policy for a given source table.
*The Change table exists only for a Policy at tracking Level 2 or Level 3
*All table Policies for a given source table use a single Change table, which contains changes for the given source table only
*A Change table has a well-known, default name – the source table name prefixed by “CDC_” and a table pub.customer would have a Change table pub.CDC_customer
*It is possible to have a custom Change table name, defined by the DBA creating the CDC table Policy for the source table.
*The name of any Change table is contained in its corresponding table Policy definition row.