Informatica Power Exchange Change Data Capture Implementation For Oracle

  • Power Exchange Listener : The PowerExchange Listener manages data maps for non relational files and capture registrations and extraction maps for all data sources. It also handles extraction requests for bulk data and change data.  
             1) CCT file for capture registrations
             2) CAMAPS directory for extraction maps
             3) DATAMAPS directory for DB2 data maps

  • Power Exchange Logger: PowerExchange Logger receives captured change data from the ECCRs that are connected to it and stores the change data in log data sets. 

The PowerExchange Logger for Linux, UNIX, and Windows captures change data from DB2 recovery logs, Oracle redo logs, or a SQL Server distribution database and writes that data to PowerExchange Logger log files.

Use of the PowerExchange Logger is optional. To use the PowerExchange Logger, run one PowerExchange Logger process for each database type and instance. The PowerExchange Logger writes all successful UOWs in chronological order based on end time to its log files. This practice maintains transactional integrity. You can extract the change data from the PowerExchange Logger log files in either batch or continuous mode. 

Source database overhead is reduced because PowerExchange makes fewer accesses to the source log files or database to read change data. For Oracle, this overhead reduction can be significant

The PowerExchange Logger can use only one Oracle Log Miner session to read change data for all extractions that process an Oracle instance.

You do not need to retain the source RDBMS log files longer than normal for CDC.

PowerExchange does not need to reposition its point in the DB2 or Oracle logs from which to resume reading data. This feature can significantly reduce restart times.
  •  Power Exchange Condenser : Condense creates condense files that contain a condensed version of the changes that were captured by an ECCR and stored by the Power Exchange Logger.

  • The Power Exchange Navigator : Is the graphical user interface that you use to define and manage data maps, capture registrations, and extraction maps for the data sources from which you want to extract bulk data or capture change data.

You must define a capture registration for each source table. The corresponding extraction map is automatically generated. For DB2 sources, you can also define data maps if you need to perform column-level processing, such as adding user-defined columns and building expressions to populate them.


You can import the extraction maps into PowerCenter so that they can be used for
            moving change data to the target
         
Features of  Change Data Capture :

PowerExchange Change Data Capture (CDC) works in conjunction with PowerCenter to capture changes to data in source tables and replicate those changes to target tables and files.

Relational Sources Which It Supports :

1) DB2 for Linux, UNIX, and Windows
2) Microsoft SQL Server on Windows
3) Oracle on Linux, UNIX, or Windows

After materializing target tables or files with PowerExchange bulk data movement, you can use PowerExchange CDC to synchronize the targets with their corresponding source tables. Synchronization is faster when you replicate only the change data rather than all of the data.

Steps Involved in Change Data Replication :  

Change Data Capture: PowerExchange captures change data for the source tables. PowerExchange can read change data directly from the RDBMS log files or database. Optionally, you can use the PowerExchange Logger for Linux, UNIX, and Windows to capture change data to its log files.

Change Data Extraction: PowerExchange, in conjunction with PowerCenter, extracts captured change data for movement to the target.

Change data apply: PowerExchange, in conjunction with PowerCenter, transforms and applies the extracted change data to target tables or files.

Integrate Power Exchange With Power center :

  • PowerCenter works in conjunction with the PowerExchange Client for PowerCenter (PWXPC) to extract the change data that PowerExchange captured and apply it to one or more targets.

  • The primary function of PWXPC is to integrate PowerExchange with PowerCenter so that PowerCenter can access PowerExchange-controlled data and write it to various targets. With PWXPC, CDC sessions can extract change data directly from the change stream and from PowerExchange Logger for Linux, UNIX, and Windows log files.  

  • PowerCenter provides transformation and data cleansing capabilities, which you can use in your CDC sessions. 
   Power Exchange Change Data Capture Architecture :



  Change Data Capture Implementation :

  1. Configure parameters in the dbmover.cfg file for the PowerExchange Listener.
  2. Start the PowerExchange Listener on the machine with the source database.
  3. Perform RDBMS-specific configuration tasks for CDC.
  4. Configure the PowerExchange Logger.
  5. Start the PowerExchange Logger.
   Define Data Sources For CDC :
  • From the PowerExchange Navigator, define and activate capture registrations and extraction maps for the data sources.
  • For DB2 sources that have user-defined or multi-field columns that you want to manipulate, create DB2 data maps.

Materialize targets and start capturing changes:
  1. Materialize the target from the source.
  2. Establish a start point for the extraction

Extract and apply change data :

  From PowerCenter, configure mappings, workflows, connections, and sessions. Then run the  workflow.

 

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