CDC Guide for Linux, UNIX, and Windows

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Remote Logging of Data from Linux, UNIX, or Windows Sources

You can use the PowerExchange Logger for Linux, UNIX, and Windows to extract change data from sources on a Linux, UNIX, or Windows system and log that data to another Linux, UNIX, or Windows system. PowerCenter CDC sessions can then extract the change data from the log files on the PowerExchange Logger system.

For Linux, UNIX, and Windows sources, the remote logging of data has the advantage of maximizing the performance of the capture process while minimizing the impact on the database server. Remote logging has the following benefits:

Reduces disk space and CPU usage on the source database server by moving PowerExchange Logger processing and log files to another Linux, UNIX, or Windows system.

Retains local access to the source database and database logs, which eliminates the latency of accessing the source across a network and avoids having to configure NFS to export the database logs.

Retains object filtering and any internal UOW cleansing processing on the source system. Only the data of interest is sent across the network.

Allows multiple PowerCenter sessions to access the same logged data without increasing overhead on the database server and, if the PowerExchange Logger runs on the same server as PowerCenter, without affecting network latency.

To configure this remote logging scenario, you must specify the CAPTURE_NODE statement in the PowerExchange Logger for Linux, UNIX , and Windows configuration file, pwxccl.cfg, on the system where the Logger runs. The CAPTURE_NODE statement specifies the node name of the PowerExchange Listener that runs on the source system. When you create the registration group in the PowerExchange Navigator, enter the node name of the PowerExchange Listener that runs on the source system in the

Location

field. In PowerCenter, configure a PWX CDC Real Time connection for the PowerCenter CDC sessions that process change data from the source. In the connection attributes, set the

Location

attribute to the node name of the PowerExchange Listener that runs on the system where the PowerExchange Logger log files reside, and set the

Mapping Location

attribute to the node name of the PowerExchange Listener that runs on the source system where the extraction maps reside.

When the PowerExchange Logger for Linux, UNIX, and Windows runs on the PowerCenter ISP machine, you can use a Local connection rather than run a PowerExchange Listener on this machine. However, Informatica recommends that you run a PowerExchange Listener on the PowerCenter ISP machine so that you can issue commands to display information about the active PowerExchange Listener tasks, print PowerExchange Listener monitoring statistics, and stop the PowerExchange Listener task, if necessary.

For example, configure the PowerExchange Logger for Linux, UNIX, and Windows to extract Db2 change data from Db2 database logs on a Linux system and then log that data to PowerExchange Logger log files on the PowerCenter ISP system. The following image shows this type of configuration:

In this scenario, set the PowerExchange Logger CAPTURE_NODE statement to the node name of the PowerExchange Listener on the Db2 source system. Set the PowerCenter

Location

connection attribute to the node name of the PowerExchange Listener on the PowerCenter ISP machine where the PowerExchange Logger runs. Set the

Map Location

connection attribute to the node name of the PowerExchange Listener on the Db2 source system.

When the PowerExchange Logger sends a change data capture request, the PowerExchange Listener on the source system communicates with the CAPI to retrieve change data from the Db2 database logs by means of the Db2 LogRead API. The PowerExchange Listener sends only the committed UOWs for the objects of CDC interest to the PowerExchange Logger on the remote system. The PowerExchange Logger logs the data in its log files. When a PowerCenter CDC session requests change data for the tables of CDC interest, the PowerExchange Client for PowerCenter (PWXPC) communicates with the PowerExchange Listener on the PowerExchange Logger system to get the change data from the local PowerExchange Logger log files.

Remote Logging Overview

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