Microsoft SQL Server CDC Connector

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Configuring a restart point for change data extraction

When you create or edit a mapping task, you can specify a restart point. The restart point indicates the point in the PowerExchange Logger log files from which the PWX CDC Reader starts extracting change records that were captured from a CDC source table. By default, the restart point is the end of log for the first run. Thereafter, the mapping task restarts from where it last left off by default, unless you specify a restart point.

Usually, you set the restart point before you start the mapping task the first time to coincide with the time at which the mapped target was materialized with data. However, you might need to set the restart point at other times, such as when you need to reprocess change records or perform tests.

The restart point applies to all source tables in the mapping that is associated with the mapping task.

The first time you run the mapping task, Data Integration detects that the task has not been run previously and performs an implicit cold start, honoring the restart point.

On the

CDC Runtime

page, click

Select

next to the

Restart Point

property.

The

Select Restart Point

dialog box appears.

To set a restart point, select one of the following options:

End of log

. The latest change record in the Logger logs.

Earliest available

. The oldest available change record in the Logger logs.

Timestamp

. The logged change record associated with a timestamp you set. To set a timestamp, select a date from the date picker. Then enter the time in HH:MM:SS.s format in the adjacent list boxes, where s represents fractional seconds.

PWX Token

. The PowerExchange restart token that was automatically generated during change data capture. To obtain the restart token, use one of the following methods:

Run a CAPX row test on the extraction map in PowerExchange Navigator. In the row test results window, select

Show Auto Generated Columns

to see the generated DTL__ columns. Take the value from the DTL__CAPXRESTART1 field and add eight zeroes at the end. Enter the edited value in the

PWX Token

field. For more information about running a CAPX row test, see the

PowerExchange Navigator User Guide

Run the PWXUCDCT utility with the REPORT_CDCT command. The report output shows the restart token for each PowerExchange Logger log file. For more information about the PWXUCDCT utility, see the

PowerExchange Utilities Guide.

Click

On the

CDC Runtime

page, the

Restart Point

property displays the new restart point in read-only mode and the

Restart Revision

value is incremented by 1.

Data Integration performs an implicit cold start when the revision number is incremented through the

Select Restart Point

dialog box that appears when you click

Select

for the

Restart Point

on the

CDC Runtime

page of the mapping task. The revision number is incremented even if you did not change the option. In this case, the mapping task does not start from the end of log position of the previous run and might read duplicate records or skip records. Ensure that this result is acceptable.

Mapping task configuration

Recovery and restart processing

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