Check Details
Check objective
Verify whether the column set of existing CDC capture instances in the source database is consistent with the current columns of the source table, preventing task failures during the incremental phase due to column definition mismatches and surfacing issues before task startup rather than during the incremental phase.
Check content
DTS adds a CDC column consistency check before task startup to detect whether the column set of CDC capture instances in the source database is consistent with the current columns of the source table.
Note:
The column set of a capture instance is fixed at creation and is not automatically updated with source table DDL changes. Typical scenario: A capture instance is created first, and then an ALTER TABLE ADD COLUMN command is executed on the source table.
Potential issue
If the column set of a CDC capture instance on the source table is inconsistent with the current columns of the source table, the first capture cycle in the incremental phase will report "Invalid column name" and cause the task to fail.
Fixing Method
Rebuild the capture instance: If a mismatch is detected, rebuild the CDC capture instance for the table in the source database as prompted.
Use sys.sp_cdc_disable_table to disable the old capture instance.
Use sys.sp_cdc_enable_table to create a new capture instance.
Perform the operation during off-peak hours to avoid impacting the source database business.
Query failure degradation: If a check query fails due to insufficient permissions or other reasons, the failure is downgraded to an alarm instead of blocking the task. Pay attention to the alarm, supplement the required permissions, and then re-validate.