Returns the maximum log sequence number (LSN) from the start_lsn column in the cdc.lsn_time_mapping system table. You can use this function to return the high endpoint of the change data capture timeline for any capture instance.
This function returns the maximum LSN in the start_lsn column of the cdc.lsn_time_mapping table. As such, it is the last LSN processed by the capture process when changes are propagated to the database change tables. It serves as the high endpoint for the all timelines that are associated with capture instances defined for the database. For more information about the change data capture timeline, see Configuring Change Data Capture.
The function is typically used to obtain an appropriate high endpoint for a query interval.
A. Returning the maximum LSN value
The following example returns the maximum LSN for all capture instances in the AdventureWorks database.
USE AdventureWorks; GO SELECT sys.fn_cdc_get_max_lsn()AS max_lsn;
B. Setting the high endpoint of a query range
The following example uses the maximum LSN returned by sys.fn_cdc_get_max_lsn to set the high endpoint for a query range for the capture instance HumanResources_Employee.
USE AdventureWorks; GO DECLARE @from_lsn binary(10), @to_lsn binary(10); SET @from_lsn = sys.fn_cdc_get_min_lsn(N'HumanResources_Employee'); SET @to_lsn = sys.fn_cdc_get_max_lsn(); SELECT * FROM cdc.fn_cdc_get_all_changes_HumanResources_Employee(@from_lsn, @to_lsn, 'all'); GO