Info Mart Merge Fail

[gustav]

Shot in the dark here, but has anyone had a Extract job fail due to primary key constraint violations in the stage database?

2009-01-09 09:06:41,666 WARN  Thread-196  55-23000 "database error.  Exception: ' (entityName=StgGIsLinkHistory,
....
Caused by: java.sql.BatchUpdateException: com.microsoft.sqlserver.jdbc.SQLServerException: Cannot insert duplicate key row in object 'dbo.STG_G_IS_LINK_HISTORY' with unique index 'PK_STG_G_IS_LINK_HISTORY'.

Im getting the same error on a number of stage tables.