By default, Data Mover uses Teradata PT to perform partial copies on tables and views. The WHERE clause provided in the job definition is appended to the SELECT statement used by the Teradata PT export operator when exporting data from the source system. The Teradata PT load, update, or stream operator is used to insert the partial data into the target system.
If the target table already exists and is not empty, Data Mover creates a target staging table and places the data there first. After the partial data is loaded on to the target staging table, Data Mover uses the key columns provided in the job definition to determine which rows are being updated and which rows are new and can be inserted. The target staging table is dropped once all of the data is in the target table.
You can use Teradata QueryGrid to perform partial copies on tables or views by specifying a foreign server in the job definition. The partial copy performs in the same manner as Teradata PT, except with Teradata QueryGrid being used to copy the partial data from the source system to the target system.
You can use DSA to perform partial copies for tables and views by telling Data Mover to use a source staging table. When a source staging table is used, Data Mover first creates a source staging table, then copies the partial data into that table. Then, DSA copies the full source staging table to the target system. If the target table already exists and is not empty, the source staging table is copied into a target staging table where the data can be transferred over into the target table using the same methods as Teradata PT.