To redistribute input table rows to fewer AMPs, sparse map can be used. For example, to redistribute a table to four AMPs, first create a sparse map of four AMPs named sparse_map_4 using the following command:
CREATE MAP sparse_map_4 FROM td_map1 SPARSE ampcount=4;
Then, create a table using this sparse map, as follows.
CREATE TABLE Table1, MAP=sparse_map_4 (a1 INTEGER, b1 INTEGER) PRIMARY INDEX (a1);
All data inserted into this table is distributed to four AMPs only.
For more information about maps, see Teradata® Database SQL Data Definition Language - Syntax and Examples, Teradata Vantage™ - Database Design, and Teradata Vantage™ - Database Administration.