You can run table operators on a set of AMPs based on a contiguous or sparse map that is associated with the table operator. The database distributes input rows to the AMPs in the specified or default map before running the table operator on the specified or default map if the input rows are not already distributed per that map.
For example, you may want to configure a few nodes with extra memory so that those nodes can run special table operator queries, such as SQL-H queries, SAS jobs, or R scripts. You can define a map that includes only the AMPs on the special nodes and then specify that map in a CREATE/REPLACE FUNCTION statement using the EXECUTE MAP clause.
You can also use the EXECUTE MAP clause when invoking a table operator so that the table operator will execute only on the AMPs specified in the map. This overrides any map and colocation name specified when the table operator was created.
For more information, see CREATE FUNCTION (Table Form) information in Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144 and FROM clause of the SELECT statement in Teradata Vantage™ - SQL Data Manipulation Language, B035-1146.