Two areas of the database have been enhanced:
- User and role mapping in the database has been enhanced to support QueryGrid user mapping.
- The staging and transfer of data to and from remote tables has been optimized.
The user and role mapping changes simplify the mapping of local users to remote users in QueryGrid by allowing a DBA to create a mapping table. DBAs can then create dynamic server objects that are customized based on the connected user or the session.
The custom USING clauses in all table operators, including those used in QueryGrid, now support the following Teradata system variables:
- DATE and CURRENT_DATE
- ROLE and CURRENT_ROLE
- TIME and CURRENT_TIME
- USER and CURRENT_USER
Custom USING clauses in QueryGrid table operators now also support the use of scalar subqueries.
The optimization of data transfer to and from remote tables reduces network overhead for running remote queries and typically improves query performance. This benefit is achieved by the database's ability to push aggregations, joins, and joins between a local and a remote table onto the remote system whenever it is deemed beneficial. By reducing the amount of data to be transferred, it avoids unnecessary use of memory and processor resources on Teradata servers for staging data.
QueryGrid users can now use Teradata system variables and scalar subqueries in custom USING clauses.
Database users not running QueryGrid can now use Teradata system variables in custom USING clauses with all table operators.
You must use Teradata QueryGrid to take advantage of some of these enhancements.
For additional information about Teradata QueryGrid, see the individual Teradata QueryGrid user guides and installation guides that are compatible with Teradata Database 16.00.
For additional information about support for Teradata system variables in the USING clause, see SQL Functions, Operators, Expressions, and Predicates, B035-1145.