15.00 - Multistatement Request Parallelism - Teradata Database

Teradata Database Design

Teradata Database
User Guide

Multistatement Request Parallelism

Multistatement requests are a Teradata SQL extension that bundle any number of distinct SQL statements together in such a way that the Optimizer treats them as a single unit. Teradata Database always attempts to perform the SQL statements in a multistatement request in parallel. An example of multistatement parallelism is common subexpression elimination, an operation in which the Optimizer collapses any subexpressions that are common to the SQL statements in the request and performs the extracted operation one time only.

For example, suppose you bundle six SELECT statements together in one multistatement request, and each contained a common subquery. That common subquery is executed only once and the result substituted back into the respective individual select operations.

Even though the individual SQL statements within a multistatement request are performed in an interdependent, overlapping set of operations, each returns its own, distinct answer set.