With its thread support, Ingres has long supported the concurrent execution of separate queries. For short OLTP style queries, this permits a many fold increase in the number of such queries that can be executed in a given unit of time.

Ingres has the additional capability to split up the execution of individual long running queries over multiple threads. This parallel execution of a single complex query reduces the time to execute it.

Parallel query plans are implemented in Ingres by the introduction of the exchange node type. For more information, see Sample Parallel QEPs.

An exchange node marks the boundary between processing threads in a query plan. It can spawn one or many threads to execute the query plan fragment below the exchange node concurrent with the fragment above the exchange node. The exchange node itself passes or exchanges rows from threads below the node to the thread above the node.