enable sort-merge joins and JTC

Summary information

Default value

0

Range of values

0–1

Status

Dynamic

Display level

Comprehensive

Required role

System Administrator

enable sort-merge joins and JTC configuration parameter determines whether merge joins and join transitive closure are considered by the query optimizer. By default, merge joins and join transitive closure are not enabled. To enable merge joins, set this parameter to 1.

Merge joins and join transitive closure can improve performance for queries that access large amounts of data, but increase optimization time. The session-level options set sort-merge on and set jtc on take precedence over the server-wide setting. For more information, see “Enabling and disabling merge joins” on page 468 and “Enabling and disabling join transitive closure” on page 468 in the Performance and Tuning Guide.