SET SESSION name = expression
SET SESSION = expression


Set a session property value or a catalog session property.

Session properties#

A session property is a configuration property that can be temporarily modified by a user for the duration of the current connection session to the Trino cluster. Many configuration properties have a corresponding session property that accepts the same values as the config property.

There are two types of session properties:

  • System session properties apply to the whole cluster. Most session properties are system session properties unless specified otherwise.

  • Catalog session properties are connector-defined session properties that can be set on a per-catalog basis. These properties must be set separately for each catalog by including the catalog name as a prefix, such as catalogname.property_name.

Session properties are tied to the current session, so a user can have multiple connections to a cluster that each have different values for the same session properties. Once a session ends, either by disconnecting or creating a new session, any changes made to session properties during the previous session are lost.


The following example sets a system session property to enable optimized hash generation:

SET SESSION optimize_hash_generation = true;

The following example sets the optimize_locality_enabled catalog session property for an Accumulo catalog named acc01:

SET SESSION acc01.optimize_locality_enabled = false;

The example acc01.optimize_locality_enabled catalog session property does not apply to any other catalog, even if another catalog also uses the Accumulo connector.

See also#