SET SESSION#
Synopsis#
SET SESSION name = expression
SET SESSION catalog.name = expression
Description#
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.
Examples#
The following example sets a system session property to enable optimized hash generation:
SET SESSION optimize_hash_generation = true;
The following example sets the incremental_refresh_enabled catalog session
property for a catalog using the Iceberg connector named example:
SET SESSION example.incremental_refresh_enabled=false;
The related catalog configuration property iceberg.incremental-refresh-enabled
defaults to true, and the session property allows you to override this setting
in for specific catalog and the current session. The
example.incremental_refresh_enabled catalog session property does not apply to
any other catalog, even if another catalog also uses the Iceberg connector.