List available session properties with SHOW SESSION to see all configurable properties for the current session and their current values, defaults, and descriptions
Set a session property for the current connection using SET SESSION <property_name> = <value>; for example: SET SESSION join_distribution_type = 'BROADCAST' to force broadcast joins, or SET SESSION task_concurrency = 16 to adjust per-task parallelism
For connector-specific session properties use the catalog-prefixed form: SET SESSION iceberg.split_manager_threads = 8 or SET SESSION hive.max_outstanding_splits = 500
For JDBC clients (e.g., DBeaver, BI tools), pass session properties via the JDBC connection URL using the sessionProperties parameter or by issuing SET SESSION statements immediately after connecting
Reset a session property to its default with RESET SESSION <property_name>; verify with SHOW SESSION the value has returned to the cluster default
Known gotchas
Session properties only persist for the duration of the current connection or transaction; they are not saved and must be re-applied for each new session — use a connection initialization script or wrapper in your application to apply them consistently
Some session properties (e.g., query_max_memory) are bounded by the cluster-level maximum set in config.properties; setting a session value higher than the cluster maximum has no effect and Trino silently uses the cluster cap
Connector session properties (catalog-prefixed) require the connector to explicitly declare them; if you set a non-existent property name Trino raises an error rather than ignoring it, which can break application startup scripts that set properties not available in the deployed Trino version
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