System connector
The System connector provides information and metrics about the currently running Trino cluster. It makes this available via normal SQL queries.
Configuration
The System connector doesn't need to be configured: it is automatically
available via a catalog named system.
Using the System connector
List the available system schemas:
SHOW SCHEMAS FROM system;
List the tables in one of the schemas:
SHOW TABLES FROM system.runtime;
Query one of the tables:
SELECT * FROM system.runtime.nodes;
Kill a running query:
CALL system.runtime.kill_query(query_id => '20151207_215727_00146_tx3nr', message => 'Using too many resources');
System connector tables
metadata.catalogs
The catalogs table contains the list of available catalogs.
metadata.schema_properties
The schema properties table contains the list of available properties that can be set when creating a new schema.
metadata.table_properties
The table properties table contains the list of available properties that can be set when creating a new table.
metadata.materialized_views
The materialized views table contains the following information about all materialized views:
| Column | Description |
|---|---|
catalog_name | Name of the catalog containing the materialized view. |
schema_name | Name of the schema in catalog_name containing the materialized view. |
name | Name of the materialized view. |
storage_catalog | Name of the catalog used for the storage table backing the materialized view. |
storage_schema | Name of the schema in storage_catalog used for the storage table backing the materialized view. |
storage_table | Name of the storage table backing the materialized view. |
is_fresh | Flag to signal if data in the storage table is up to date. Queries on the materialized view access the storage table if true, otherwise the definition is used to access the underlying data in the source tables. |
owner | Username of the creator and owner of the materialized view. |
comment | User supplied text about the materialized view. |
definition | SQL query that defines the data provided by the materialized view. |
metadata.materialized_view_properties
The materialized view properties table contains the list of available properties that can be set when creating a new materialized view.
metadata.table_comments
The table comments table contains the list of table comment.
runtime.nodes
The nodes table contains the list of visible nodes in the Trino cluster along with their status.
runtime.optimizer_rule_stats
The optimizer_rule_stats table contains the statistics for optimizer
rule invocations during the query planning phase. The statistics are
aggregated over all queries since the server start-up. The table
contains information about invocation frequency, failure rates and
performance for optimizer rules. For example, you can look at the
multiplication of columns invocations and average_time to get an
idea about which rules generally impact query planning times the most.
runtime.queries
The queries table contains information about currently and recently running queries on the Trino cluster. From this table you can find out the original query SQL text, the identity of the user who ran the query, and performance information about the query, including how long the query was queued and analyzed.
runtime.tasks
The tasks table contains information about the tasks involved in a Trino query, including where they were executed, and how many rows and bytes each task processed.
runtime.transactions
The transactions table contains the list of currently open transactions and related metadata. This includes information such as the create time, idle time, initialization parameters, and accessed catalogs.
System connector procedures
runtime.kill_query(query_id, message)
Kill the query identified by query_id. The query failure message
includes the specified message.
SQL support
The connector provides globally available and read operation statements to access Trino system data and metadata.