Trino

Supported since 5.0.2.

Through the Trino (opens new window) connector, Ontop is able to construct VKGs on Trino databases.

Limitations & Exceptions

WARNING

Trino does not provide information about integrity constraints. Make sure to provide this information in order to avoid very inefficient queries. We recommend using lenses for this purpose.

• Accessing struct fields with the "dot operator" is not supported (see below).

Database Connection

The following shows the content of a sample .properties file that can be used to connect Ontop to Trino:

jdbc.url = jdbc:trino://localhost:8080/defaultdatabase
jdbc.user = user
jdbc.password = password
jdbc.driver = io.trino.jdbc.TrinoDriver

In case Trino is set up without authentication, the jdbc.user and jdbc.password lines can also be left out.

Nested Type Support

Ontop implements explicit compatibility with the Trino array type array(t). When used with the flatten lens, it is able to automatically infer the type of the result column.

The flatten lens cannot be used on arrays stored as JSON-encoded columns in the database. For such use cases, the column first has to be converted to an array type.

Struct Access

Individual MAP (opens new window) structures can be accessed by SQL expressions in the dialect's default way:

SELECT my_struct['my_attribute'] FROM ...

ROW (opens new window) structures can be accessed using the [position] operator. position must be an integer index starting from 1:

SELECT my_struct[1] FROM ...

WARNING

Accessing object fields using the "dot operator" is not supported. Please use the [] operator instead.