starrocks/contrib/trino-connector

StarRocks connector

This is a connector for StarRocks that is compatible with Trino. The connector allows querying and inserting in an external StarRocks instance. This can be used to join data between different systems like StarRocks and Hive, or between two different StarRocks instances.

Requirements

To connect to StarRocks, you need:

• StarRocks 2.5.0 or higher.
• Network access from the Trino coordinator and workers to StarRocks. Port 9030 and 8030 are the default port.

Configuration

To configure the StarRocks connector, create a catalog properties file in etc/catalog named, for example, example.properties, to mount the StarRocks connector as the starrocks catalog. Create the file with the following contents, replacing the connection properties as appropriate for your setup:

connector.name=starrocks
connection-url=jdbc:mysql://starrocks:9030
connection-user=root
connection-password=
starrocks.client.load-url=starrocks:8080

The connection-url defines the connection information and parameters to pass to the MySQL JDBC driver. The connection-user and connection-password are typically required and determine the user credentials for the connection, often a service user. You can use secrets to avoid actual values in the catalog properties files.

The following table describes configuration properties for connection credentials:

Property name	Required	Default value	Description
connector.name	Yes	NONE	Connector name.
connection-url	Yes	NONE	Connection information and parameters.
connection-user	Yes	NONE	Connection user name.
connection-password	Yes	NONE	Connection password.
starrocks.client.load-url	Yes	NONE	The address that is used to connect to the HTTP server of the FE. You can specify multiple addresses, which must be separated by a semicolon (;). Format: <fe_host1>:<fe_http_port1>;<fe_host2>:<fe_http_port2>.
starrocks.client.label-prefix	No	trino-	The label prefix used by Stream Load.
starrocks.client.max-cache-bytes	No	268435456	The maximum size of data that can be accumulated in memory before being sent to StarRocks at a time. The maximum value ranges from 64 MB to 10 GB, the default value is 256MB.
starrocks.client.connect-timeout	No	30000	The timeout for establishing HTTP connection. Valid values: 100 to 60000. Unit: ms, the default value is 30000.

Multiple StarRocks servers

You can have as many catalogs as you need, so if you have additional StarRocks servers, simply add another properties file to etc/catalog with a different name, making sure it ends in .properties. For example, if you name the property file sales.properties, Trino creates a catalog named sales using the configured connector.

Type mapping

Because Trino and StarRocks each support types that the other does not, this connector modifies some types when reading or writing data. Data types may not map the same way in both directions between Trino and the data source. Refer to the following sections for type mapping in each direction.

StarRocks to Trino type mapping

The connector maps StarRocks types to the corresponding Trino types following this table:

StarRocks type	Trino type	Notes
BOOLEAN	TINYINT
TINYINT	TINYINT
SMALLINT	SMALLINT
INT	INTEGER
BIGINT	BIGINT
LARGEINT	DECIMAL(20, 0)
DECIMAL(p, s)	DECIMAL(p, s)
DOUBLE	DOUBLE
FLOAT	REAL
CHAR(n)	CHAR(n)
STRING	VARCHAR(65533)
VARCHAR(n)	VARCHAR(n)
BINARY, VARBINARY	VARBINARY
DATE	DATE
DATETIME	TIMESTAMP(0)
JSON	JSON

Trino to StarRocks type mapping

The connector maps StarRocks types to the corresponding Trino types following this table:

Trino type	StarRocks type	Notes
BOOLEAN	BOOLEAN
TINYINT	TINYINT
SMALLINT	SMALLINT
INTEGER	INT
BIGINT	BIGINT
REAL	FLOAT
DOUBLE	DOUBLE
DECIMAL(p, s)	DECIMAL(p, s)
VARCHAR(n)	VARCHAR(n)
VARCHAR(0)	VARCHAR(65533)
CHAR(n)	CHAR(n)
VARBINARY	VARBINARY
JSON	JSON
DATE	DATE
TIMESTAMP(0)	DATETIME

No other types are supported.

Type mapping configuration properties

The following properties can be used to configure how data types from the connected data source are mapped to Trino data types and how the metadata is cached in Trino.

Property name	Description	Default value
upsupported-type-handling	Configure how unsupported column data types are handled: IGNORE, column is not accessible. CONVERT_TO_VARCHAR, column is converted to unbounded VARCHAR. The respective catalog session property is unsupported_type_handling.	IGNORE

Querying StarRocks

The StarRocks connector provides a schema for every StarRocks database. You can see the available StarRocks databases by running SHOW SCHEMAS:

SHOW SCHEMAS FROM starrocks;

If you have a StarRocks database named example, you can view the tables in this database by running SHOW TABLES:

SHOW TABLES FROM starrocks.example;

You can see a list of the columns in the clicks table in the example database using either of the following:

DESCRIBE starrocks.example.clicks;
SHOW COLUMNS FROM starrocks.example.clicks;

Finally, you can access the clicks table in the example database:

SELECT * FROM starrocks.example.clicks;

If you used a different name for your catalog properties file, use that catalog name instead of starrocks in the above examples.

SQL support

The connector provides read access and write access to data and metadata in the StarRocks database. In addition to the globally available and read operation statements, the connector supports the following statements:

• INSERT
• DELETE
• TRUNCATE
• DROP TABLE
• CREATE SCHEMA
• DROP SCHEMA

SQL DELETE

If a WHERE clause is specified, the DELETE operation only works if the predicate in the clause can be fully pushed down to the data source.

Fault-tolerant execution support

The connector does not support Fault-tolerant execution of query processing.