Query Runner

What is a QueryRunner?

Each new QueryRunner instance takes a single connection from the connection pool, if the RDBMS supports connection pooling. For databases that do not support connection pools, it uses the same connection across the entire data source.

Creating a new QueryRunner instance

Use the createQueryRunner method to create a new QueryRunner:

const queryRunner = dataSource.createQueryRunner()

Using QueryRunner

After you create a new instance of QueryRunner, use the connect method to get a connection from the connection pool:

const queryRunner = dataSource.createQueryRunner()
await queryRunner.connect()

Important: Make sure to release it when it is no longer needed to make it available to the connection pool again:

await queryRunner.release()

After the connection is released, you cannot use the query runner's methods.

QueryRunner has a bunch of methods you can use, it also has its own EntityManager instance, which you can use through manager property to run EntityManager methods on a particular database connection used by QueryRunner instance:

const queryRunner = dataSource.createQueryRunner()

// take a connection from the connection pool
await queryRunner.connect()

// use this particular connection to execute queries
const users = await queryRunner.manager.find(User)

// remember to release the connection after you are done using it
await queryRunner.release()