Connection pooling in slick?

Question

Is there an easy way to use a DB connection pool with scala's Slick?

Answer 1

I use Apache Commons DBCP for this. Basically, you simply create a DataSource, that encapsulates the pooling details, and pass that DataSource to Slick:

import org.apache.commons.dbcp.BasicDataSource

val dataSource: DataSource = {
  val ds = new BasicDataSource
  ds.setDriverClassName("org.hsqldb.jdbc.JDBCDriver")
  ds.setUsername("SA")
  ds.setPassword("")
  ds.setMaxActive(20);
  ds.setMaxIdle(10);
  ds.setInitialSize(10);
  ds.setValidationQuery("SELECT 1 FROM INFORMATION_SCHEMA.SYSTEM_USERS")
  new java.io.File("target").mkdirs // ensure that folder for database exists
  ds.setUrl("jdbc:hsqldb:file:target/db/db")
  ds
}

// test the data source validity
dataSource.getConnection().close()

// get the Slick database that uses the pooled connection
val database = Database.forDataSource(dataSource)

This example uses HSQLDB, but can be easily adapted to any other database.

Full example is here (you can clone the project, and run sbt run in lift/ directory to see it working).