grails - Connect to H2 database using IntelliJ database client

Question

My Grails app uses a h2 database in dev mode (the default behaviour for Grails apps). The DB connection settings in DataSource.groovy are

dataSource {
    pooled = true
    jmxExport = true
    driverClassName = "org.h2.Driver"
    username = "sa"
    password = ""
    dbCreate = "create-drop" // one of 'create', 'create-drop', 'update', 'validate', ''
    url = "jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE"
}

I'm trying to setup a connection for this database using IntelliJ IDEA's database client tools. I start off creating the connection like so

Then in the following dialog, I enter the JDBC URL

And choose all available databases on the "Schemas & Tables" tab.

The "Test Connection" button indicates success, but as you can see from the red circle, no tables are found. It seems like I've correctly setup a connection to the h2 server, but not the schema itself.

BTW, I try to setup this connection once the app is running, so I'm sure that the schema/tables do actually exist.

Answer 1

Your configuration is for an h2:mem database. Memory Databases have no tables upon connecting to them, and any & all tables are lost when all the connections are closed. Furthermore, a (named) in memory database is unique to the JVM process that opens it. From the H2 documentation:

Sometimes multiple connections to the same in-memory database are required. In this case, the database URL must include a name. Example: jdbc:h2:mem:db1. Accessing the same database using this URL only works within the same virtual machine and class loader environment. (Emphasis added)

This means IDEA will create a unique devDb in its JVM (and classloader) space and your application will create a unique devDb in its JVM (and classloader) space. You can not connect to an in memory database from an external JVM process.

If you want to connect both your application and IntelliJ IDEA (or any other DB tool) to an H2 database at the same time, you will need to either

1. use an embedded database (that writes to a file) in your application and use Mixed Mode to allow IntelliJ IDEA (and/or other database tools) to connect to it
2. use a server mode database

See http://www.h2database.com/html/features.html#connection_modes for more information.