Use SimpleDriverDataSource when creating a Liquibase-specific DataSource

[wmilewski]

Hi,

When Liquibase creates a new DataSource instance, the connection pool size is always 10, presumably a default value. This is not always desirable. It is possible to specify a custom DataSource for Liquibase to use, but setting it up is not trivial, at least for newcomers to SpringBoot and Liquibase. I think it would be much easier to allow developers to change the pool size by setting a custom value e.g. in the application.properties file.

Would there be an interest in adding this new configuration property? If yes, I'd be happy to try and provide a PR.

[wilkinsona]

This was proposed and rejected in the past in favour of @LiquibaseDataSource. Rather than adding more properties, we could avoid using a connection pool altogether. This is what Flyway does, creating an instance of its DriverDataSource when configured with a JDBC URL, username and password. We could do similar using Spring Framework's SimpleDriverDataSource.

Let's see what the rest of the team thinks.

We already have support for falling back to SimpleDriverDataSource when there's no connection pool available. This branch changes the auto-configuration so that it uses SimpleDriverDataSource whenever a DataSource is being created.

[wmilewski]

Thanks @wilkinsona. It makes sense now that I understand this is by design. An alternative could be to improve the documentation, perhaps with a code sample.

[wilkinsona]

We're going to switch to using SimpleDriverDataSource when we create a Liquibase-specific DataSource. We can't see any need for a connection pool to be used and this will align the behaviour with what happens when using Flyway.