Add an example for r2dbc connection URL

it was really difficult to figure out proper H2 r2dbc URL for a “file” database.

Eventually it worked as follows:

r2dbc:h2:file://././build/h2db/db/dbname;DB_CLOSE_DELAY=-1;USER=username

can we add a section on this, because I could not find this information anywhere and had to debug ConnectionFactoryProvider

[mp911de]

R2DBC H2 is basically a wrapper for H2 that attempts to bridge what H2 provides into the R2DBC world. The H2 documentation is really only a first starting point but it cannot cover how R2DBC URL’s get built.

You might be interested in the general URL scheme: https://r2dbc.io/spec/0.8.1.RELEASE/spec/html/#overview.connection.url

Basically, URL’s can contain the host part (“authority”) (r2dbc:h2:tcp://remote-host/database) or they can be built without (r2dbc:h2:file:///absolute/file/path) depending on what you’re trying to express. Getting feedback on the documentation and the idea how you approach configuration helps us to learn which aspects we can improve.

[62mkv]

thanks, Mark! so basically my problem was that I was trying to refer to “relative” file path, and a leading “.” was parsed as a “host”, which lead to problems later.

So I had to begin the path with that “././” thing. It might even be a defect, not just a documentation missing… I am not sure