Then leave that to Symfony docs and add a link to the docs in this recipe, because it's important to have server version.

The server version is important because else Doctrine performs a query to check server version and adapt container compilation depending on the server version.

Check Doctrine/DBAL/Platforms directory and see the different classes that can depend on the platform's version.

Let's include just one URL where the whole string - including serverVersion is explained... likely a symfony docs page as you said.

And if we don't have it already, what about a post install message that says to update the settings in this file?

I believe the need for this is removed in the next version of Doctrine?
refs doctrine/dbal#990 and doctrine/dbal#2671

Maybe :). Is the extra query to determine the version only run once when the container is being built? If so, paas will have a problem - they'll build the container before the db is ready. Or, is the extra query on every request? That's kind of lame, but more of a perf optimization. Or, does Doctrine run the query once at runtime and then cache it after? If that's the case, I don't see any reason to keep this.

If someone has a few minutes to run down those answers, that would help (I'm on my phone!)

The extra query is run only on container compilation to determine which driver/platform will be used by Doctrine IIRC

@Pierstoval If it's run on container compilation, then the serverVersion is probably needed... as you may be building the cache when you don't yet have access to the database. platform.sh is like this and I'm guessing that Heroku is as well. What I mean is: without the serverVersion, if the query is made at compile time, deploys would fail if you don't have database access at the time of building your container.

The need for the option should be solved in Doctrine DBAL (see the linked issues above).

No, the changes in DBAL does not remove the need for the serverVersion parameter. What it provides is a second guess attempt.

Closing because this was reworded as part of #258.