Lazy connections

[sonic182]

db_connection supports lazy pools?

I mean, create connections by demand and close them if idle

[josevalim]

That's not a decision imposed by db_connection. You can async/lazily connect, but you implement it in your callbacks.

[sonic182]

Is there any example of that?

it is complicated to specify a custom pool module for opts in Repo, it is heavy sticket to the one implemented here in db_connection and the Holder

[josevalim]

Look at Postgrex. It attempts to connect on init, but if it fails, it does so asynchronously. The same principle could be used for laziness. It is a matter of not doing it on init but when the callbacks are invoked.