Support more PostgreSQL features

[melkstam]

The underlaying driver used by encore to manage the is jackc/pgx which supports features such as copy from and batch queries. However, encore does not add support or forward the APIs for these features, something that would be nice to have.

[brentd]

I ran into this while working on a proof of concept with sqlc when it's configured with sql_package: pgx/v4. The code generated by sqlc expected me to provide a db struct matching an interface which has CopyFrom (and possibly other pgx-specific methods depending on what features of sqlc I use).

We have this in encore currently, which will return a *sql.DB compatible struct:

var db = sqldb.Named("inventory").Stdlib()

What might be nice to have is this to get a *pgx.Conn:

var db = sqldb.Named("inventory").Pgx()

The downside being that I understand using these would mean missing out on Encore's built-in tracing.

[eandre]

This is supported now with sqldb.Driver