[Question] Exposing internal types.

[achille-roussel]

Issue description

I'd like to know if the maintainers of this package would be open to expose internal types to allow the driver to be integrated with more than the standard database/sql package?

One of the upsides would be the ability to bypass database/sql on hot code paths to work around the inefficiencies of its design (using interfaces causes massive amounts of extra dynamic memory allocations).

I'll be happy to submit a pull request to make this change if you guys feel like this would be a good change to make.

Example code

Here's how I imagine one could use it:

// Adding this method to the driver would allow the program to open a MySQL connection
// which it would have to maintain, but now it has access to a concrete type which gives
// opportunities for the compiler to generate more efficient code wherever it is used.
func (MySQLDriver) OpenConn(ctx context.Context, dsn string) (*Conn, error) {
  ...
}

[julienschmidt]

We're already exposing the MySQLDriver struct to be able to work around limitations of database/sql.
As long if it doesn't make the driver much more complicated, I am open to it.

[achille-roussel]

Yes, MySQLDriver is exposed but the Open method returns driver.Conn interface, which means the compiler has no idea what the actual concrete type is, and therefore escape analysis fails when passing values as arguments to the methods.

If the actual connection type (and a few other) were exposed it gives the compiler opportunities to generate more efficient code.

Thanks for your response, I'll experiment with it and try to come up with a pull request.