Wrong returned error type after rolling back an already committed transaction?

[LaCodon]

Hi everyone, I tried using pgx as a database/sql implementation and relied on the tx.Rollback function to return a sql.ErrTxDone (as defined here: https://pkg.go.dev/database/sql#pkg-variables) error in case the transaction has already been committed beforehand. However, the pgx transaction returns the custom ErrTxClosed error (

pgx/tx.go

Line 201 in 8f69e45

return ErrTxClosed

).

Is there a reason why the error from the database/sql package is not used or not even wrapped at least? Should we change that?

[jackc]

It's not used in pgx/tx.go because that code has nothing to do with database/sql. That is the pgx native interface. As far as I know, sql.ErrTxDone should only be returned from database/sql itself.

[LaCodon]

Oh okay, I get it. I assumed, that database/sql just passes the driver's errors through to the user but it actually has its own logic for tracking the transaction state and returns sql.ErrTxDone based on that (for reference: https://cs.opensource.google/go/go/+/master:src/database/sql/sql.go;l=2309;drc=c23579f031ecd09bf37c644723b33736dffa8b92).

Many thanks for your fast response!