Transactions

Transactions are part of the request's ctx. This prevents the need to add a transaction parameter to each method, keeping the method signatures smaller. And as a transaction is typically tied to a http request, it makes sense to include it into the requests context.

The transaction is saved with the key postgres.CtxTX

Jobs are setting the transaction automatically, so you can make changes inside the same transaction as the job itself is running on.
Usecases need to decorated explicitly. Use the decorators app.NewTxRequest() and app.NewTxCommand().