File content logging during execution of COPY queries (was: Better logging of COPY queries if log_statement='all')

> > > According to my colleagues it would be very nice to have this feature.
> > > For instance, if you are trying to optimize PostgreSQL for application
> > > that uses COPY and you don't have access to or something like this.
> > > It could also be useful in some other cases.
> >
> > This use-case doesn't really make much sense to me. Can you explain it
> > in more detail? Is the goal here to replicate all of the statements
> > that are changing data in the database?
>
> The idea is to record application workload in real environment and write
> a benchmark based on this record. Then using this benchmark we could try
> different OS/DBMS configuration (or maybe hardware), find an extremum,
> then change configuration in production environment.
>
> It's not always possible to change an application or even database (e.g.
> to use triggers) for this purpose. For instance, if DBMS is provided as
> a service.
>
> Currently PostgreSQL allows to record all workload _except_ COPY
> queries. Considering how easily it could be done I think it's wrong.
> Basically the only real question here is how it should look like in
> postgresql.conf.

OK, how about introducing a new boolean parameter named log_copy?
Corresponding patch is attached.

--
Best regards,
Aleksander Alekseev