Re: sth->prepare() setting Active?

On Fri, Sep 30, 2016 at 12:40:02AM +0100, Russell Howe via dbi-users wrote:
> On Thu, Sep 29, 2016 at 11:30:08PM -0000, Greg Sabino Mullane wrote:
> > 
> > > Should a call to prepare() return an Active statement? (i.e. $sth->{Active} == 1)
> > >
> > > This appears to be the behaviour of DBD::Sybase, but not DBD::Pg
> > 
> > I don't think there is a canonical answer to that, but I can say that 
> > DBD::Pg in most cases will not even talk to the server until the first 
> > execute() after the prepare(), so it not being Active seems a sane 
> > interpretation.

> > The docs for DBD::Pg:
> > 
> >    Indicates if a handle is active or not. For database handles, this 
> >    indicates if the database has been disconnected or not. For statement 
> >    handles, it indicates if all the data has been fetched yet or not. 
> >    Use of this attribute is not encouraged.
> > 
> > As far as I can tell, DBD::Sybase makes not effort to do anything special 
> > regarding that attribute.
> 
> DBD::Sybase has this
> 
>     /* Re-enable the active flag here (in 1.05_03) to fix bug with
>        finish not getting called correctly */
>     DBIc_ACTIVE_on(imp_sth);
> 
> at the end of syb_st_prepare() in dbdimp.c
> 
> So, it explictly sets Active to deal with some issue that I haven't
> fully delved into.
> 
> > In short, I would not rely upon it, especially across DBDs.
> 
> That's unfortunate, because Class::DBI does.
> 
> $ grep -r Active .
> ./lib/Class/DBI.pm:		$sth->execute(@$args) unless $sth->{Active};
> 
> (from sth_to_objects)
> 
> As far as I can see, this is to work out whether the sth that's been
> passed in has already had execute called on it (e.g. part of a multiple
> result loop). Removing the $sth->{Active} check (and ensuring Ima::DBI
> always calls prepare and not prepare_cached (I haven't figured out what's
> going on there yet) gets Class::DBI working with DBD::Sybase.
> 
> Our current code overrides db_Main which seems like an unnecessary hack
> to me, and confuses Class::DBI somewhat, triggering warnings.
> 
> I'm halfway down this rabbit hole and not really sure which turning to
> take now!

I'd take the view that $sth->{Active} shouldn't be true until after a
successful execute().

I'd happily take a doc patch that tightens up the docs in that direction.

Tim.