On Tue, Jul 27, 2004 at 02:13:03AM +0200, Jochen Wiedmann wrote: > Henri Asseily wrote: > > >I'm trying to do the following, and was wondering where I should look > >to get a good handle on what's going on: > > > >I have an $sth that's pointing to a dead server. > >I have a new $sth2 that's pointing to a good server. > > > >upon the user doing $sth->execute, I want to be able to get $sth > >pointing to $sth2, effectively making $sth valid again. > > > >I understand that $sth is a tied hash. Can it be cleanly untied and > >retied to what $sth2 is tied to? Would that do what I'm looking to do? > >I have no problem coding up some C, as long as I can be pointed at the > >relevant code in dbi.
I've long had a plan to provide such methods. You'll see it mentioned in http://search.cpan.org/src/TIMB/DBI-1.43/ToDo as $h->swap_internal_handle($other_h) or $sth->become($sth2) It's probably fairly trivial if you're familiar with perl internals enough to know to use mg_find(SvRV(h),'P') and why you'd need to. You'll also need DBIc_MY_H(imp_xxh). I'd happily accept a patch (that includes tests). > I think your problem can be solved much simpler: > > - Write a pure Perl DBD driver, roughly comparable to DBD::Proxy. > - Your Perl DBD drivers classes (dbh, sth) would use references to the > actual handles internally. > - Whenever required, update the internal handles. > > It's quite possible, that a similar solution already exists, for example > DBD::Multiplex or however it is called. DBD::Multiplex ought to be a good place to do this, but it's mid-rewrite so I can't recommend working on the available source. Tim.
