On 7/18/07, Richard Jolly <[EMAIL PROTECTED]> wrote:
On 18 Jul 2007, at 20:26, Brandon Black wrote:> Well, I've tracked this down a little bit further now. I had poorly > assumed $dbh->{AutoCommit} would statically remain at whatever value > it was set to (or defaulted to) at DBI->connect time. As it turns > out, $dbh->begin_work turns off the $dbh->{AutoCommit} value, which is > what's causing the confusion. We noticed this recently as well. Probably should have provided more hints in my original mail :( from DBI.pm: sub begin_work { my $dbh = shift; return $dbh->set_err(1, "Already in a transaction") unless $dbh->FETCH('AutoCommit'); $dbh->STORE('AutoCommit', 0); # will croak if driver doesn't support it $dbh->STORE('BegunWork', 1); # trigger post commit/rollback action return 1; } I'm wondering why DBI turns off autocommit rather than issuing a BEGIN WORK statement - but I guess that's for the DBI list. It appears to be so as to provide consistent behaviour/interface at the DBI level. We were thrown off for a while because the DBIx::Class::Storage::Statistics logging shows a 'BEGIN WORK'. Both DBI and D::C::S::S document the behaivour, but it is just counter-intuitive enough that it's easy to overlook. Thanks for the speedy response,
I've patched trunk now with what I had plus a few more little tidbits (mostly to the tests themselves), I think this clears up the basic issues we're having. I'm still not fully confident that rollbacks work right in nested transactions in all cases. Certainly the "NESTED_ROLLBACK_EXCEPTION" exception isn't being thrown when it used to be, and there were never any tests for that anyways. I'm not really confident that I even understand the point of that special exception, or fathom what the most correct behavior is in a failed nested (fakely nested) transaction. The way I've got it running right now, in the case of txn_do, "inner" transactions are completely fake, and any exception will propagate normally to the outermost txn_do. Obviously in the case of people manually using txn_begin, it's up to what they're doing with their eval constructs. Does anyone remember exactly what the original design of nested txn_begin/txn_do + NESTED_ROLLBACK_EXCEPTION was supposed to work like? Without tests it's hard to say. Josef's branch for mysql nested transactions using savepoints is quite out of date, but when I next get back to this, I'll look at his diffs and see if we can't get nesting nailed down for all cases (fake nesting as a default, and savepoints on DBs that support it). Savepoints appear to support arbitrary nesting on Pg and MySQL. -- Brandon _______________________________________________ List: http://lists.rawmode.org/cgi-bin/mailman/listinfo/dbix-class Wiki: http://dbix-class.shadowcatsystems.co.uk/ IRC: irc.perl.org#dbix-class SVN: http://dev.catalyst.perl.org/repos/bast/trunk/DBIx-Class/ Searchable Archive: http://www.mail-archive.com/dbix-class@lists.rawmode.org/
