Re: Nested Transactions, Abort All

Bruce,

> They have no way of reporting a failed query back to the user? How do
> people program in those environments? Right now any failed query aborts
> the transaction so it seems it would be pretty easy.

Believe it or not, PHP4 doesn't. This is one of the reasons why coders in
other languages don't consider PHP a "real" programming language; the lack of
exception handling. However, given this limitation we can't really use NTs
in PHP4 anyway, so it's sort of a moot point. Sorry for bringing it up.

To my current knowledge (and hopefully Andrew will speak up if I'm wrong) the
DBD::Pg driver reports back a query exception, but not the SQLSTATE. This
means that we can detect an abort (assuming all exceptions are aborts) but
not what caused the abort, except by parsing the error message for text -- a
hazardous approach at best. But you would be right to point out that this is
a problem with the DBD::Pg driver.

There are, however, other client applications where the problem is more
ingrained. I've done an application for ColdFusion recently, and discovered
that CF is completely unable to detect even the limited error-reporting
capability of ODBC. This means that if CF can't query it, it doesn't exist.

> Well, that involves either creating a conditional capability in the
> backend, or in psql, neither of which will happen for 7.5. The best we
> can do is allow COMMIT NESTED INGORE ERROR (or COMMIT NESTED INGORE
> ROLLBACK) and just let the script keep going. I am thinking of cases
> where you want to drop an object you aren't sure exists in a
> transaction. Anything more complicated like issuing a replacement query
> will have to wait for 7.6.

OK, I didn't realize that it was a difficult thing. I think it should go on
the TODO list but you are the judge of what's a quick fix and what's not.

(BTW, aside from this limitation, I am *not* in favor of COMMIT NESTED IGNORE
ERROR)

--
-Josh Berkus
Aglio Database Solutions
San Francisco