[egenix-users] On demand connect

[M.-A. Lemburg]

F.Baart at SFK.NL wrote:
> Dear egenix users,
> 
> 
> I use mx.ODBC.Zope DA 1.0.8  with mysql 4.0.14 on zope 2.6.1.  Once in a
> while I get the following error message while executing a query from zope:
> 
> 
> Error Type: ProgrammingError
> Error Value: ('HY000', 2013, '[MySQL][ODBC 3.51
> Driver][mysqld-4.0.14-standard]Lost connection to MySQL server during
> query', 5923)
> 
> 
> I found that this happens when no query has been executed for 1800 seconds
> (mysql wait-timeout variable). I also get this message when I manually kill
> the connection from mysql. If I execute the same query again it will run
> succesful.
> 
> 
> I thought that using the "Use Connect on Demand" option would reconnect to
> mysql automaticly. It does reconnect but only after raising a
> ProgrammingError at the first query which gets excecuted after a lost
> connection.
> 
> 
> Does anybody know how to fix this?

The Zope DA automatically reconnects in case it gets an
OperatingError from the database (which is what the database
driver should generate for these kinds of errors).

The error that MySQL uses a generic error HY0000 which could
be anything from connection problems to interface problems
or programming errors. The driver *should* have sent HYT00
or HYT01.

The next version of the Zope DA will have an option that
allows doing an alive check on the connection before trying
to execute a statement (more expensive, but needed
in order to support auto-reconnect with some ODBC
drivers).

Another thing you could try is report this as bug to MySQL
and have them generate the correct error code for the
timeout.

-- 
Marc-Andre Lemburg
eGenix.com

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