[Zope-DB] dealing with dropped database connections

Charlie Clark charlie at egenix.com
Wed Jan 18 09:34:13 EST 2006

On 2006-01-18 at 15:17:24 [+0100], martin f krafft <madduck at madduck.net> 
> also sprach Charlie Clark <charlie at egenix.com> [2006.01.18.1451 +0100]:
> > This problem is common to all ZopeDA's connected to network data
> > sources.  You might want to try using our mxODBCZopeDA with the option
> > "Connect on demand" which often helps in these situations.
> Interesting pointer, thanks a lot!
> I wonder how this product determines that a stalled connection
> cannot fulfill a demand.
> > However, a lot depends on how your data source and driver are
> > configured as the "stale" connection is often serialised even
> > though it has been lost.
> I am not sure what you mean with that. Most transactions are
> serialised by default these days. I don't understand what that has
> to do with stalled connections.
> But you did write serialised *connections*. What are those?

Running ODBC over a network involves a lot of components. Assuming there is 
a network problem causing the connection to fail but the network 
subsequently recovers, it is possible that the DB driver is in the same 
state as the ZopeDA and does not discard the previous connection. Unless it 
does this then the ZopeDA will not attempt to make a new connection. ie, 
There are limits about what you can do in ZopeDA's because of Zope's 


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