Re: [Webware-discuss] SteadyDB and cx_Oracle

[Christoph Z. <ci...@on...>]

Matthew J Harriger wrote:
> I am using just the SteadyDB module from DBUtils to provide fault-tolerant 
> connections to an Oracle database using cx_Oracle as the dbapi2 module. If 
> a client loses its network connection (network cable unplugged, out of 
> range of the wireless network, etc.), and then re-establishes the 
> connection, all Oracle connections and cursors that were open become 
> invalid. Trying to execute a statement with one of those cursors returns 
> an ORA-03114 NOT CONNECTED TO ORACLE error, which causes cx_Oracle to 
> raise an exception of class DatabaseError. However, SteadyDB only tries to 
> recover from OperationlError and InternalError exceptions(SteadyDB.py, 
> lines 238 and 338). Any chance that SteadyDB could be changed in future 
> versions to also recover from DatabaseErrors? Or perhaps there could be a 
> mechanism for advanced users to set what exception types SteadyDB tries to 
> recover from? Should I submit this as a bug?

DatabaseError is very unspecific: I think cx_Oracle should really raise 
an OperationalError instead.

I have noted this problem and will try myself next time I come across 
Oracle again.

Can you also double check if it's really a DatabaseError and maybe ask 
the cx_Oracle folks whether this is intended? I currently only see they 
raise InterfaceErrors which would also be a problem:
http://cx-oracle.svn.sourceforge.net/viewvc/cx-oracle/trunk/Connection.c?view=markup

Making the error classes configurable is also a good idea, but we need 
to find a good default set and and I'd also like to see cx_Oracle fixed 
since I think OperationlError is the only correct exception for 
connection loss (the InternalError was already a concession).

-- Christoph