Thanks for the quick reply. A few follow-up questions... On Sun, Feb 5, 2012 at 9:03 PM, Michael Bayer <mike...@zzzcomputing.com> wrote: > My first suggestion would be to just use cdecimal. That way performance > would not be an issue - I patch it in at program start time using the example > at > http://docs.sqlalchemy.org/en/latest/core/types.html#sqlalchemy.types.Numeric > . I've been using this approach in production financial applications for > several years without issue.
That looks ideal. I'll have to see about adding that to our systems. > If you use the Float() type, the Decimal will be coerced into a regular > float(), but you're looking for performance here so that's not the solution. Does that mean when I eventually I set up a table with a column of type Float(asdecimal=False), I'll still be hit by the conversion penalty as the read data is converted to a Decimal first by the connection, and then to a Float by whatever handles the columns? It sounds like yes. > There's not a public API right now to turn off this handling - it would imply > the _OracleNumeric type and other parts of the cx_oracle dialect would need > to be further complicated to support two modes of operation, and it was > enormously difficult to get precision numeric round trips as it is. A > monkeypatch that would force it off would be: > > engine = create_engine(...) > engine.dialect._to_decimal = float > > another way you could do it would be to use a connection pool event. Using > the connect event: > > from sqlalchemy import event > @event.listens_for(engine, "connect") > def connect(connection, rec): > connection.outputtypehandler = None > > Note that disabling the outputtypehandler will also mess up unicode handling, > unless you replace it with another output handler that returns a "unicode" > cursor.var(). I'm not too worried about unicode conversions. All the text in the database should be ASCII, and I've seen no attempts at unicode handling anywhere in the code base. If I do shut off the outputtypehandler on the connection, will that cause any other problems as I start adding Table objects with the appropriate Columns? Will the connection outputtypehandler be reset when it goes back into the pool? Or should I just keep one connection from returning to the pool solely for these old style queries? -- --Anthony -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
