PostgreSQL driver: preparedQueries control

Hi there,

After having some issues with prepared statements tripping up Qt with PostgreSQL and PGpool, due to frequently lost database connections from mobile phones, I found that the easiest way to stop the hassle was to simply disable "preparedQueriesEnabled" in the driver (see attached "patch").

Now, in case you guys are having a really boring winter day in the future, then I would like to suggest to make preparedQueriesEnabled user-controllable, by adding a little something to the driver, like "driver->preparedQueriesEnabled(true/false)".

In cases like mine, where I do not have to worry about SQL injections or performance penalties, but constantly face unstable database connections, it adds to overall app robustness to be able to turn off prepared statements. Doing so without having to touch the driver code itself would be great. 

Many thanks,

Holger