[okfn-help] vdm: strange behavior

Wed Sep 8 14:20:23 BST 2010

Hoi,

On Wed, Sep 8, 2010 at 12:38 PM, Rufus Pollock <rufus.pollock at okfn.org> wrote:

>> I'm not sure I'm not reading this out of order, but I've reported
>> already a while ago that I created a special type for SQLAlchemy that
>> stores a higher-precision datetime as a decimal.
>
> But won't this require migrations for all systems currently using VDM
> in that you are changing the underlying type (i.e. from datetime to a
> decimal).

I'm proposing this is only used when MySQL is detected somehow, the
existing systems should
continue working with datetime.

>> I think this is the right way to go, as at least at the developer
>> level the behavior of that column will be the same as for postgresql,
>> as long as the SQLAlchemy APIs are used.
>
> OK, so there is no change to postgres column type involved here?
> That's great news!

Well, it should be transparent as long as we figure out how to create
a different underlying table
when MySQL is used - we need to use the decimal-backed column type in
that case. So for any
database except MySQL we'd use the normal SQLAlchemy datetime type,
and in MySQL we'd
use the special type I created. But these should behave in the same
way to anyone doing queries through MySQL, as in the Python world
they'll work with datetime objects.

Regards,

Martijn