You could convert your timestamp into an integer (number of seconds since
the epoch).
Also, under certain conditions, you can cheat and use a sequence instead
of a timestamp.
>
> Hi,
> I need an index on a postgis-point and a timestamp.
> I'm using an GiST index on the geometry. But the creation of an GiST
> index
> on geometry and timestamp seems to be impossible, because GiST doesn't
> support Timestamps.
> Is there a possibility to solve my problem?
>
> Greetings
> Jens
>