how can i mark date function like iscachable

erobles wrote:
> Hello there!
>
> i tried to create an functional index like this:
>
> create index estdistfecha on estadist (date(fecha));
>
>
> but only get the next message:
> ERROR: DefineIndex: index function must be marked iscachable.
>
> So, How can i mark the date function iscachable ? :-)
>
> i hope your anwsers, anyway thanks to read this !
>
>
>