Re: Error trying to create a functional index. - Mailing list pgsql-sql

CoL wrote:

> 
> sure it is, but date_trunc takes this, so what is the way to create a 
> date_trunc part or any date function index on a timestamp?
> 
> Or it's not possible?


I would tend to believe it is not directly possible. But maybe with a 
custom function:

(pseudocode, check whether Day is a reserved word)
CREATE FUNCTION Day(date) RETURNS varchar AS '
BEGIN  RETURN Cast(date_trunc('day', $1) AS varchar);
END;
' LANGUAGE 'SQL';

CREATE INDEX eventdateindex ON event (Day(eventstamp));

SELECT Day(eventstamp) FROM event;


Jochem