Re: Bug #620: create index ... (date_part('year', d)) fails

sszabo(at)bigpanda(dot)com

On Fri, 15 Mar 2002 pgsql-bugs(at)postgresql(dot)org wrote:

> Ernst Molitor (molitor(at)uni-bonn(dot)de) reports a bug with a severity of 3
> The lower the number the more severe it is.
>
> Short Description
> create index ... (date_part('year', d)) fails
>
> Long Description
> IMHO, creation of an index on a part of a date field should work,
> but it fails due to the definition of "create index ..." in gram.y.
>
> Maybe I'm wrong, but I feel that for large tables which will have to
> be analyzed per year, an index of this kind could be an advantage.

You need to make a function that is marked iscachable that returns
date_part('year', <argument>) and use that. IIRC, functional indices
require that all of the arguments be column references.