Re: hstore improvements?

On Mar 13, 2009, at 2:26 PM, Andrew Gierth wrote:

> David> Is a more Perlish syntax out of the question?
>
> Yes. Sorry.
>
> David> SELECT ('a=>1,b=>2,c=>3'::hstore)['a', 'b'];
> David> -- returns '{1,2}'
>
> That would require integrating hstore into core - array subscripting
> isn't a user-definable operation.
>
> David> select ('a=>1,b=>2,c=>3'::hstore){'a','b'};
> David> -- returns 'a=>1,b=>2'
>
> And that would require changing the parser...

How functionS, then?

SELECT slice(('a=>1,b=>2,c=>3'::hstore), ARRAY['a', 'b']);
-- returns '{1,2}'

SELECT hslice(('a=>1,b=>2,c=>3'::hstore), ARRAY['a','b']);
-- returns 'a=>1,b=>2'

Better names welcome, of course. But there isn't even a slice
interface for array, is there?

SELECT slice(ARRAY[ 'a', 'b', 'c' ], ARRAY[1, 3]);
-- returns '{a,c}'

Best,

David