Re: array constructor can't construct empty array

> I can
>   select foo('{}'::int4[]) -- ok
>   select foo('{}')         -- ok too
> but
>   select foo(array[])      -- syntax error, 
> 
> my function can by like

Correct -- you cannot use the ARRAY constructor empty. If you need an 
empty array, use '{}'. Search the archives for previous discussions on 
this topic during the June/July timeframe. This might change for 7.5, 
but don't count on it (at least not yet).

Joe