Re: View prevents index

> Christopher Masto <chris+pg-general@netmonger.net> writes:
> > I guess maybe I'm expecting too much magic optimization.
>
> You're expecting the system to transform
>
>     (SELECT foo UNION SELECT bar) WHERE condition
>
> into
>
>     (SELECT foo WHERE condition) UNION (SELECT bar WHERE condition)
>
> It's not immediately obvious to me that these are equivalent, or
> perhaps I should say it's not clear under what conditions is the
> transformation legitimate.

Could you tell me in what cases two of above are not equivalent? Or
any specification in the standard that refers to this kind of
transformation for views?
--
Tatsuo Ishii