Re: slow IN() clause for many cases

On Fri, Oct 14, 2005 at 07:09:17PM -0400, Tom Lane wrote:
> I wrote:
> > I'm thinking that IN should be
> > converted to a ScalarArrayOpExpr, ie
> > x = ANY (ARRAY[val1,val2,val3,val4,...])
> Actually, there is one little thing in the way of doing this: it'll
> fail if any of the IN-list elements are NULL, because we have not got
> support for arrays with null elements. So we'd have to fix that first.

Hey Tom.

Obviously your area of expertise, so please tell me where I'm wrong -

But doesn't "x IN (NULL)" already fail to ever match, similar to "x
= NULL"? (Assuming that compatibility switch isn't enabled)

So, I'd hope people weren't using such an expression? :-) Or is that
not good enough? What does NULL::text[] turn into? An empty string? Is
that the danger? It might match against an empty string?

Cheers,
mark

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