Re: Identifying no-op length coercions

On Mon, May 23, 2011 at 1:53 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Maybe.  But casts would be the least of our concerns if we were trying
> to change the column type.  Changing typmod doesn't affect the set of
> operations that could be applied to a column, whereas changing type
> surely does.

OK, this is the crucial point I was missing.  Sorry for being a bit
fuzzy-headed about this.

My mental model of our type system, or of what a type system ought to
do, just doesn't match the type system we've got.

So let's do it the way you proposed.

-- 
Robert Haas
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