Re: Bug #513: union all changes char(3) column definition

> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> > Tom Lane writes:
> >> CREATE TABLE AS cannot be expected to be able to extract a suitable
> >> typmod from complex expressions.
>
> > I don't think that would be entirely unreasonable.
>
> Well, it might not be completely impossible, but I think it's well on
> the far side of unreasonable. For *every operator* that produces a
> result of any of the typmod-using types, we'd have to maintain an
> auxiliary bit of code that can predict the result typmod. That's
> a lot of code, and when you start considering user-defined functions
> it gets worse. And all for what? Not to do anything useful, but only
> to *eliminate* functionality. Perhaps char without typmod is
> unnecessary (since it reduces to text), but numeric without typmod seems
> highly useful to me.
>
> Strikes me as a very large amount of work to go in the wrong
> direction...

Added to TODO:

* CREATE TABLE AS can not determine column lengths from expressions

Seems it should be documented. Do we throw an error in these cases?

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