Re: ALTER TYPE 3: add facility to identify further no-work cases

Noah Misch <noah@leadboat.com> writes:
> text -> xml

BTW, that reminds me of something that I think was mentioned way back
when, but absolutely fails to fit into any of the frameworks discussed
here: the mere fact that a type is binary-compatible (with or without
checking) doesn't make it compatible enough to not have to recreate
indexes.  Where and how are we going to have a wart to determine if
that's necessary?  And if the answer is "rebuild indexes whenever the
data type changes", isn't that a further big dent in the argument that
it's worth avoiding a table rewrite?  A text->xml replacement is going
to be far from cheap anyway.
        regards, tom lane