Re: ALTER TYPE 2: skip already-provable no-work rewrites

On Sat, Feb 12, 2011 at 10:45 AM, Noah Misch <noah(at)leadboat(dot)com> wrote:
> That said, I've tried both constructions, and I marginally prefer the end result
> with AlteredTableInfo.verify.  I've inlined ATColumnChangeRequiresRewrite into
> ATPrepAlterColumnType; it would need to either pass back two bools or take an
> AlteredTableInfo arg to mutate, so this seemed cleaner.

I think I like the idea of passing it the AlteredTableInfo.

> I've omitted the
> assertion that my previous version added to ATRewriteTable; it was helpful for
> other scan-only type changes, but it's excessive for domains alone.  Otherwise,
> the differences are cosmetic.

So in the case of a constrained domain, it looks like we're going to
evaluate the changed columns, but if no error is thrown, we're going
to assume they match the original ones and throw out the data? Yikes.
I didn't like that Assert much, but maybe we need it, because this is
scary.

--
Robert Haas
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