Re: Failure to coerce unknown type to specific type

On Wed, Apr 29, 2015 at 6:37 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> We should, in fact, fail that to begin with.  Unknown-type columns are
>>> a spectactularly horrid idea.
>
>> I agree.  So why don't we throw an error when someone tries to create one?
>
> We should IMO, but there's been push-back about backwards compatibility
> when this has been proposed in the past.

I do think that there are probably people who have got cruft lying
around in their database where they've accidentally created views or
tables with unknown-type columns.  They are unlikely to be actually
used, but they may exist.  If we want to ease the
backward-compatibility pain, maybe we could map unknown -> text, so
that the upgrade still works but changes the column type under the
hood.  Or we can just break it.  But we should do something.

--
Robert Haas
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