Re: Bytea binary compatible

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > OK, code backed out.  If the storage formats are the same, doesn't that
> > make them binary compatibile.
>
> No, because one allows nulls and the other doesn't.  If you disregard
> what are legal values and what aren't, then every pair of varlena
> datatypes we have could be called "binary compatible".
>
> More to the point, though, why *should* they be marked binary
> compatible?  I saw no compelling reason advanced for it, and I can see a
> couple of compelling reasons not to.  Every binary-compatible pairing is
> another hole in our type system, another opportunity for unexpected
> behavior.  We shouldn't add them on whims.  Especially we shouldn't add
> them for datatypes that aren't even of the same family.  bytea isn't for
> storage of textual data, and so it makes little sense to allow
> application of textual operations to it.

I have no idea why the user wanted it.  I suppose it was so he could
pass text/varchar to bytea and back again.  Seems he has to convert it,
which makes sense about the NULLs.

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