On Wed, Jan 7, 2026 at 11:57 PM Laurenz Albe <[email protected]>
wrote:
> Yes, using "varchar" is definitely part of why it is so odd.
> There is no equality operator for "varchar", so you need an (implicit)
> cast to "text".
>
Got it. That seems like a possible reason to prefer text over varchar.
> That implicit cast is made explicit when the parsed binary form of the
> constraint expression is
> reverse engineered to a string during "pg_dump".
>
Makes sense.
> I'd say that the change you mention "just happened", but you can never
> rely on these expressions
> being rendered in a fixed way - this can change any time.
>
That seems reasonable. What mostly seemed unexpected was that the parsed
expression changed the second time. i.e. original expression -> rewritten
expression with explicit type casting -> rewritten expression with (even
more!) explicit type casting.
> But perhaps it is good enoulh if you define the constraint by casting to
> "text"
> early: CHECK (val::text IN ('a','b','c'))
>
Sounds good, I may try that. Thanks!
> > This communication and any attachments may contain confidential
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>
> Got it, I won't forward your mail... err...
>
Heh, yes... sorry about that. I can't control how that message is included
from this email address. Rest assured, you and everyone else here are the
intended recipients :-)
Regards,
Stuart
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