From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter@eisentraut.org>
Cc: pgsql-bugs <pgsql-bugs@postgresql.org>
Subject: Re: CREATE CAST allows creation of binary-coercible cast to range over domain
Date: Tue, 20 Aug 2024 10:46:15 -0400
Message-ID: <1537781.1724165175@sss.pgh.pa.us> (raw)
In-Reply-To: <076968e1-0852-40a9-bc0b-117cd3f0e43c@eisentraut.org>
References: <076968e1-0852-40a9-bc0b-117cd3f0e43c@eisentraut.org>
Peter Eisentraut <peter@eisentraut.org> writes:
> CREATE CAST disallows creating a binary-coercible cast to a domain
> (because that would bypass checking the domain constraints). But it
> allows it if the domain is wrapped inside a range type:
> ...
> This particular case seems straightforward to fix, but maybe there are
> also cases with more nesting to consider.
I think it's an oversight that we allow binary-coercible casts
involving range types at all. There are no other nesting cases to
worry about, because CreateCast already rejects binary-coercible casts
applied to composites and arrays, explaining
* We know that composite, enum and array types are never binary-
* compatible with each other. They all have OIDs embedded in them.
But range types also embed their own OID, so I don't see why that
concern doesn't apply to them.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, peter@eisentraut.org
Subject: Re: CREATE CAST allows creation of binary-coercible cast to range over domain
In-Reply-To: <1537781.1724165175@sss.pgh.pa.us>
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