From: Tom Lane <tgl@sss.pgh.pa.us>
To: marcus@cockroachlabs.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17371: Immutable INTERVAL to TEXT cast can cause incorrect
 query results
In-reply-to: <17371-8f57e6e9ca5e35bf@postgresql.org>
References: <17371-8f57e6e9ca5e35bf@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Wed, 19 Jan 2022 21:06:41 +0000"
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Date: Wed, 19 Jan 2022 16:42:44 -0500
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PG Bug reporting form <noreply@postgresql.org> writes:
> I believe casts from INTERVAL to TEXT (and other string-like types such as
> CHAR, NAME, VARCHAR, and "char") should have a volatility of stable, not
> immutable, because the results of these casts depend on IntervalStyle.

Ugh, right, interval_out is marked immutable and should not be.

The cost/benefit of trying to change this in released branches doesn't
seem attractive, but we can fix it for v15 and up.

(Oddly, interval_in is already correctly marked as STABLE.  I'm not
sure how it got to be that way with nobody noticing the mistake
for interval_out.)

Thanks for the report!

			regards, tom lane