From: Tom Lane <tgl@sss.pgh.pa.us>
To: adamkpickering@gmail.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19543: ALTER RULE ... RENAME accepts reserved name "_RETURN"
 for a non-view rule; breaks a restored dump
In-reply-to: <19543-461228e77f3b32fc@postgresql.org>
References: <19543-461228e77f3b32fc@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Fri, 03 Jul 2026 23:26:57 -0000"
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Date: Sat, 04 Jul 2026 10:37:37 -0400
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PG Bug reporting form <noreply@postgresql.org> writes:
> CREATE RULE rejects the name _RETURN for a rule that is not an ON SELECT
> rule. ALTER RULE ... RENAME does not: an existing ON UPDATE/INSERT/DELETE
> rule on an ordinary table can be renamed to _RETURN and the server accepts
> it.

Good catch, will fix.

While we're here, I'm tempted to discard the obsolete logic in
CREATE RULE's implementation of a related check:

        /*
         * ... and finally the rule must be named _RETURN.
         */
        if (strcmp(rulename, ViewSelectRuleName) != 0)
        {
            /*
             * In versions before 7.3, the expected name was _RETviewname. For
             * backwards compatibility with old pg_dump output, accept that
             * and silently change it to _RETURN.  Since this is just a quick
             * backwards-compatibility hack, limit the number of characters
             * checked to a few less than NAMEDATALEN; this saves having to
             * worry about where a multibyte character might have gotten
             * truncated.
             */
            if (strncmp(rulename, "_RET", 4) != 0 ||
                strncmp(rulename + 4, RelationGetRelationName(event_relation),
                        NAMEDATALEN - 4 - 4) != 0)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("view rule for \"%s\" must be named \"%s\"",
                                RelationGetRelationName(event_relation),
                                ViewSelectRuleName)));

We discarded compatibility with pre-7.3 dump files some time ago
(notably in e58a59975 and adjacent commits), but this small detail
wasn't noticed at the time.

			regards, tom lane