From: Tom Lane <tgl@sss.pgh.pa.us>
To: Christoph Berg <myon@debian.org>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: pgsql: Improve default and empty privilege outputs in psql.
In-reply-to: <3361177.1727195279@sss.pgh.pa.us>
References: <E1r2dkc-005J8F-Qc@gemulon.postgresql.org> <ZvLXYglRS6hMMhtr@msg.df7cb.de> <3361177.1727195279@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Tue, 24 Sep 2024 12:27:59 -0400"
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Date: Tue, 24 Sep 2024 13:57:28 -0400
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I wrote:
> Yes, that's the expectation.  I'm sure we can think of a more
> backwards-compatible way to test for empty datacl, though.

Looks like the attached should be sufficient.  As penance, I tried
all the commands in describe.c against 9.2 (or the oldest supported
server version), and none of them fail now.

			regards, tom lane


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Content-Description: fix-ACL-printing-for-old-servers.patch

diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index faabecbc76..6a36c91083 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -6678,7 +6678,7 @@ printACLColumn(PQExpBuffer buf, const char *colname)
 {
 	appendPQExpBuffer(buf,
 					  "CASE"
-					  " WHEN pg_catalog.cardinality(%s) = 0 THEN '%s'"
+					  " WHEN pg_catalog.array_length(%s, 1) = 0 THEN '%s'"
 					  " ELSE pg_catalog.array_to_string(%s, E'\\n')"
 					  " END AS \"%s\"",
 					  colname, gettext_noop("(none)"),

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