Fix psql describe commands' handling of ACL columns for old servers.

Commit d1379ebf4 carelessly broke printACLColumn for pre-9.4 servers,
by using the cardinality() function which we introduced in 9.4.
We expect psql's describe-related commands to work back to 9.2, so
this is bad.  Use the longstanding array_length() function instead.

Per report from Christoph Berg.  Back-patch to v17.

Discussion: https://postgr.es/m/ZvLXYglRS6hMMhtr@msg.df7cb.de

diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index faabecbc76f06cc16caf8fdc812c47877d959de7..6a36c9108332b6b000d9e298e383fc2e96dda283 100644 (file)
--- 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)"),