Fix ordering of GRANT commands in pg_dump for database creation

This uses a method similar to 68a7c24f, which guarantees that GRANT
commands using the WITH GRANT OPTION are dumped in a way so as cascading
dependencies are respected.  As databases do not have support for
initial privileges via pg_init_privs, we need to repeat again the same
ACL reordering method.

ACL for databases have been moved from pg_dumpall to pg_dump in v11, so
this impacts pg_dump for v11 and above, and pg_dumpall for v9.6 and
v10.

Discussion: https://postgr.es/m/15788-4e18847520ebcc75@postgresql.org
Author: Nathan Bossart
Reviewed-by: Haribabu Kommi
Backpatch-through: 9.6

src/bin/pg_dump/pg_dump.c

@@ -2664,20 +2664,41 @@ dumpDatabase(Archive *fout)
 
 	pg_log_info("saving database definition");
 
-	/* Fetch the database-level properties for this database */
+	/*
+	 * Fetch the database-level properties for this database.
+	 *
+	 * The order in which privileges are in the ACL string (the order they
+	 * have been GRANT'd in, which the backend maintains) must be preserved to
+	 * ensure that GRANTs WITH GRANT OPTION and subsequent GRANTs based on
+	 * those are dumped in the correct order.  Note that initial privileges
+	 * (pg_init_privs) are not supported on databases, so this logic cannot
+	 * make use of buildACLQueries().
+	 */
 	if (fout->remoteVersion >= 90600)
 	{
 		appendPQExpBuffer(dbQry, "SELECT tableoid, oid, datname, "
 						  "(%s datdba) AS dba, "
 						  "pg_encoding_to_char(encoding) AS encoding, "
 						  "datcollate, datctype, datfrozenxid, datminmxid, "
-						  "(SELECT array_agg(acl ORDER BY acl::text COLLATE \"C\") FROM ( "
-						  "  SELECT unnest(coalesce(datacl,acldefault('d',datdba))) AS acl "
-						  "  EXCEPT SELECT unnest(acldefault('d',datdba))) as datacls)"
+						  "(SELECT array_agg(acl ORDER BY row_n) FROM "
+						  "  (SELECT acl, row_n FROM "
+						  "     unnest(coalesce(datacl,acldefault('d',datdba))) "
+						  "     WITH ORDINALITY AS perm(acl,row_n) "
+						  "   WHERE NOT EXISTS ( "
+						  "     SELECT 1 "
+						  "     FROM unnest(acldefault('d',datdba)) "
+						  "       AS init(init_acl) "
+						  "     WHERE acl = init_acl)) AS datacls) "
 						  " AS datacl, "
-						  "(SELECT array_agg(acl ORDER BY acl::text COLLATE \"C\") FROM ( "
-						  "  SELECT unnest(acldefault('d',datdba)) AS acl "
-						  "  EXCEPT SELECT unnest(coalesce(datacl,acldefault('d',datdba)))) as rdatacls)"
+						  "(SELECT array_agg(acl ORDER BY row_n) FROM "
+						  "  (SELECT acl, row_n FROM "
+						  "     unnest(acldefault('d',datdba)) "
+						  "     WITH ORDINALITY AS initp(acl,row_n) "
+						  "   WHERE NOT EXISTS ( "
+						  "     SELECT 1 "
+						  "     FROM unnest(coalesce(datacl,acldefault('d',datdba))) "
+						  "       AS permp(orig_acl) "
+						  "     WHERE acl = orig_acl)) AS rdatacls) "
 						  " AS rdatacl, "
 						  "datistemplate, datconnlimit, "
 						  "(SELECT spcname FROM pg_tablespace t WHERE t.oid = dattablespace) AS tablespace, "