Automerge.

mysql-test/r/group_min_max.result

@@ -2480,4 +2480,15 @@ SELECT a, MAX(b) FROM t WHERE b > 0 AND b < 2 GROUP BY a;
 a	MAX(b)
 2	1
 DROP TABLE t;
+#
+# Bug #48472: Loose index scan inappropriately chosen for some WHERE
+#             conditions
+# 
+CREATE TABLE t (a INT, b INT, INDEX (a,b));
+INSERT INTO t VALUES (2,0), (2,0), (2,1), (2,1);
+INSERT INTO t SELECT * FROM t;
+SELECT a, MAX(b) FROM t WHERE 0=b+0 GROUP BY a;
+a	MAX(b)
+2	0
+DROP TABLE t;
 End of 5.0 tests

mysql-test/t/group_min_max.test

@@ -991,5 +991,17 @@ SELECT a, MAX(b) FROM t WHERE b > 0 AND b < 2 GROUP BY a;
 
 DROP TABLE t;
 
+--echo #
+--echo # Bug #48472: Loose index scan inappropriately chosen for some WHERE
+--echo #             conditions
+--echo # 
+
+CREATE TABLE t (a INT, b INT, INDEX (a,b));
+INSERT INTO t VALUES (2,0), (2,0), (2,1), (2,1);
+INSERT INTO t SELECT * FROM t;                                   
+
+SELECT a, MAX(b) FROM t WHERE 0=b+0 GROUP BY a;
+
+DROP TABLE t;
 
 --echo End of 5.0 tests

sql/opt_range.cc

@@ -8244,7 +8244,11 @@ check_group_min_max_predicates(COND *cond, Item_field *min_max_arg_item,
     }
     else if (cur_arg->const_item())
     {
-      DBUG_RETURN(TRUE);
+      /*
+        For predicates of the form "const OP expr" we also have to check 'expr'
+        to make a decision.
+      */
+      continue;
     }
     else
       DBUG_RETURN(FALSE);