In version 1.3.172, a performance regression was introduced when fixing the…

In version 1.3.172, a performance regression was introduced when fixing the issue 389 (when there is a multi-column primary key, H2 does not seem to always pick the right index). This was related to boosting an index that matches the "order by" column list (the wrong index was used in some cases).

h2/src/main/org/h2/command/dml/Select.java

@@ -1130,7 +1130,10 @@ public class Select extends Query {
         }
         if (orderList != null) {
             for (SelectOrderBy order : orderList) {
-                order.expression.mapColumns(resolver, level);
+                Expression e = order.expression;
+                if (e != null) {
+                    e.mapColumns(resolver, level);
+                }
             }
         }
     }