=== modified file 'sql/sql_select.cc'
--- sql/sql_select.cc	2010-04-21 12:51:53 +0000
+++ sql/sql_select.cc	2010-04-26 16:08:25 +0000
@@ -283,6 +283,11 @@
 Item_equal *find_item_equal(COND_EQUAL *cond_equal, Field *field,
                             bool *inherited_fl);
 
+#ifndef DBUG_OFF
+const double ARTIFICIAL_LOW_COST= 1e-20;
+const double ARTIFICIAL_HIGH_COST= 1/ARTIFICIAL_LOW_COST;
+#endif
+
 
 /**
   This handles SELECT with and without UNION.
@@ -7682,6 +7687,24 @@
       advance_sj_state(join, remaining_tables, s, idx, &current_record_count,
                        &current_read_time, &loose_scan_pos);
 
+      /* This prefers a plan where tables are listed in alphabetical order */
+      DBUG_EXECUTE_IF("optimizer_force_alphab_sorted_plan",
+                      {
+                        uint i= 1;
+                        while (i < (idx + 1) &&
+                               (strcmp(join->positions[i-1].table->table->alias,
+                                       join->positions[i].table->table->alias)
+                                == -1))
+                          i++;
+                        if (i == (idx + 1))
+                        {
+                          DBUG_PRINT("info", ("found alphabetically sorted"
+                                              " plan with %u tables", idx + 1));
+                          current_read_time= current_record_count=
+                            ARTIFICIAL_LOW_COST; // prefer this plan
+                        }
+                      }
+                      );
       /* Expand only partial plans with lower cost than the best QEP so far */
       if ((current_read_time +
            current_record_count / (double) TIME_FOR_COMPARE) >= join->best_read)
@@ -13718,6 +13741,13 @@
                                one_lookup_cost;
       dups_cost += write_cost + full_lookup_cost;
       
+      DBUG_EXECUTE_IF("optimizer_avoid_dups_weedout",
+                      {
+                        /* This gives a high cost to this strategy: */
+                        dups_cost= prefix_rec_count= ARTIFICIAL_HIGH_COST;
+                        sj_outer_fanout= 1;
+                      }
+                      );
       /*
         Use the strategy if 
          * it is cheaper then what we've had, or