Fixed the bug mdev-7791.

When an IN subquery predicate was converted to a semi-join that were
materialized and the result of the materialization happened to be
the last in the execution plan then any conjunctive condition with RAND()
turned out to be lost.

Fixed by attaching this condition to the last top base table.

1 files changed, 13 insertions, 5 deletions

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 09e6ece7807..bad57aeac87 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -8761,12 +8761,20 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
     /*
       Step #2: Extract WHERE/ON parts
     */
+    uint i;
+    for (i= join->top_join_tab_count - 1; i >= join->const_tables; i--)
+    {
+      if (!join->join_tab[i].bush_children)
+        break;
+    }
+    uint last_top_base_tab_idx= i;
+
     table_map save_used_tables= 0;
     used_tables=((select->const_tables=join->const_table_map) |
 		 OUTER_REF_TABLE_BIT | RAND_TABLE_BIT);
     JOIN_TAB *tab;
     table_map current_map;
-    uint i= join->const_tables;
+    i= join->const_tables;
     for (tab= first_depth_first_tab(join); tab;
          tab= next_depth_first_tab(join, tab), i++)
     {
@@ -8804,7 +8812,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
 	Following force including random expression in last table condition.
 	It solve problem with select like SELECT * FROM t1 WHERE rand() > 0.5
       */
-      if (tab == join->join_tab + join->top_join_tab_count - 1)
+      if (tab == join->join_tab + last_top_base_tab_idx)
         current_map|= RAND_TABLE_BIT;
       used_tables|=current_map;
 
@@ -8843,10 +8851,10 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
           save_used_tables= 0;
         }
         else
-         {
-	  tmp= make_cond_for_table(thd, cond, used_tables, current_map, i,
+        {
+          tmp= make_cond_for_table(thd, cond, used_tables, current_map, i,
                                    FALSE, FALSE);
-         }
+        }
         /* Add conditions added by add_not_null_conds(). */
         if (tab->select_cond)
           add_cond_and_fix(thd, &tmp, tab->select_cond);