Fixed LP BUG#615760: Check on double cache assignment added into the transformation methods.

Cache parameters print added in EXPLAIN EXTENDED output.

mysql-test/r/compare.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/group_by.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect3.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect3_jcl6.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect4.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect_cache.result:
  Added test suite for LP BUG#615760
mysql-test/r/subselect_mat.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect_no_mat.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect_no_opts.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect_no_semijoin.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect_sj.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/r/subselect_sj_jcl6.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/suite/pbxt/r/subselect.result:
  Cache parameters print added in EXPLAIN EXTENDED output.
mysql-test/t/subselect_cache.test:
  Cache parameters print added in EXPLAIN EXTENDED output.
sql/item.cc:
  Item::set_expr_cache result fixed according to its description.
  
  Cache parameters print added in EXPLAIN EXTENDED output.
sql/item.h:
  Cache parameters print added in EXPLAIN EXTENDED output.
sql/item_cmpfunc.cc:
  Check on double cache assignment added into the transformation methods.
sql/item_cmpfunc.h:
  Check on double cache assignment added into the transformation methods.
sql/item_subselect.cc:
  Check on double cache assignment added into the transformation methods.
sql/item_subselect.h:
  Check on double cache assignment added into the transformation methods.
sql/sql_expression_cache.cc:
  Cache parameters print added.
sql/sql_expression_cache.h:
  Cache parameters print added.
sql/sql_select.cc:
  Removed unused method (now it is impossible to make double transformation with the cache).
sql/sql_select.h:
  Removed unused method.

10 files changed, 79 insertions, 86 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 1976b6f5015..8f393eca79b 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -567,10 +567,10 @@ Item* Item::set_expr_cache(THD *thd, List<Item *> &depends_on)
       !wrapper->fix_fields(thd, (Item**)&wrapper))
   {
     if (wrapper->set_cache(thd, depends_on))
-      DBUG_RETURN(this);
+      DBUG_RETURN(NULL);
     DBUG_RETURN(wrapper);
   }
-  DBUG_RETURN(this);
+  DBUG_RETURN(NULL);
 }
 
 
@@ -6635,6 +6635,19 @@ Item_cache_wrapper::Item_cache_wrapper(Item *item_arg)
 }
 
 
+void Item_cache_wrapper::print(String *str, enum_query_type query_type)
+{
+  str->append(func_name());
+  if (expr_cache)
+    expr_cache->print(str, query_type);
+  else
+    str->append(STRING_WITH_LEN("<<DISABLED>>"));
+  str->append('(');
+  orig_item->print(str, query_type);
+  str->append(')');
+}
+
+
 /**
   Prepare the expression cache wrapper (do nothing)
 
diff --git a/sql/item.h b/sql/item.h
index 4e26e526b7b..05e35e97e04 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -2628,13 +2628,7 @@ public:
 
   /* Following methods make this item transparent as much as possible */
 
-  virtual void print(String *str, enum_query_type query_type)
-  {
-    str->append(func_name());
-    str->append('(');
-    orig_item->print(str, query_type);
-    str->append(')');
-  }
+  virtual void print(String *str, enum_query_type query_type);
   virtual const char *full_name() const { return orig_item->full_name(); }
   virtual void make_field(Send_field *field) { orig_item->make_field(field); }
   bool eq(const Item *item, bool binary_cmp) const
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index d1ef5fb5264..6b075c2d4aa 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -1774,6 +1774,9 @@ Item *Item_in_optimizer::expr_cache_insert_transformer(uchar *thd_arg)
   DBUG_ENTER("Item_in_optimizer::expr_cache_insert_transformer");
   List<Item*> &depends_on= ((Item_subselect *)args[1])->depends_on;
 
+  if (expr_cache)
+    DBUG_RETURN(expr_cache);
+
   /* Add left expression to the list of the parameters of the subquery */
   if (args[0]->cols() == 1)
     depends_on.push_front((Item**)args);
@@ -1785,8 +1788,11 @@ Item *Item_in_optimizer::expr_cache_insert_transformer(uchar *thd_arg)
     }
   }
 
-  if (args[1]->expr_cache_is_needed(thd))
-    DBUG_RETURN(set_expr_cache(thd, depends_on));
+  if (args[1]->expr_cache_is_needed(thd) &&
+      (expr_cache= set_expr_cache(thd, depends_on)))
+    DBUG_RETURN(expr_cache);
+
+  depends_on.pop();
   DBUG_RETURN(this);
 }
 
@@ -1889,6 +1895,7 @@ void Item_in_optimizer::cleanup()
   Item_bool_func::cleanup();
   if (!save_cache)
     cache= 0;
+  expr_cache= 0;
   DBUG_VOID_RETURN;
 }
 
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 053a54349c2..2eb419738e3 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -242,6 +242,7 @@ class Item_in_optimizer: public Item_bool_func
 {
 protected:
   Item_cache *cache;
+  Item *expr_cache;
   bool save_cache;
   /* 
     Stores the value of "NULL IN (SELECT ...)" for uncorrelated subqueries:
@@ -252,7 +253,7 @@ protected:
   my_bool result_for_null_param;
 public:
   Item_in_optimizer(Item *a, Item_in_subselect *b):
-    Item_bool_func(a, my_reinterpret_cast(Item *)(b)), cache(0),
+    Item_bool_func(a, my_reinterpret_cast(Item *)(b)), cache(0), expr_cache(0),
     save_cache(0), result_for_null_param(UNKNOWN)
   {}
   bool fix_fields(THD *, Item **);
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 7f5f0fd51f1..814bf14bb3e 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -34,11 +34,10 @@
 
 Item_subselect::Item_subselect():
   Item_result_field(), value_assigned(0), thd(0), substitution(0),
-  engine(0), old_engine(0), used_tables_cache(0), have_to_be_excluded(0),
-  const_item_cache(1), 
-  inside_first_fix_fields(0), done_first_fix_fields(FALSE),
-  eliminated(FALSE), 
-  engine_changed(0), changed(0), is_correlated(FALSE)
+  expr_cache(0), engine(0), old_engine(0), used_tables_cache(0),
+  have_to_be_excluded(0), const_item_cache(1), inside_first_fix_fields(0),
+  done_first_fix_fields(FALSE), eliminated(FALSE), engine_changed(0),
+  changed(0), is_correlated(FALSE)
 {
   with_subselect= 1;
   reset();
@@ -121,6 +120,7 @@ void Item_subselect::cleanup()
   depends_on.empty();
   reset();
   value_assigned= 0;
+  expr_cache= 0;
   DBUG_VOID_RETURN;
 }
 
@@ -861,8 +861,12 @@ Item* Item_singlerow_subselect::expr_cache_insert_transformer(uchar *thd_arg)
   THD *thd= (THD*) thd_arg;
   DBUG_ENTER("Item_singlerow_subselect::expr_cache_insert_transformer");
 
-  if (expr_cache_is_needed(thd))
-    DBUG_RETURN(set_expr_cache(thd, depends_on));
+  if (expr_cache)
+    DBUG_RETURN(expr_cache);
+
+  if (expr_cache_is_needed(thd) &&
+      (expr_cache= set_expr_cache(thd, depends_on)))
+    DBUG_RETURN(expr_cache);
   DBUG_RETURN(this);
 }
 
@@ -1083,8 +1087,12 @@ Item* Item_exists_subselect::expr_cache_insert_transformer(uchar *thd_arg)
   THD *thd= (THD*) thd_arg;
   DBUG_ENTER("Item_exists_subselect::expr_cache_insert_transformer");
 
-  if (substype() == EXISTS_SUBS && expr_cache_is_needed(thd))
-    DBUG_RETURN(set_expr_cache(thd, depends_on));
+  if (expr_cache)
+    DBUG_RETURN(expr_cache);
+
+  if (substype() == EXISTS_SUBS && expr_cache_is_needed(thd) &&
+      (expr_cache= set_expr_cache(thd, depends_on)))
+    DBUG_RETURN(expr_cache);
   DBUG_RETURN(this);
 }
 
diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index 72f73d58867..3b0a9075a20 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -53,6 +53,7 @@ public:
   /* unit of subquery */
   st_select_lex_unit *unit;
 protected:
+  Item *expr_cache;
   /* engine that perform execution of subselect (single select or union) */
   subselect_engine *engine;
   /* old engine if engine was changed */
@@ -214,7 +215,8 @@ protected:
   Item_cache *value, **row;
 public:
   Item_singlerow_subselect(st_select_lex *select_lex);
-  Item_singlerow_subselect() :Item_subselect(), value(0), row (0) {}
+  Item_singlerow_subselect() :Item_subselect(), value(0), row (0)
+  {}
 
   void cleanup();
   subs_type substype() { return SINGLEROW_SUBS; }
diff --git a/sql/sql_expression_cache.cc b/sql/sql_expression_cache.cc
index 9596ca87bab..cbbafbd55c8 100644
--- a/sql/sql_expression_cache.cc
+++ b/sql/sql_expression_cache.cc
@@ -314,3 +314,21 @@ err:
   cache_table= NULL;
   DBUG_RETURN(TRUE);
 }
+
+
+void Expression_cache_tmptable::print(String *str, enum_query_type query_type)
+{
+  List_iterator<Item*> li(*list);
+  Item **item;
+  bool is_first= TRUE;
+
+  str->append('<');
+  while ((item= li++))
+  {
+    if (!is_first)
+      str->append(',');
+    (*item)->print(str, query_type);
+    is_first= FALSE;
+  }
+  str->append('>');
+}
diff --git a/sql/sql_expression_cache.h b/sql/sql_expression_cache.h
index bb5dc7a76a2..e931eca6091 100644
--- a/sql/sql_expression_cache.h
+++ b/sql/sql_expression_cache.h
@@ -32,6 +32,11 @@ public:
     into the expression cache
   */
   virtual my_bool put_value(Item *value)= 0;
+
+  /**
+    Print cache parameters
+  */
+  virtual void print(String *str, enum_query_type query_type)= 0;
 };
 
 struct st_table_ref;
@@ -51,6 +56,8 @@ public:
   virtual result check_value(Item **value);
   virtual my_bool put_value(Item *value);
 
+  void print(String *str, enum_query_type query_type);
+
 private:
   void init();
   bool make_equalities();
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 2638daf4e5c..09d8be97eb4 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -1517,63 +1517,6 @@ setup_subq_exit:
 
 
 /**
-  Transform given item with changing it in all_fields if it is needed.
-
-  @param expr            Reference on expression to transform
-  @param transformer     Transformer to apply to the expression
-
-  @details
-  The function transforms the expression expr and, if the top item of the
-  expression has changed, the function looks for the item in
-  JOIN::all_fields and replaces it with the result of transformation.
-*/
-
-void JOIN::transform_and_change_in_all_fields(Item** expr,
-                                              Item_transformer transformer)
-{
-  DBUG_ENTER("JOIN::transform_and_change_in_all_fields");
-  Item *new_item= (*expr)->transform(transformer,
-                                    (uchar*) thd);
-  if (new_item != (*expr))
-  {
-    List_iterator<Item> li(all_fields);
-    Item *it;
-
-    /*
-      Check if this item already has expression cache and if it has then use
-      that cache instead of the cache we have just created
-   */
-    while ((it= li++))
-    {
-      if (((*expr) == it->get_cached_item()))
-      {
-        /*
-          We have to forget about the created cache, but this situation is
-          really rare.
-        */
-        new_item->cleanup();
-        new_item= it;
-        DBUG_PRINT("info", ("Other cache found"));
-        break;
-      }
-    }
-
-    li.rewind();
-    while ((it= li++))
-    {
-      if (it == (*expr))
-      {
-        li.replace(new_item);
-        DBUG_PRINT("info", ("Cache Added"));
-      }
-    }
-    *expr= new_item;
-  }
-  DBUG_VOID_RETURN;
-}
-
-
-/**
   Setup expression caches for subqueries that need them
 
   @details
@@ -1633,7 +1576,7 @@ bool JOIN::setup_subquery_caches()
       select_lex->expr_cache_may_be_used[IN_GROUP_BY] ||
       select_lex->expr_cache_may_be_used[NO_MATTER])
   {
-    List_iterator<Item> li(fields_list);
+    List_iterator<Item> li(all_fields);
     Item *item;
     while ((item= li++))
     {
@@ -1646,16 +1589,18 @@ bool JOIN::setup_subquery_caches()
     }
     for (ORDER *group= group_list; group ; group= group->next)
     {
-      transform_and_change_in_all_fields(group->item,
-                                         &Item::expr_cache_insert_transformer);
+      *group->item=
+        (*group->item)->transform(&Item::expr_cache_insert_transformer,
+                                  (uchar*) thd);
     }
   }
   if (select_lex->expr_cache_may_be_used[NO_MATTER])
   {
     for (ORDER *ord= order; ord; ord= ord->next)
     {
-      transform_and_change_in_all_fields(ord->item,
-                                         &Item::expr_cache_insert_transformer);
+      *ord->item=
+        (*ord->item)->transform(&Item::expr_cache_insert_transformer,
+                                (uchar*) thd);
     }
   }
   DBUG_RETURN(FALSE);
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 2b7fc8fd47c..affa0fd3ed4 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -1742,8 +1742,6 @@ private:
   */
   bool implicit_grouping; 
   bool make_simple_join(JOIN *join, TABLE *tmp_table);
-  void transform_and_change_in_all_fields(Item** item,
-                                          Item_transformer transformer);
 };