Merge MWL#89 into 5.3 main.

1 files changed, 23 insertions, 0 deletions

diff --git a/sql/item.h b/sql/item.h
index d57155da9b1..f78f25bb9d2 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -491,6 +491,17 @@ typedef void (*Cond_traverser) (const Item *item, void *arg);
 class Item {
   Item(const Item &);			/* Prevent use of these */
   void operator=(Item &);
+  /**
+    The index in the JOIN::join_tab array of the JOIN_TAB this Item is attached
+    to. Items are attached (or 'pushed') to JOIN_TABs during optimization by the
+    make_cond_for_table procedure. During query execution, this item is
+    evaluated when the join loop reaches the corresponding JOIN_TAB.
+
+    If the value of join_tab_idx >= MAX_TABLES, this means that there is no
+    corresponding JOIN_TAB.
+  */
+  uint join_tab_idx;
+
 public:
   static void *operator new(size_t size) throw ()
   { return sql_alloc(size); }
@@ -950,6 +961,8 @@ public:
   virtual bool register_field_in_read_map(uchar *arg) { return 0; }
   virtual bool enumerate_field_refs_processor(uchar *arg) { return 0; }
   virtual bool mark_as_eliminated_processor(uchar *arg) { return 0; }
+  virtual bool eliminate_subselect_processor(uchar *arg) { return 0; }
+  virtual bool set_fake_select_as_master_processor(uchar *arg) { return 0; }
 
   /* To call bool function for all arguments */
   struct bool_func_call_args
@@ -1179,6 +1192,16 @@ public:
 
   Item* set_expr_cache(THD *thd, List<Item*> &depends_on);
   virtual Item *get_cached_item() { return NULL; }
+  /**
+    Set the join tab index to the minimal (left-most) JOIN_TAB to which this
+    Item is attached.
+  */
+  virtual void set_join_tab_idx(uint join_tab_idx_arg)
+  {
+    if (join_tab_idx_arg < join_tab_idx)
+      join_tab_idx= join_tab_idx_arg;
+  }
+  virtual uint get_join_tab_idx() { return join_tab_idx; }
 };