MWL#89 Addressing Sergey's review comments - Part 1.

Address the 'trivial' part of Sergey's review of MWL#89.

sql/item.h

@@ -536,7 +536,7 @@ public:
              SUBSELECT_ITEM, ROW_ITEM, CACHE_ITEM, TYPE_HOLDER,
              PARAM_ITEM, TRIGGER_FIELD_ITEM, DECIMAL_ITEM,
              XPATH_NODESET, XPATH_NODESET_CMP,
-             VIEW_FIXER_ITEM, EXPR_CACHE_ITEM, UNKNOWN_ITEM};
+             VIEW_FIXER_ITEM, EXPR_CACHE_ITEM};
 
   enum cond_result { COND_UNDEF,COND_OK,COND_TRUE,COND_FALSE };
 

sql/item_subselect.cc

@@ -1766,7 +1766,7 @@ Item_in_subselect::create_single_in_to_exists_cond(JOIN * join,
         *having_item= new_having;
       }
       else
-        DBUG_ASSERT(FALSE);
+        DBUG_ASSERT(false);
     }
   }
 

sql/opt_subselect.cc

@@ -3640,7 +3640,7 @@ static void remove_subq_pushed_predicates(JOIN *join, Item **where)
 
 
 /**
-  Optimize all subqueries of a query that have were flattened into a semijoin.
+  Optimize all subqueries of a query that were not flattened into a semijoin.
 
   @details
   Optimize all immediate children subqueries of a query.
@@ -3699,7 +3699,7 @@ bool JOIN::optimize_unflattened_subqueries()
 
 bool JOIN::choose_subquery_plan(table_map join_tables)
 {
-  Query_plan_state save_qep; /* The original QEP of the subquery. */
+  Join_plan_state save_qep; /* The original QEP of the subquery. */
   enum_reopt_result reopt_result= REOPT_NONE;
   Item_in_subselect *in_subs;
 

sql/sql_select.cc

@@ -959,7 +959,8 @@ JOIN::optimize()
     */
     if ((res=opt_sum_query(thd, select_lex->leaf_tables, all_fields, conds)))
     {
-      if (res == HA_ERR_KEY_NOT_FOUND || res < 0)
+      DBUG_ASSERT(res >= 0);
+      if (res == HA_ERR_KEY_NOT_FOUND)
       {
         DBUG_PRINT("info",("No matching min/max row"));
 	zero_result_cause= "No matching min/max row";
@@ -20528,7 +20529,7 @@ void JOIN::set_allowed_join_cache_types()
   @param save_to  The object into which the current query plan state is saved
 */
 
-void JOIN::save_query_plan(Query_plan_state *save_to)
+void JOIN::save_query_plan(Join_plan_state *save_to)
 {
   if (keyuse.elements)
   {
@@ -20558,7 +20559,7 @@ void JOIN::save_query_plan(Query_plan_state *save_to)
   @param The object from which the current query plan state is restored.
 */
 
-void JOIN::restore_query_plan(Query_plan_state *restore_from)
+void JOIN::restore_query_plan(Join_plan_state *restore_from)
 {
   if (restore_from->keyuse.elements)
   {
@@ -20607,7 +20608,7 @@ void JOIN::restore_query_plan(Query_plan_state *restore_from)
 
 JOIN::enum_reopt_result
 JOIN::reoptimize(Item *added_where, table_map join_tables,
-                 Query_plan_state *save_to)
+                 Join_plan_state *save_to)
 {
   DYNAMIC_ARRAY added_keyuse;
   SARGABLE_PARAM *sargables= 0; /* Used only as a dummy parameter. */

sql/sql_select.h

@@ -611,9 +611,10 @@ protected:
 
   /**
     The subset of the state of a JOIN that represents an optimized query
-    execution plan. Allows saving/restoring different plans for the same query.
+    execution plan. Allows saving/restoring different JOIN plans for the same
+    query.
   */
-  class Query_plan_state {
+  class Join_plan_state {
   public:
     DYNAMIC_ARRAY keyuse; /* Copy of the JOIN::keyuse array. */
     POSITION best_positions[MAX_TABLES+1]; /* Copy of JOIN::best_positions */
@@ -622,13 +623,13 @@ protected:
     /* Copies of JOIN_TAB::checked_keys for each JOIN_TAB. */
     key_map join_tab_checked_keys[MAX_TABLES];
   public:
-    Query_plan_state()
+    Join_plan_state()
     {   
       keyuse.elements= 0;
       keyuse.buffer= NULL;
     }
-    Query_plan_state(JOIN *join);
-    ~Query_plan_state()
+    Join_plan_state(JOIN *join);
+    ~Join_plan_state()
     {
       delete_dynamic(&keyuse);
     }
@@ -644,9 +645,9 @@ protected:
 
   /* Support for plan reoptimization with rewritten conditions. */
   enum_reopt_result reoptimize(Item *added_where, table_map join_tables,
-                               Query_plan_state *save_to);
-  void save_query_plan(Query_plan_state *save_to);
-  void restore_query_plan(Query_plan_state *restore_from);
+                               Join_plan_state *save_to);
+  void save_query_plan(Join_plan_state *save_to);
+  void restore_query_plan(Join_plan_state *restore_from);
   /* Choose a subquery plan for a table-less subquery. */
   bool choose_tableless_subquery_plan();
 
@@ -748,7 +749,7 @@ public:
   */
   double   best_read;
   /*
-    Estimated result rows (fanout) of the whole query. If this is a subquery
+    Estimated result rows (fanout) of the join operation. If this is a subquery
     that is reexecuted multiple times, this value includes the estiamted # of
     reexecutions. This value is equal to the multiplication of all
     join->positions[i].records_read of a JOIN.