MWL#90: subquery optimizations

- Remove redundant changes againist 5.3-main

sql/item_subselect.cc

@@ -3587,7 +3587,7 @@ subselect_hash_sj_engine::get_strategy_using_schema()
         bitmap_set_bit(&partial_match_key_parts, i);
         ++count_partial_match_columns;
       }
-    };
+    }
   }
 
   /* If no column contains NULLs use regular hash index lookups. */
@@ -3787,7 +3787,8 @@ bitmap_init_memroot(MY_BITMAP *map, uint n_bits, MEM_ROOT *mem_root)
   reexecution.
 
   @param tmp_columns the items that produce the data for the temp table
-  @param subquery_id subquery's identifier (for temptable name)
+  @param subquery_id subquery's identifier (to make "<subquery%d>" name for
+                                            EXPLAIN)
 
   @details
   - Create a temporary table to store the result of the IN subquery. The
@@ -3998,7 +3999,6 @@ subselect_hash_sj_engine::make_unique_engine()
   tab->table= tmp_table;
   tab->ref.tmp_table_index_lookup_init(thd, tmp_key, it, FALSE);
 
-
   DBUG_RETURN(new subselect_uniquesubquery_engine(thd, tab, item,
                                                   semi_join_conds));
 }

sql/sql_base.cc

@@ -7788,6 +7788,7 @@ bool setup_tables(THD *thd, Name_resolution_context *context,
       }
       DBUG_ASSERT(item == table_list->jtbm_subselect);
       table_list->jtbm_subselect->setup_engine(FALSE);
+      //psergey-merge: ^ todo: error checking!
     }
   }
 

sql/sql_class.cc

@@ -3033,7 +3033,8 @@ bool select_dumpvar::send_eof()
 }
 
 
-bool select_materialize_with_stats::
+bool
+select_materialize_with_stats::
 create_result_table(THD *thd_arg, List<Item> *column_types,
                     bool is_union_distinct, ulonglong options,
                     const char *table_alias, bool bit_fields_as_long)

sql/sql_join_cache.cc

@@ -1061,7 +1061,6 @@ int JOIN_CACHE::realloc_buffer()
 */
 
 int JOIN_CACHE::init()
-//psergey-merge:wtf is this here:  for (tab= start_tab; tab != join_tab; tab= next_linear_tab(join, tab, TRUE))
 {
   DBUG_ENTER("JOIN_CACHE::init");
 
@@ -3260,23 +3259,7 @@ uint JOIN_CACHE_HASHED::get_next_key(uchar ** key)
 
 int JOIN_TAB_SCAN::open()
 {
-  //psergey-merge: todo: check the below:
-  //JOIN_TAB *bound= join_tab-cache->tables;
-  
-#if 0
-  JOIN_TAB *bound= cache->start_tab;
-  
-  // psergey-todo-merge: can we really iterate backwards?
-  //   Q: is there really a need to iterate backwards?
-  
-  for (JOIN_TAB *tab= join_tab-1; tab != bound && !tab->cache; tab--)
-  {
-    tab->status= tab->table->status;
-    tab->table->status= 0;
-  }
-#endif
   save_or_restore_used_tabs(join_tab, FALSE);
-
   is_first_record= TRUE;
   return join_init_read_record(join_tab);
 }
@@ -3381,11 +3364,6 @@ void save_or_restore_used_tabs(JOIN_TAB *join_tab, bool save)
 
 void JOIN_TAB_SCAN::close()
 {
-#if 0
-  JOIN_TAB *bound= join_tab - cache->tables;
-  for (JOIN_TAB *tab= join_tab-1; tab != bound && !tab->cache; tab--)
-    tab->table->status= tab->status;
-#endif
   save_or_restore_used_tabs(join_tab, TRUE);
 }
 
@@ -3786,15 +3764,6 @@ int JOIN_TAB_SCAN_MRR::open()
   /* Dynamic range access is never used with BKA */
   DBUG_ASSERT(join_tab->use_quick != 2);
 
-/*
-psergey-merge: done?
-  JOIN_TAB *bound= join_tab - cache->tables;
-  for (JOIN_TAB *tab= join_tab-1; tab != bound && !tab->cache; tab--)
-  {
-    tab->status= tab->table->status;
-    tab->table->status= 0;
-  }
-*/
   save_or_restore_used_tabs(join_tab, FALSE);
 
   init_mrr_buff();

sql/sql_select.cc

@@ -2931,7 +2931,6 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables_arg, COND *conds,
       no_rows_const_tables |= table->map;
     }
   }
-
   stat_vector[i]=0;
   join->outer_join=outer_join;
 
@@ -7057,7 +7056,6 @@ inline void add_cond_and_fix(Item **e1, Item *e2)
 }
 
 
-
 /**
   Add to join_tab->select_cond[i] "table.field IS NOT NULL" conditions
   we've inferred from ref/eq_ref access performed.

sql/sql_select.h

@@ -162,7 +162,7 @@ typedef enum_nested_loop_state
   RETURN
      0     - OK
     -1     - Record not found
-    Other  - Error
+    Other  - A fatal error
 */
 typedef int (*Read_record_func)(struct st_join_table *tab);
 
@@ -446,7 +446,6 @@ typedef struct st_join_table {
   }
   void calc_used_field_length(bool max_fl);
   ulong get_used_fieldlength()
-
   {
     if (!used_fieldlength)
       calc_used_field_length(FALSE);