Merge

sql/sql_select.cc

@@ -798,117 +798,6 @@ err:
 }
 
 
-/*
-  Create a dummy temporary table, useful only for the sake of having a 
-  TABLE* object with map,tablenr and maybe_null properties.
-  
-  This is used by non-mergeable semi-join materilization code to handle
-  degenerate cases where materialized subquery produced "Impossible WHERE" 
-  and thus wasn't materialized.
-*/
-
-TABLE *create_dummy_tmp_table(THD *thd)
-{
-  DBUG_ENTER("create_dummy_tmp_table");
-  TABLE *table;
-  TMP_TABLE_PARAM sjm_table_param;
-  sjm_table_param.init();
-  sjm_table_param.field_count= 1;
-  List<Item> sjm_table_cols;
-  Item *column_item= new Item_int(1);
-  sjm_table_cols.push_back(column_item);
-  if (!(table= create_tmp_table(thd, &sjm_table_param, 
-                                sjm_table_cols, (ORDER*) 0, 
-                                TRUE /* distinct */, 
-                                1, /*save_sum_fields*/
-                                thd->options | TMP_TABLE_ALL_COLUMNS, 
-                                HA_POS_ERROR /*rows_limit */, 
-                                (char*)"dummy", TRUE /* Do not open */)))
-  {
-    DBUG_RETURN(NULL);
-  }
-  DBUG_RETURN(table);
-}
-
-
-void
-setup_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list, Item **join_where)
-{
-  TABLE_LIST *table;
-  NESTED_JOIN *nested_join;
-  List_iterator<TABLE_LIST> li(*join_list);
-  DBUG_ENTER("setup_jtbm_semi_joins");
-
-  
-  while ((table= li++))
-  {
-    Item_in_subselect *item;
-    
-    if ((item= table->jtbm_subselect))
-    {
-      Item_in_subselect *subq_pred= item;
-      double rows;
-      double read_time;
-
-      subq_pred->optimize(&rows, &read_time);
-      subq_pred->jtbm_read_time= read_time;
-      subq_pred->jtbm_record_count=rows;
-      subq_pred->is_jtbm_merged= TRUE;
-      JOIN *subq_join= subq_pred->unit->first_select()->join;
-      if (!subq_join->tables_list || !subq_join->table_count)
-      {
-        /*
-          This is an empty and constant table.
-
-          TODO: what if this is not empty but still constant?
-          
-          We'll need to check the equality but there's no materializatnion
-          table?
-
-          A: create an IN-equality from 
-           - left_expr
-           - right_expr. Q: how can right-expr exist in the context of 
-              parent select? We don't have refs from outside to inside!
-              A: create/check in the context of the child select?
-              
-              for injection, check how in->exists is performed.
-        */
-        subq_pred->is_jtbm_const_tab= TRUE;
-
-        TABLE *dummy_table= create_dummy_tmp_table(join->thd);
-        table->table= dummy_table;
-        table->table->pos_in_table_list= table;
-
-        setup_table_map(table->table, table, table->jtbm_table_no);
-      }
-      else
-      {
-        DBUG_ASSERT(subq_pred->test_set_strategy(SUBS_MATERIALIZATION));
-        subq_pred->is_jtbm_const_tab= FALSE;
-        subselect_hash_sj_engine *hash_sj_engine=
-          ((subselect_hash_sj_engine*)item->engine);
-        
-        table->table= hash_sj_engine->tmp_table;
-        table->table->pos_in_table_list= table;
-
-        setup_table_map(table->table, table, table->jtbm_table_no);
-
-        Item *sj_conds= hash_sj_engine->semi_join_conds;
-
-        (*join_where)= and_items(*join_where, sj_conds);
-        if (!(*join_where)->fixed)
-          (*join_where)->fix_fields(join->thd, join_where);
-      }
-    }
-
-    if ((nested_join= table->nested_join))
-    {
-      setup_jtbm_semi_joins(join, &nested_join->join_list, join_where);
-    }
-  }
-  DBUG_VOID_RETURN;
-}
-
 /**
   global select optimisation.
 
@@ -1030,7 +919,8 @@ JOIN::optimize()
       thd->restore_active_arena(arena, &backup);
   }
   
-  setup_jtbm_semi_joins(this, join_list, &conds);
+  if (setup_jtbm_semi_joins(this, join_list, &conds))
+    DBUG_RETURN(1);
 
   conds= optimize_cond(this, conds, join_list, &cond_value, &cond_equal);
      
@@ -15658,7 +15548,12 @@ join_read_const_table(JOIN_TAB *tab, POSITION *pos)
           tab->table->pos_in_table_list->jtbm_subselect->is_jtbm_const_tab)
   {
     /* Row will not be found */
-    DBUG_RETURN(-1);
+    int res;
+    if (tab->table->pos_in_table_list->jtbm_subselect->jtbm_const_row_found)
+      res= 0;
+    else
+      res= -1;
+    DBUG_RETURN(res);
   }
   else if (tab->type == JT_SYSTEM)
   {
@@ -21455,11 +21350,20 @@ void TABLE_LIST::print(THD *thd, table_map eliminated_tables, String *str,
   }
   else if (jtbm_subselect)
   {
-    str->append(STRING_WITH_LEN(" <materialize> ("));
-    subselect_hash_sj_engine *hash_engine;
-    hash_engine= (subselect_hash_sj_engine*)jtbm_subselect->engine;
-    hash_engine->materialize_engine->print(str, query_type);
-    str->append(')');
+    if (jtbm_subselect->is_jtbm_const_tab)
+    {
+      str->append(STRING_WITH_LEN(" <materialize> ("));
+      jtbm_subselect->engine->print(str, query_type);
+      str->append(')');
+    }
+    else
+    {
+      str->append(STRING_WITH_LEN(" <materialize> ("));
+      subselect_hash_sj_engine *hash_engine;
+      hash_engine= (subselect_hash_sj_engine*)jtbm_subselect->engine;
+      hash_engine->materialize_engine->print(str, query_type);
+      str->append(')');
+    }
   }
   else
   {