This is the consolidated patch for mdev-8646:bb-10.2-mdev8646

"Re-factor the code for post-join operations".

The patch mainly contains the code ported from mysql-5.6 and
created for two essential architectural changes:
1. WL#5558: Resolve ORDER BY execution method at the optimization stage
2. WL#6071: Inline tmp tables into the nested loops algorithm

The first task was implemented for mysql-5.6 by Ole John Aske.
It allows to make all decisions on ORDER BY operation at the optimization
stage.

The second task implemented for mysql-5.6 by Evgeny Potemkin adds JOIN_TAB
nodes for post-join operations that require temporary tables. It allows
to execute these operations within the nested loops algorithm that used to
be used before this task only for join queries. Besides these task moves
all planning on the execution of these operations from the execution phase
to the optimization phase.

Some other re-factoring changes of mysql-5.6 were pulled in, mainly because
it was easier to pull them in than roll them back. In particular all
changes concerning Ref_ptr_array were incorporated.

The port required some changes in the MariaDB code that concerned the
functionality of EXPLAIN and ANALYZE. This was done mainly by Sergey
Petrunia.

1 files changed, 15 insertions, 24 deletions

diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index 069eadc7519..4dac37eb563 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -437,8 +437,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
 
     can_skip_order_by= is_union_select && !(sl->braces && sl->explicit_limit);
 
-    saved_error= join->prepare(&sl->ref_pointer_array,
-                               sl->table_list.first,
+    saved_error= join->prepare(sl->table_list.first,
                                sl->with_wild,
                                sl->where,
                                (can_skip_order_by ? 0 :
@@ -647,8 +646,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
         fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items;
 
 	saved_error= fake_select_lex->join->
-	  prepare(&fake_select_lex->ref_pointer_array,
-		  fake_select_lex->table_list.first,
+	  prepare(fake_select_lex->table_list.first,
 		  0, 0,
                   global_parameters()->order_list.elements, // og_num
                   global_parameters()->order_list.first,    // order
@@ -703,7 +701,7 @@ bool st_select_lex_unit::optimize()
       {
         item->assigned(0); // We will reinit & rexecute unit
         item->reset();
-        if (table->created)
+        if (table->is_created())
         {
           table->file->ha_delete_all_rows();
           table->file->info(HA_STATUS_VARIABLE);
@@ -947,13 +945,13 @@ bool st_select_lex_unit::exec()
           Don't add more sum_items if we have already done JOIN::prepare
           for this (with a different join object)
         */
-        if (!fake_select_lex->ref_pointer_array)
+        if (fake_select_lex->ref_pointer_array.is_null())
           fake_select_lex->n_child_sum_items+= global_parameters()->n_sum_items;
         
         if (!was_executed)
           save_union_explain_part2(thd->lex->explain);
 
-        saved_error= mysql_select(thd, &fake_select_lex->ref_pointer_array,
+        saved_error= mysql_select(thd,
                               &result_table_list,
                               0, item_list, NULL,
 				  global_parameters()->order_list.elements,
@@ -976,7 +974,7 @@ bool st_select_lex_unit::exec()
             to reset them back, we re-do all of the actions (yes it is ugly):
           */ // psergey-todo: is the above really necessary anymore?? 
 	  join->init(thd, item_list, fake_select_lex->options, result);
-          saved_error= mysql_select(thd, &fake_select_lex->ref_pointer_array,
+          saved_error= mysql_select(thd,
                                 &result_table_list,
                                 0, item_list, NULL,
 				    global_parameters()->order_list.elements,
@@ -1023,27 +1021,11 @@ bool st_select_lex_unit::cleanup()
   }
   cleaned= 1;
 
-  if (union_result)
-  {
-    delete union_result;
-    union_result=0; // Safety
-    if (table)
-      free_tmp_table(thd, table);
-    table= 0; // Safety
-  }
-
   for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
     error|= sl->cleanup();
 
   if (fake_select_lex)
   {
-    JOIN *join;
-    if ((join= fake_select_lex->join))
-    {
-      join->tables_list= 0;
-      join->table_count= 0;
-      join->top_join_tab_count= 0;
-    }
     error|= fake_select_lex->cleanup();
     /*
       There are two cases when we should clean order items:
@@ -1065,6 +1047,15 @@ bool st_select_lex_unit::cleanup()
     }
   }
 
+  if (union_result)
+  {
+    delete union_result;
+    union_result=0; // Safety
+    if (table)
+      free_tmp_table(thd, table);
+    table= 0; // Safety
+  }
+
   DBUG_RETURN(error);
 }