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, 25 insertions, 14 deletions

diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index f0bc582985b..0a1ea705a63 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -1905,8 +1905,7 @@ void st_select_lex::init_query()
   parent_lex->push_context(&context, parent_lex->thd->mem_root);
   cond_count= between_count= with_wild= 0;
   max_equal_elems= 0;
-  ref_pointer_array= 0;
-  ref_pointer_array_size= 0;
+  ref_pointer_array.reset();
   select_n_where_fields= 0;
   select_n_reserved= 0;
   select_n_having_items= 0;
@@ -1924,6 +1923,7 @@ void st_select_lex::init_query()
   prep_leaf_list_state= UNINIT;
   have_merged_subqueries= FALSE;
   bzero((char*) expr_cache_may_be_used, sizeof(expr_cache_may_be_used));
+  select_list_tables= 0;
   m_non_agg_field_used= false;
   m_agg_func_used= false;
 }
@@ -2421,7 +2421,7 @@ bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
                        select_n_having_items +
                        select_n_where_fields +
                        order_group_num) * 5;
-  if (ref_pointer_array != NULL)
+  if (!ref_pointer_array.is_null())
   {
     /*
       We need to take 'n_sum_items' into account when allocating the array,
@@ -2430,17 +2430,24 @@ bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
       In the usual case we can reuse the array from the prepare phase.
       If we need a bigger array, we must allocate a new one.
     */
-    if (ref_pointer_array_size >= n_elems)
-    {
-      DBUG_PRINT("info", ("reusing old ref_array"));
+    if (ref_pointer_array.size() == n_elems)
       return false;
-    }
-  }
-  ref_pointer_array= static_cast<Item**>(arena->alloc(sizeof(Item*) * n_elems));
-  if (ref_pointer_array != NULL)
-    ref_pointer_array_size= n_elems;
 
-  return ref_pointer_array == NULL;
+    /*
+      We need to take 'n_sum_items' into account when allocating the array,
+      and this may actually increase during the optimization phase due to
+      MIN/MAX rewrite in Item_in_subselect::single_value_transformer.
+      In the usual case we can reuse the array from the prepare phase.
+      If we need a bigger array, we must allocate a new one.
+     */
+    if (ref_pointer_array.size() == n_elems)
+      return false;
+   }
+  Item **array= static_cast<Item**>(arena->alloc(sizeof(Item*) * n_elems));
+  if (array != NULL)
+    ref_pointer_array= Ref_ptr_array(array, n_elems);
+
+  return array == NULL;
 }
 
 
@@ -2511,8 +2518,8 @@ void st_select_lex::print_order(String *str,
     }
     else
       (*order->item)->print(str, query_type);
-    if (!order->asc)
-      str->append(STRING_WITH_LEN(" desc"));
+    if (order->direction == ORDER::ORDER_DESC)
+       str->append(STRING_WITH_LEN(" desc"));
     if (order->next)
       str->append(',');
   }
@@ -3941,9 +3948,11 @@ void SELECT_LEX::update_used_tables()
 
   Item *item;
   List_iterator_fast<Item> it(join->fields_list);
+  select_list_tables= 0;
   while ((item= it++))
   {
     item->update_used_tables();
+    select_list_tables|= item->used_tables();
   }
   Item_outer_ref *ref;
   List_iterator_fast<Item_outer_ref> ref_it(inner_refs_list);
@@ -3993,6 +4002,8 @@ void st_select_lex::update_correlated_cache()
   if (join->conds)
     is_correlated|= MY_TEST(join->conds->used_tables() & OUTER_REF_TABLE_BIT);
 
+  is_correlated|= join->having_is_correlated;
+
   if (join->having)
     is_correlated|= MY_TEST(join->having->used_tables() & OUTER_REF_TABLE_BIT);