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, 46 insertions, 6 deletions

diff --git a/sql/filesort.h b/sql/filesort.h
index 22d7f987de2..b92b87bee2e 100644
--- a/sql/filesort.h
+++ b/sql/filesort.h
@@ -20,18 +20,58 @@ class SQL_SELECT;
 
 #include "my_global.h"                          /* uint, uchar */
 #include "my_base.h"                            /* ha_rows */
+#include "sql_list.h"                           /* Sql_alloc */
 
 class SQL_SELECT;
 class THD;
 struct TABLE;
-struct SORT_FIELD;
 class Filesort_tracker;
+struct SORT_FIELD;
+typedef struct st_order ORDER;
+ 
+
+/**
+  Sorting related info.
+  To be extended by another WL to include complete filesort implementation.
+*/
+class Filesort: public Sql_alloc
+{
+public:
+  /** List of expressions to order the table by */
+  ORDER *order;
+  /** Number of records to return */
+  ha_rows limit;
+  /** ORDER BY list with some precalculated info for filesort */
+  SORT_FIELD *sortorder;
+  /** select to use for getting records */
+  SQL_SELECT *select;
+  /** TRUE <=> free select on destruction */
+  bool own_select;
+  /** true means we are using Priority Queue for order by with limit. */
+  bool using_pq;
+
+  Filesort(ORDER *order_arg, ha_rows limit_arg, SQL_SELECT *select_arg):
+    order(order_arg),
+    limit(limit_arg),
+    sortorder(NULL),
+    select(select_arg),
+    own_select(false), 
+    using_pq(false)
+  {
+    DBUG_ASSERT(order);
+  };
+
+  ~Filesort() { cleanup(); }
+  /* Prepare ORDER BY list for sorting. */
+  uint make_sortorder(THD *thd);
+
+private:
+  void cleanup();
+};
 
-ha_rows filesort(THD *thd, TABLE *table, SORT_FIELD *sortorder,
-                 uint s_length, SQL_SELECT *select,
-                 ha_rows max_rows, bool sort_positions,
-                 ha_rows *examined_rows, ha_rows *found_rows,
-                 Filesort_tracker* tracker);
+ha_rows filesort(THD *thd, TABLE *table, Filesort *filesort,
+                 bool sort_positions, ha_rows *examined_rows,
+                 ha_rows *found_rows, Filesort_tracker* tracker);
 void filesort_free_buffers(TABLE *table, bool full);
 void change_double_for_sort(double nr,uchar *to);