Merge branch '10.2' into 10.2-mdev9864

sql/sql_window.h

@@ -0,0 +1,230 @@
+
+#ifndef SQL_WINDOW_INCLUDED
+#define SQL_WINDOW_INCLUDED
+
+#include "my_global.h"
+#include "item.h"
+#include "filesort.h"
+#include "records.h"
+
+class Item_window_func;
+
+/*
+  Window functions module. 
+  
+  Each instance of window function has its own element in SELECT_LEX::window_specs.
+*/
+
+
+class Window_frame_bound : public Sql_alloc
+{
+
+public:
+ 
+  enum Bound_precedence_type
+  {
+    PRECEDING,
+    CURRENT,           // Used for CURRENT ROW window frame bounds
+    FOLLOWING
+  };
+
+  Bound_precedence_type precedence_type;
+ 
+
+  /* 
+    For UNBOUNDED PRECEDING / UNBOUNDED FOLLOWING window frame bounds
+    precedence type is seto to PRECEDING / FOLLOWING and
+    offset is set to NULL. 
+    The offset is not meaningful with precedence type CURRENT 
+  */
+  Item *offset;
+
+  Window_frame_bound(Bound_precedence_type prec_type,
+                     Item *offset_val)
+    : precedence_type(prec_type), offset(offset_val) {}
+
+  bool is_unbounded() { return offset == NULL; }
+
+};
+
+
+class Window_frame : public Sql_alloc
+{
+  
+public:
+
+  enum Frame_units
+  {
+    UNITS_ROWS,
+    UNITS_RANGE
+  };
+
+  enum Frame_exclusion
+  {
+    EXCL_NONE,
+    EXCL_CURRENT_ROW,
+    EXCL_GROUP,
+    EXCL_TIES
+  };
+
+  Frame_units units;
+
+  Window_frame_bound *top_bound;
+
+  Window_frame_bound *bottom_bound;
+
+  Frame_exclusion exclusion;
+
+  Window_frame(Frame_units win_frame_units,
+               Window_frame_bound *win_frame_top_bound,
+               Window_frame_bound *win_frame_bottom_bound,
+               Frame_exclusion win_frame_exclusion)
+    : units(win_frame_units), top_bound(win_frame_top_bound),
+      bottom_bound(win_frame_bottom_bound), exclusion(win_frame_exclusion) {}
+
+  bool check_frame_bounds();
+
+};
+
+class Window_spec : public Sql_alloc
+{
+  bool window_names_are_checked;
+ public:
+  virtual ~Window_spec() {}
+
+  LEX_STRING *window_ref;
+
+  SQL_I_List<ORDER> *partition_list;
+
+  SQL_I_List<ORDER> *order_list;
+
+  Window_frame *window_frame;
+
+  Window_spec *referenced_win_spec;
+
+  Window_spec(LEX_STRING *win_ref, 
+              SQL_I_List<ORDER> *part_list,
+              SQL_I_List<ORDER> *ord_list,
+              Window_frame *win_frame)
+    : window_names_are_checked(false), window_ref(win_ref),
+      partition_list(part_list), order_list(ord_list),
+      window_frame(win_frame), referenced_win_spec(NULL) {}
+
+  virtual char *name() { return NULL; }
+
+  bool check_window_names(List_iterator_fast<Window_spec> &it);
+
+  char *window_reference() { return window_ref ? window_ref->str : NULL; }
+
+  void join_partition_and_order_lists()
+  {
+    *(partition_list->next)= order_list->first;
+  }
+
+  void disjoin_partition_and_order_lists()
+  {
+    *(partition_list->next)= NULL;
+  }
+};
+
+class Window_def : public Window_spec
+{
+ public:
+
+  LEX_STRING *window_name;
+
+  Window_def(LEX_STRING *win_name,
+             LEX_STRING *win_ref, 
+             SQL_I_List<ORDER> *part_list,
+             SQL_I_List<ORDER> *ord_list,
+             Window_frame *win_frame) 
+    : Window_spec(win_ref, part_list, ord_list, win_frame),
+      window_name(win_name) {}
+ 
+  char *name() { return window_name->str; }
+
+};
+
+int setup_windows(THD *thd, Ref_ptr_array ref_pointer_array, TABLE_LIST *tables,
+	          List<Item> &fields, List<Item> &all_fields, 
+                  List<Window_spec> &win_specs, List<Item_window_func> &win_funcs);
+
+
+//////////////////////////////////////////////////////////////////////////////
+// Classes that make window functions computation a part of SELECT's query plan
+//////////////////////////////////////////////////////////////////////////////
+
+typedef bool (*window_compute_func_t)(Item_window_func *item_win,
+                                      TABLE *tbl, READ_RECORD *info);
+
+/*
+  This handles computation of one window function.
+
+  Currently, we make a spearate filesort() call for each window function.
+*/
+
+class Window_func_runner : public Sql_alloc
+{
+  Item_window_func *win_func;
+
+  /* The function to use for computation*/
+  window_compute_func_t compute_func;
+
+public:
+  Window_func_runner(Item_window_func *win_func_arg) :
+    win_func(win_func_arg)
+  {}
+
+  // Set things up. Create filesort structures, etc
+  bool setup(THD *thd);
+ 
+  // This sorts and runs the window function.
+  bool exec(TABLE *tbl, SORT_INFO *filesort_result);
+};
+
+
+/*
+  Represents a group of window functions that require the same sorting of 
+  rows and so share the filesort() call.
+
+*/
+
+class Window_funcs_sort : public Sql_alloc
+{
+  List<Window_func_runner> runners;
+
+  /* Window functions can be computed over this sorting */
+  Filesort *filesort;
+public:
+  bool setup(THD *thd, SQL_SELECT *sel, List_iterator<Item_window_func> &it);
+  bool exec(JOIN *join);
+  void cleanup() { delete filesort; }
+
+  friend class Window_funcs_computation;
+};
+
+
+struct st_join_table;
+class Explain_aggr_window_funcs;
+/*
+  This is a "window function computation phase": a single object of this class
+  takes care of computing all window functions in a SELECT.
+
+  - JOIN optimizer is exected to call setup() during query optimization.
+  - JOIN::exec() should call exec() once it has collected join output in a
+    temporary table.
+*/
+
+class Window_funcs_computation : public Sql_alloc
+{
+  List<Window_funcs_sort> win_func_sorts;
+public:
+  bool setup(THD *thd, List<Item_window_func> *window_funcs, st_join_table *tab);
+  bool exec(JOIN *join);
+
+  Explain_aggr_window_funcs *save_explain_plan(MEM_ROOT *mem_root, bool is_analyze);
+  void cleanup();
+};
+
+
+#endif /* SQL_WINDOW_INCLUDED */