Current File : //usr/include/mysql/server/private/sql_window.h
/*
Copyright (c) 2016, 2022 MariaDB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef SQL_WINDOW_INCLUDED
#define SQL_WINDOW_INCLUDED
#include "filesort.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; }
void print(String *str, enum_query_type query_type);
};
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();
void print(String *str, enum_query_type query_type);
};
class Window_spec : public Sql_alloc
{
bool window_names_are_checked;
public:
virtual ~Window_spec() = default;
LEX_CSTRING *window_ref;
SQL_I_List<ORDER> *partition_list;
SQL_I_List<ORDER> *save_partition_list;
SQL_I_List<ORDER> *order_list;
SQL_I_List<ORDER> *save_order_list;
Window_frame *window_frame;
Window_spec *referenced_win_spec;
/*
Window_spec objects are numbered by the number of their appearance in the
query. This is used by compare_order_elements() to provide a predictable
ordering of PARTITION/ORDER BY clauses.
*/
int win_spec_number;
Window_spec(LEX_CSTRING *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), save_partition_list(NULL),
order_list(ord_list), save_order_list(NULL),
window_frame(win_frame), referenced_win_spec(NULL) {}
virtual const char *name() { return NULL; }
bool check_window_names(List_iterator_fast<Window_spec> &it);
const 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;
}
void print(String *str, enum_query_type query_type);
void print_order(String *str, enum_query_type query_type);
void print_partition(String *str, enum_query_type query_type);
};
class Window_def : public Window_spec
{
public:
LEX_CSTRING *window_name;
Window_def(LEX_CSTRING *win_name,
LEX_CSTRING *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) {}
const char *name() override { 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
//////////////////////////////////////////////////////////////////////////////
class Frame_cursor;
/*
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
{
public:
/* Add the function to be computed during the execution pass */
bool add_function_to_run(Item_window_func *win_func);
/* Compute and fill the fields in the table. */
bool exec(THD *thd, TABLE *tbl, SORT_INFO *filesort_result);
private:
/* A list of window functions for which this Window_func_runner will compute
values during the execution phase. */
List<Item_window_func> window_functions;
};
/*
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
{
public:
bool setup(THD *thd, SQL_SELECT *sel, List_iterator<Item_window_func> &it,
st_join_table *join_tab);
bool exec(JOIN *join, bool keep_filesort_result);
void cleanup() { delete filesort; }
friend class Window_funcs_computation;
private:
Window_func_runner runner;
/* Window functions can be computed over this sorting */
Filesort *filesort;
};
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, bool keep_last_filesort_result);
Explain_aggr_window_funcs *save_explain_plan(MEM_ROOT *mem_root, bool is_analyze);
void cleanup();
};
#endif /* SQL_WINDOW_INCLUDED */
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