MySQL 8.0.31
Source Code Documentation
window.h
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22*/
23
24#ifndef WINDOWS_INCLUDED
25#define WINDOWS_INCLUDED
26
27#include <assert.h>
28#include <sys/types.h>
29#include <cstring> // std::memcpy
30
31#include "my_inttypes.h"
32#include "sql/enum_query_type.h"
33#include "sql/handler.h"
34#include "sql/mem_root_array.h"
35#include "sql/sql_lex.h"
36#include "sql/sql_list.h"
37#include "sql/table.h"
38
39/*
40 Some Window-related symbols must be known to sql_lex.h which is a frequently
41 included header.
42 To avoid that any change to window.h causes a recompilation of the whole
43 Server, those symbols go into this header:
44*/
45#include "sql/window_lex.h"
46
47class Cached_item;
48class Item;
49class Item_func;
50class Item_string;
51class Item_sum;
52class PT_border;
53class PT_frame;
54class PT_order_list;
55class PT_window;
56class String;
57class THD;
59
60/**
61 Position hints for the frame buffer are saved for these kind of row
62 accesses, cf. #Window::m_frame_buffer_positions.
63*/
65 WONT_UPDATE_HINT = -1, // special value when using restore_special_row
67 CURRENT = 1,
69 LAST_IN_FRAME = 3,
71 MISC_POSITIONS = 5 // NTH_VALUE, LEAD/LAG have dynamic indexes 5..N
72};
73
74/**
75 The number of windows is limited to avoid the stack blowing up
76 when constructing iterators recursively. There used to be no limit, but
77 it would be unsafe since QEP_shared::m_idx of tmp tables assigned for windows
78 would exceed the old range of its type plan_idx (int8). It
79 has now been widened, so the max number of windows could be increased
80 if need be, modulo other problems. We could also make it a system variable.
81*/
82constexpr int kMaxWindows = 127;
83
84/**
85 Represents the (explicit) window of a SQL 2003 section 7.11 <window clause>,
86 or the implicit (inlined) window of a window function call, or a reference to
87 a named window in a window function call (instead of the inlined definition)
88 before resolution. After resolving referencing instances become unused,
89 having been replaced with the window resolved to in the w.f. call.
90
91 @verbatim
92 Cf. 7.11 <window definition> and <existing window name>
93 6.10 <window name or specification> and
94 <in-line window specification>
95 5.4 <window name>
96 @endverbatim
97
98 See also PT_window (which wraps Window as a parse_tree_node), and the related
99 classes PT_frame, PT_border and PT_exclusion in parse_tree_nodes.
100
101 Currently includes both prepared query and execution state information.
102 The latter is marked as such for ease of separation later.
103*/
104class Window {
105 /*------------------------------------------------------------------------
106 *
107 * Variables stable during execution
108 *
109 *------------------------------------------------------------------------*/
110 protected:
111 Query_block *m_query_block; ///< The SELECT the window is on
112 PT_order_list *const m_partition_by; ///< <window partition clause>
113 PT_order_list *const m_order_by; ///< <window order clause>
114 ORDER *m_sorting_order; ///< merged partition/order by
115 PT_frame *const m_frame; ///< <window frame clause>
116 Item_string *m_name; ///< <window name>
117 /**
118 Position of definition in query's text, 1 for leftmost. References don't
119 count. Thus, anonymous windows in SELECT list, then windows of WINDOW
120 clause, then anonymous windows in ORDER BY.
121 */
123 Item_string *const m_inherit_from; ///< <existing window name>
124 /**
125 If true, m_name is an unbound window reference, other fields
126 are unused.
127 */
128 const bool m_is_reference;
129
130 /**
131 (At least) one window function needs to buffer frame rows for evaluation
132 i.e. it cannot be evaluated on the fly just from previous rows seen
133 */
135
136 /**
137 (At least) one window function needs the peer set of the current row to
138 evaluate the wf for the current row
139 */
141
142 /**
143 (At least) one window function (currently JSON_OBJECTAGG) needs the
144 last peer for the current row to evaluate the wf for the current row.
145 (This is used only during inversion/optimization)
146 */
148
149 /**
150 (At least) one window function needs the cardinality of the partition of
151 the current row to evaluate the wf for the current row
152 */
154
155 /**
156 The functions are optimizable with ROW unit. For example SUM is, MAX is
157 not always optimizable. Optimized means we can use the optimized evaluation
158 path in process_buffered_windowing_record which uses inversion to avoid
159 revisiting all frame rows for every row being evaluated.
160 */
162
163 /**
164 The functions are optimizable with RANGE unit. For example SUM is, MAX is
165 not always optimizable. Optimized means we can use the optimized evaluation
166 path in process_buffered_windowing_record which uses inversion to avoid
167 revisiting all frame rows for every row being evaluated.
168 */
170
171 /**
172 The aggregates (SUM, etc) can be evaluated once for a partition, since it
173 is static, i.e. all rows will have the same value for the aggregates, e.g.
174 ROWS/RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING.
175 */
177
178 /**
179 Window equires re-evaluation of the first row in optimized moving frame mode
180 e.g. FIRST_VALUE.
181 */
183
184 /**
185 Window requires re-evaluation of the last row in optimized moving frame mode
186 e.g. LAST_VALUE.
187 */
189
190 /**
191 The last window to be evaluated at execution time.
192 */
193 bool m_last;
194
195 public:
196 struct st_offset {
199 st_offset() : m_rowno(0), m_from_last(false) {}
200 /**
201 Used for sorting offsets in ascending order for faster traversal of
202 frame buffer tmp file
203 */
204 bool operator<(const st_offset &a) const { return m_rowno < a.m_rowno; }
205 };
206
208 int64 m_rowno; ///< negative values is LEAD
209 st_ll_offset() : m_rowno(INT_MIN64 /* uninitialized marker*/) {}
210 /**
211 Used for sorting offsets in ascending order for faster traversal of
212 frame buffer tmp file
213 */
214 bool operator<(const st_ll_offset &a) const { return m_rowno < a.m_rowno; }
215 };
216
217 struct st_nth {
219 m_offsets; ///< sorted set of NTH_VALUE offsets
220 };
221
222 struct st_lead_lag {
224 m_offsets; ///< sorted set of LEAD/LAG offsets
225 };
226
227 protected:
228 /**
229 Window requires re-evaluation of the Nth row in optimized moving frame mode
230 e.g. NTH_VALUE.
231 */
234
235 protected:
236 const Window *m_ancestor; ///< resolved from existing window name
237 List<Item_sum> m_functions; ///< window functions based on 'this'
239 m_partition_items; ///< items for the PARTITION BY columns
241 m_order_by_items; ///< items for the ORDER BY exprs.
242
243 /*------------------------------------------------------------------------
244 *
245 * Execution state variables
246 *
247 *------------------------------------------------------------------------*/
248 public:
249 /**
250 Cardinality of m_frame_buffer_positions if no NTH_VALUE, LEAD/LAG
251 */
252 static constexpr int FRAME_BUFFER_POSITIONS_CARD =
254
255 /**
256 Holds information about a position in the buffer frame as stored in a
257 temporary file (cf. m_frame_buffer). We save a number of such positions
258 to speed up lookup when we move the window frame, cf.
259 m_frame_buffer_positions
260 */
262 ///< The size of the file position is determined by handler::ref_length
264 ///< Row number in partition, 1-based
267 : m_position(position), m_rowno(rowno) {}
268 };
269
270 /**
271 Execution state: used iff m_needs_frame_buffering. Holds pointers to
272 positions in the file in m_frame_buffer. We use these saved positions to
273 avoid having to position to the first row in the partition and then
274 making many read calls to find the desired row. By repositioning to a
275 suitably(*) saved position we normally (**) need to do only one positioned
276 read and one ha_rdn_next call to get at a desired row.
277 @verbatim
278
279 [0] the first row in the partition: at the
280 beginning of a new partition that is the first row in the partition.
281 Its rowno == 1 by definition.
282 [1] position of the current row N (for jump-back to current row or next
283 current row in combo with ha_rnd_next)
284 [2] position of the current first row M in frame (for aggregation looping
285 jump-back)
286 [3] position of the current last row in a frame
287 [4] position and line number of the row last read
288 and optionally:
289 [5..X] positions of Nth row of X-5+1 NTH_VALUE functions invoked on window
290 [X+1..Y] position of last row of lead/lag functions invoked on window
291
292 @endverbatim
293 Pointers are lazily initialized if needed.
294
295 (*) We use the position closest below the desired position, cf logic in
296 read_frame_buffer_row.
297
298 (**) Unless we have a frame beyond the current row, in which case we need
299 to do some scanning for the first row in the partition.
300 Also NTH_VALUE with RANGE might sometimes needs to read several rows, since
301 the frame start can jump several rows ahead when the current row moves
302 forward.
303 */
305
306 /**
307 Sometimes we read one row too many, so that the saved position will
308 be too far out because we subsequently need to read an earlier (previous)
309 row of the same kind (reason). For such cases, we first save the
310 current position, read, and if we see we read too far, restore the old
311 position. See #save_pos and #restore_pos.
312 */
314
315 /**
316 See #m_tmp_pos
317 */
319 int reason_index = static_cast<int>(reason);
320 m_tmp_pos.m_rowno = m_frame_buffer_positions[reason_index].m_rowno;
321 std::memcpy(m_tmp_pos.m_position,
322 m_frame_buffer_positions[reason_index].m_position,
323 frame_buffer()->file->ref_length);
324 }
325
326 /**
327 See #m_tmp_pos
328 */
330 int reason_index = static_cast<int>(reason);
331 m_frame_buffer_positions[reason_index].m_rowno = m_tmp_pos.m_rowno;
332 std::memcpy(m_frame_buffer_positions[reason_index].m_position,
333 m_tmp_pos.m_position, frame_buffer()->file->ref_length);
334 }
335
336 /**
337 Copy frame buffer position hint from one to another.
338 */
341 int from_index = static_cast<int>(from_reason);
342 int to_index = static_cast<int>(to_reason);
343 m_frame_buffer_positions[to_index].m_rowno =
344 m_frame_buffer_positions[from_index].m_rowno;
345
346 std::memcpy(m_frame_buffer_positions[to_index].m_position,
347 m_frame_buffer_positions[from_index].m_position,
348 frame_buffer()->file->ref_length);
349 }
350
351 /**
352 Keys for m_special_rows_cache, for special
353 rows (see the comment on m_special_row_cache). Note that they are negative,
354 so that they will never collide with actual row numbers in the frame.
355 This allows us to treat them interchangeably with real row numbers
356 as function arguments; e.g., bring_back_frame_row() can restore either
357 a “normal” row from the frame, or one of the special rows, and does not
358 need to take in separate flags for the two.
359 TODO(Chaithra): We have only one special key. Do we need the enum?
360 Also m_special_rows_cache/cache_length/max_cache_length should be looked
361 into.
362 */
364 /**
365 We read an incoming row. We notice it is the start of a new
366 partition. We must thus process the just-finished partition, but that
367 processing uses this row's buffer; so, we save this row first, process
368 the partition, and restore it later.
369 */
371 // Insert new values here.
372 // And keep the ones below up to date.
375 };
376
377 protected:
378 /**
379 Execution state: used iff m_needs_frame_buffering. Holds the temporary
380 file (used for the frame buffering) parameters
381 */
383
384 /**
385 Holds whether this window should be “short-circuit”, ie., goes directly
386 to the query output instead of to a temporary table.
387 */
388 bool m_short_circuit = false;
389
390 /**
391 Execution state: used iff m_needs_frame_buffering. Holds the TABLE
392 object for the the temporary file used for the frame buffering.
393 */
395
396 /**
397 Execution state: The frame buffer tmp file is not truncated for each new
398 partition. We need to keep track of where a partition starts in case we
399 need to switch from heap to innodb tmp file on overflow, in order to
400 re-initialize m_frame_buffer_positions with the current partition's row 1
401 (which is the minimum hint required) as we cross over. This number is
402 incremented for each write.
403 */
405
406 /**
407 Execution state: Snapshot of m_frame_buffer_total_rows when we start a new
408 partition, i.e. for the first row in the first partition we will have a
409 value of 1.
410 */
412
413 /**
414 If >=1: the row with this number (1-based, relative to start of
415 partition) currently has its fields in the record buffer of the IN table
416 and of the OUT table. 0 means "unset".
417 Usable only with buffering. Set and read by bring_back_frame_row(), so
418 that multiple successive calls to it for same row do only one read from
419 FB (optimization).
420 */
422
423 /**
424 Holds a fixed number of copies of special rows; each copy can use up to
425 #m_special_rows_cache_max_length bytes. Special rows are those that are
426 not part of our frame, but that we need to store away nevertheless, because
427 they might be in the table's buffers, which we need for our own purposes
428 during window processing.
429 cf. the Special_keys enumeration.
430 */
432 /// Length of each copy in #m_special_rows_cache, in bytes
434 /// Maximum allocated size in #m_special_rows_cache
436
437 /**
438 Execution state: used iff m_needs_frame_buffering. Holds the row
439 number (in the partition) of the last row (hitherto) saved in the frame
440 buffer
441 */
443
444 /**
445 Execution state: used iff m_needs_peerset. Holds the rowno
446 for the last row in this peer set.
447 */
449
450 /**
451 Execution state: used iff m_needs_last_peer_in_frame. True if a row
452 leaving the frame is the last row in the peer set within the frame.
453 */
455
456 /**
457 Execution state: the current row number in the current partition.
458 Set in check_partition_boundary. Used while reading input rows, in contrast
459 to m_rowno_in_partition, which is used when processing buffered rows.
460 Cf. check_partition_boundary.
461 */
463
464 /**
465 Execution state: the current row starts a new partition.
466 Set in check_partition_boundary.
467 */
469
470 /**
471 Execution state: The number, in the current partition, of the last output
472 row, i.e. the row number of the last row hitherto evaluated and output to
473 the next phase.
474 */
476
477 /**
478 Execution state: The number of the row being visited for its contribution
479 to a window function, relative to the start of the partition. Note that
480 this will often be different from the current row for which we are
481 processing the window function, reading it for output. That is given by
482 m_rowno_in_partition, q.v.
483 */
485
486 /**
487 Execution state: the row number of the current row within a frame, cf.
488 m_is_last_row_in_frame, relative to start of the frame. 1-based.
489 */
491
492 /**
493 Execution state: The row number of the current row being readied for
494 output within the partition. 1-based.
495 */
497
498 /**
499 Execution state: for optimizable aggregates, cf. m_row_optimizable and
500 m_range_optimizable, we need to keep track of when we have computed the
501 first aggregate, since aggregates for rows 2..N are computed in an optimized
502 way by inverse aggregation of the row moving out of the frame.
503 */
505
506 /*------------------------------------------------------------------------
507 *
508 * RANGE boundary frame state variables.
509 *
510 *------------------------------------------------------------------------*/
511 public:
512 /*
513 For RANGE bounds, we need to be able to check if a given row is
514 before the lower bound, or after the upper bound, as we don't know
515 ahead of time how many rows to skip (unlike for ROW bounds).
516 Often, the lower and upper bounds are the same, as they are
517 inclusive.
518
519 We solve this by having an array of comparators of the type
520
521 value ⋛ <cache>(ref_value)
522
523 where ⋛ is a three-way comparator, and <cache>(ref_value) is an
524 Item_cache where we can store the value of the reference row
525 before we invoke the comparison. For instance, if we have a
526 row bound such as
527
528 ... OVER (ORDER BY a,b) FROM t1
529
530 we will have an array with the two comparators
531
532 t1.a ⋛ <cache>(a)
533 t1.b ⋛ <cache>(b)
534
535 and when we evaluate the frame bounds for a given row, we insert
536 the reference values in the caches and then do the comparison to
537 figure out if we're before, in or after the bound. As this is a
538 lexicographic comparison, we only need to evaluate the second
539 comparator if the first one returns equality.
540
541 The expressions on the right-hand side can be somewhat more
542 complicated; say that we have a window specification like
543
544 ... OVER (ORDER BY a RANGE BETWEEN 2 PRECEDING AND 3 FOLLOWING)
545
546 In this case, the lower bound and upper bound are different
547 (both arrays will always contain only a single element):
548
549 Lower: t1.a ⋛ <cache>(a) - 2
550 Upper: t1.a ⋛ <cache>(a) + 3
551
552 ie., there is an Item_func_plus or Item_func_minus with some
553 constant expression as the second argument.
554
555 The comparators for the lower bound is stored in [0], and for
556 the upper bound in [1].
557 */
559
560 /**
561 The logical ordering index (into LogicalOrderings) needed by this window's
562 PARTITION BY and ORDER BY clauses together (if any; else, 0). Used only by
563 the hypergraph join optimizer.
564 */
566
567 /**
568 Used temporarily by the hypergraph join optimizer to mark which windows
569 are referred to by a given ordering (so that one doesn't try to satisfy
570 a window's ordering by an ordering referring to that window).
571 */
572 bool m_mark;
573
574 protected:
575 /**
576 Execution state: the row number of the first row in a frame when evaluating
577 RANGE based frame bounds. When using RANGE bounds, we don't know a priori
578 when moving the frame which row number will be the next lower bound, but
579 we know it will have to be a row number higher than the lower bound of
580 the previous frame, since the bounds increase monotonically as long
581 as the frame bounds are static within the query (current limitation).
582 So, it makes sense to remember the first row number in a frame until
583 we have determined the start of the next frame.
584
585 If the frame for the previous current row in the partition was empty (cf.
586 "current_row" in process_buffered_windowing_record), this should point
587 to the next possible frame start. Relative to partition start, 1-based.
588 */
590
591 /**
592 Execution state: used for RANGE bounds frame evaluation
593 for the continued evaluation for current row > 2 in a partition.
594 If the frame for the current row visited (cf "current_row" in
595 process_buffered_windowing_record) was empty, the invariant
596
597 m_last_rowno_in_range_frame < m_first_rowno_in_range_frame
598
599 should hold after the visit. Relative to partition start. 1-based.
600 */
602
603 /*------------------------------------------------------------------------
604 *
605 * Window function special behaviour toggles. These boolean flag influence
606 * the action taken when a window function is evaluated, i.e.
607 *
608 * Item_xxx::val_xxx
609 *
610 * They are set locally just before and after a call to evaluate functions,
611 * i.e.
612 *
613 * w.set_<toggle>(true)
614 * copy_<kind>_window_functions() [see process_buffered_windowing_record]
615 * w.set_<toggle>(false)
616 *
617 * to achieve a special semantic, since we cannot pass down extra parameters.
618 *
619 *------------------------------------------------------------------------*/
620
621 /**
622 Execution state: the current row is the last row in a window frame
623 For some aggregate functions, e.g AVG, we can save computation by not
624 evaluating the entire function value before the last row has been read.
625 For AVG, do the summation for each row in the frame, but the division only
626 for the last row, at which time the result is needed for the wf.
627 Probably only useful for ROW based or static frames.
628 For frame with peer set computation, determining the last row in the
629 peer set ahead of processing is not possible, so we use a pessimistic
630 assumption.
631 */
633
634 /**
635 Execution state: make frame wf produce a NULL (or 0 depending, e.g. if
636 COUNT) value because no rows are available for aggregation: e.g. for first
637 row in partition if frame is ROWS BETWEEN 2 PRECEDING and 1 PRECEDING has
638 no rows for which aggregation can happen
639 */
641
642 /**
643 Execution state: do inverse, e.g. subtract rather than add in aggregates.
644 Used for optimizing computation of sliding frames for eligible aggregates,
645 cf. Item_sum::check_wf_semantics.
646 */
648
649 /*------------------------------------------------------------------------
650 *
651 * Constructors
652 *
653 *------------------------------------------------------------------------*/
654 private:
655 /**
656 Generic window constructor, shared
657 */
659 PT_frame *frame, bool is_reference, Item_string *inherit)
661 m_partition_by(part),
662 m_order_by(ord),
664 m_frame(frame),
665 m_name(name),
666 m_def_pos(0),
667 m_inherit_from(inherit),
670 m_needs_peerset(false),
673 m_row_optimizable(true),
675 m_static_aggregates(false),
676 m_opt_first_row(false),
677 m_opt_last_row(false),
678 m_last(false),
682 m_tmp_pos(nullptr, -1),
693 m_partition_border(true),
698 m_aggregates_primed(false),
702 m_do_copy_null(false),
703 m_inverse_aggregation(false) {
704 m_opt_nth_row.m_offsets.init_empty_const();
705 m_opt_lead_lag.m_offsets.init_empty_const();
706 m_frame_buffer_positions.init_empty_const();
707 }
708
709 public:
710 /**
711 Reference to a named window. This kind is only used before resolution,
712 references to it being replaced by the referenced window object thereafter.
713 */
715 : Window(name, nullptr, nullptr, nullptr, true, nullptr) {}
716
717 /**
718 Unnamed window. If the window turns out to be named, the name will be set
719 later, cf. #set_name().
720 */
721 Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame)
722 : Window(nullptr, partition_by, order_by, frame, false, nullptr) {}
723
724 /**
725 Unnamed window based on a named window. If the window turns out to be
726 named, the name will be set later, cf. #set_name().
727 */
728 Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame,
729 Item_string *inherit)
730 : Window(nullptr, partition_by, order_by, frame, false, inherit) {}
731
732 /*------------------------------------------------------------------------
733 *
734 * Methods
735 *
736 *------------------------------------------------------------------------*/
737
738 /**
739 We have a named window. Now set its name. Used once, if at all, for a
740 window as part of parsing.
741 */
743
744 /**
745 After resolving an existing window name reference in a window definition,
746 we set the ancestor pointer to easy access later.
747 */
749
750 /**
751 Get the name of a window. Can be empty, cf. #printable_name which is not.
752 */
753 Item_string *name() const { return m_name; }
754
755 uint def_pos() const { return m_def_pos; } ///< @see #m_def_pos
756 void set_def_pos(uint pos) { m_def_pos = pos; } ///< @see #m_def_pos
757
758 /**
759 Get the frame, if any. SQL 2011 7.11 GR 1.b.i.6
760 */
761 const PT_frame *frame() const { return m_frame; }
762
763 /**
764 Get the ORDER BY, if any. That is, the first we find along
765 the ancestor chain. Uniqueness checked in #setup_windows1
766 SQL 2011 7.11 GR 1.b.i.5.A-C
767 */
769 const PT_order_list *o = m_order_by;
770 const Window *w = m_ancestor;
771
772 while (o == nullptr && w != nullptr) {
773 o = w->m_order_by;
774 w = w->m_ancestor;
775 }
776 return o;
777 }
778
779 /**
780 Get the first argument of the ORDER BY clause for this window
781 if any. "ORDER BY" is not checked in ancestor unlike
782 effective_order_by().
783 Use when the goal is to operate on the set of item clauses for
784 all windows of a query. When interrogating the effective order
785 by for a window (specified for it or inherited from another
786 window) use effective_order_by().
787 */
788 ORDER *first_order_by() const;
789
790 /**
791 Get partition, if any. That is, the partition if any, of the
792 root window. SQL 2011 7.11 GR 1.b.i.4.A-C
793 */
796 const Window *w = m_ancestor;
797 while (w != nullptr) {
798 if (w->m_ancestor == nullptr) {
799 /* root */
800 p = w->m_partition_by;
801 } else {
802 /* See #setup_windows for checking */
803 assert(w->m_partition_by == nullptr);
804 }
805 w = w->m_ancestor;
806 }
807 return p;
808 }
809 /**
810 Get the first argument of the PARTITION clause for this window
811 if any. "PARTITION BY" is not checked in ancestor unlike
812 effective_partition_by().
813 Use when the goal is to operate on the set of item clauses for
814 all windows of a query. When interrogating the effective
815 partition by for a window (specified for it or inherited from
816 another window) use effective_partition_by().
817 */
818 ORDER *first_partition_by() const;
819
820 /**
821 Get the list of functions invoked on this window.
822 */
824
825 /**
826 Concatenation of columns in PARTITION BY and ORDER BY.
827 Columns present in both list (redundancies) are eliminated, while
828 making sure the order of columns in the ORDER BY is maintained
829 in the merged list.
830
831 @param thd Optional. Session state. If not nullptr,
832 initialize the cache.
833
834 @param implicit_grouping Optional. If true, we won't sort (single row
835 result set). Presence implies thd != nullptr for
836 the first call when we lazily set up this
837 information. Succeeding calls return the cached
838 value.
839
840 @returns The start of the concatenated ordering expressions, or nullptr
841 */
842 ORDER *sorting_order(THD *thd = nullptr, bool implicit_grouping = false);
843
844 /**
845 Check that the semantic requirements for window functions over this
846 window are fulfilled, and accumulate evaluation requirements.
847 This is run at resolution.
848 */
849 bool check_window_functions1(THD *thd, Query_block *select);
850 /**
851 Like check_window_functions1() but contains checks which must wait until
852 the start of the execution phase.
853 */
854 bool check_window_functions2(THD *thd);
855
856 /**
857 For RANGE frames we need to do computations involving add/subtract and
858 less than, smaller than. To make this work across types, we construct
859 item trees to do the computations, so we can reuse all the special case
860 handling, e.g. for signed/unsigned int wrap-around, overflow etc.
861 */
862 bool setup_range_expressions(THD *thd);
863
864 /**
865 Return if this window represents an unresolved window reference seen
866 in a window function OVER clause.
867 */
868 bool is_reference() const { return m_is_reference; }
869
870 /**
871 Check if the just read input row marks the start of a new partition.
872 Sets the member variables:
873
874 m_partition_border and m_part_row_number
875
876 */
878
879 /**
880 Reset the current row's ORDER BY expressions when starting a new
881 peer set.
882 */
884
885 /**
886 Determine if the current row is not in the same peer set as the previous
887 row. Used for RANGE frame and implicit RANGE frame (the latter is used by
888 aggregates in the presence of ORDER BY).
889
890 The current row is in the same peer set if all ORDER BY columns
891 have the same value as in the previous row.
892
893 For JSON_OBJECTAGG only the first order by column needs to be
894 compared to check if a row is in peer set.
895
896 @param compare_all_order_by_items If true, compare all the order by items
897 to determine if a row is in peer set.
898 Else, compare only the first order by
899 item to determine peer set.
900
901 @return true if current row is in a new peer set
902 */
903 bool in_new_order_by_peer_set(bool compare_all_order_by_items = true);
904
905 /**
906 While processing buffered rows in RANGE frame mode we, determine
907 if the present row revisited from the buffer is before the row
908 being processed; i.e. the current row.
909
910 @return true if the present row is before the RANGE, i.e. not to
911 be included
912 */
913 bool before_frame() { return before_or_after_frame(true); }
914
915 ///< See before_frame()
916 bool after_frame() { return before_or_after_frame(false); }
917
918 /**
919 Check if we have read all the rows in a partition, possibly
920 having buffered them for further processing
921
922 @returns true if this is the case
923 */
925
926 void save_special_row(uint64 special_rowno, TABLE *t);
927 void restore_special_row(uint64 special_rowno, uchar *record);
928
929 /**
930 Resolve any named window to its definition
931 and update m_window to point to the definition instead
932 */
933 static bool resolve_reference(THD *thd, Item_sum *wf, PT_window **m_window);
934
935 /**
936 Semantic checking of windows. Run at resolution.
937
938 * Process any window inheritance, that is a window, that in its
939 specification refer to another named window.
940
941 Rules:
942 1) There should be no loops
943 2) The inheriting window can not specify partitioning
944 3) The inheriting window can not specify is already specify by
945 an ancestor.
946 4) An ancestor can not specify window framing clause.
947
948 Cf. SQL 2011 7.11 window clause SR 10-11.
949
950 * Check requirements to the window from its using window functions and
951 make a note of those so we know at execution time, for example if we need
952 to buffer rows to process the window functions, whether inversion
953 optimzation will be used for moving frames etc.
954
955 * Prepare the physical ordering lists used by sorting at execution time.
956
957 * Set up cached items for partition determination and for range/peer
958 determination based on order by columns.
959
960 * Check any frame semantics and for RANGE frames, set up bounds computation
961 item trees.
962
963 @param thd The session's execution thread
964 @param select The select for which we are doing windowing
965 @param ref_item_array The base ref items
966 @param tables The list of tables involved
967 @param fields The list of all fields, including hidden ones
968 @param windows The list of windows defined for this select
969
970 @return false if success, true if error
971 */
972 static bool setup_windows1(THD *thd, Query_block *select,
973 Ref_item_array ref_item_array, TABLE_LIST *tables,
975 List<Window> *windows);
976 /**
977 Like setup_windows1() but contains operations which must wait until
978 the start of the execution phase.
979
980 @param thd The session's execution thread
981 @param windows The list of windows defined for this select
982
983 @return false if success, true if error
984 */
985 static bool setup_windows2(THD *thd, List<Window> *windows);
986
987 /**
988 Check window definitions to remove unused windows. We do this
989 only after syntactic and semantic checking for errors has been performed.
990 Eliminate redundant sorts after unused windows are removed.
991
992 @param windows The list of windows defined for this select
993 */
994 static void eliminate_unused_objects(List<Window> *windows);
995
996 /**
997 Resolve and set up the PARTITION BY or an ORDER BY list of a window.
998
999 @param thd The session's execution thread
1000 @param ref_item_array The base ref items
1001 @param tables The list of tables involved
1002 @param fields The list of all fields, including hidden ones
1003 @param o A list of order by expressions
1004 @param partition_order If true, o represent a windowing PARTITION BY,
1005 else it represents a windowing ORDER BY
1006 @returns false if success, true if error
1007 */
1008 bool resolve_window_ordering(THD *thd, Ref_item_array ref_item_array,
1009 TABLE_LIST *tables,
1010 mem_root_deque<Item *> *fields, ORDER *o,
1011 bool partition_order);
1012 /**
1013 Return true if this window's name is not unique in windows
1014 */
1015 bool check_unique_name(const List<Window> &windows);
1016
1017 /**
1018 Specify that this window is to be evaluated after a given
1019 temporary table. This means that all expressions that have been
1020 materialized (as given by items_to_copy) will be replaced with the
1021 given temporary table fields. (If there are multiple materializations,
1022 this function must be called for each of them in order.)
1023
1024 Only the hypergraph join optimizer uses this currently; the old
1025 join optimizer instead uses Item_ref objects that point to the
1026 base slice, which is then replaced at runtime depending on which
1027 temporary table we are to evaluate from.
1028 */
1029 void apply_temp_table(THD *thd, const Func_ptr_array &items_to_copy);
1030
1031 /**
1032 Set up cached items for an partition or an order by list
1033 updating m_partition_items or m_order_by_items respectively.
1034
1035 @param thd The session's execution thread
1036 @param select The select for which we are doing windowing
1037 @param o The list of ordering expressions
1038 @param partition_order If true, o represents a partition order list,
1039 else an ORDER BY list.
1040
1041 @returns false if success, true if error
1042 */
1043 bool setup_ordering_cached_items(THD *thd, Query_block *select,
1044 const PT_order_list *o,
1045 bool partition_order);
1046
1047 /**
1048 Determine if the window had either a partition clause (inclusive) or a
1049 ORDER BY clause, either defined by itself or inherited from another window.
1050
1051 @return true if we have such a clause, which means we need to sort the
1052 input table before evaluating the window functions, unless it has
1053 been made redundant by a previous windowing step, cf.
1054 reorder_and_eliminate_sorts, or due to a single row result set,
1055 cf. Query_block::is_implicitly_grouped().
1056 */
1057 bool needs_sorting() const { return m_sorting_order != nullptr; }
1058
1059 /**
1060 If we cannot compute one of window functions without looking at succeeding
1061 rows, return true, else false.
1062 */
1064
1065 /**
1066 If we cannot compute one of window functions without looking at all
1067 rows in the peerset of the current row, return true, else
1068 false. E.g. CUME_DIST.
1069 */
1070 bool needs_peerset() const { return m_needs_peerset; }
1071
1072 /**
1073 If we cannot compute one of window functions without looking at all
1074 rows in the peerset of the current row in this frame, return true, else
1075 false. E.g. JSON_OBJECTAGG.
1076 */
1078 /**
1079 If we need to read the entire partition before we can evaluate
1080 some window function(s) on this window,
1081 @returns true if that is the case, else false
1082 */
1085 }
1086
1087 /**
1088 Return true if the set of window functions are all ROW unit optimizable.
1089 Only relevant if m_needs_buffering and m_row_optimizable are true.
1090 */
1092
1093 /**
1094 Return true if the set of window functions are all RANGE unit optimizable.
1095 Only relevant if m_needs_buffering and m_range_optimizable are true.
1096 */
1098
1099 /**
1100 Return true if the aggregates are static, i.e. the same aggregate values for
1101 all rows in partition. Only relevant if m_needs_buffering is true.
1102 */
1104
1105 /**
1106 See #m_opt_first_row
1107 */
1108 bool opt_first_row() const { return m_opt_first_row; }
1109
1110 /**
1111 See #m_opt_last_row
1112 */
1113 bool opt_last_row() const { return m_opt_last_row; }
1114
1115 /**
1116 See #m_last
1117 */
1118 bool is_last() const { return m_last; }
1119
1120 /**
1121 An override used by the hypergraph join optimizer only.
1122 */
1123 void set_is_last(bool last) { m_last = last; }
1124
1125 /**
1126 See #m_opt_nth_row
1127 */
1128 const st_nth &opt_nth_row() const { return m_opt_nth_row; }
1129
1130 /**
1131 See #m_opt_lead_lag
1132 */
1133 const st_lead_lag &opt_lead_lag() const { return m_opt_lead_lag; }
1134
1135 /**
1136 Getter for m_frame_buffer_param, q.v.
1137 */
1139
1140 /**
1141 Setter for m_frame_buffer_param, q.v.
1142 */
1144
1145 /**
1146 Getter for m_frame_buffer, q.v.
1147 */
1148 TABLE *frame_buffer() const { return m_frame_buffer; }
1149
1150 /**
1151 Setter for m_frame_buffer, q.v.
1152 */
1154
1155 bool short_circuit() const { return m_short_circuit; }
1158 }
1159
1160 /**
1161 Getter for m_part_row_number, q.v., the current row number within the
1162 partition.
1163 */
1165
1166 /**
1167 Allocate the cache for special rows
1168 @param thd thread handle
1169 @param out_tbl The table where this window function's value is written to
1170 @returns true if error.
1171 */
1172 bool make_special_rows_cache(THD *thd, TABLE *out_tbl);
1173
1174 /**
1175 See #m_last_row_output
1176 */
1178
1179 /**
1180 See #m_last_row_output
1181 */
1183
1184 /**
1185 See #m_rowno_being_visited
1186 */
1188
1189 /**
1190 See #m_rowno_being_visited
1191 */
1193
1194 /**
1195 See #m_last_rowno_in_cache
1196 */
1198
1199 /**
1200 See #m_last_rowno_in_cache
1201 */
1203
1204 /**
1205 See #m_last_rowno_in_range_frame
1206 */
1209 }
1210
1211 /**
1212 See #m_last_rowno_in_range_frame
1213 */
1216 }
1217
1218 /**
1219 See #m_last_rowno_in_peerset
1220 */
1222
1223 /**
1224 See #m_last_rowno_in_peerset
1225 */
1227
1228 /**
1229 See #m_is_last_row_in_peerset_within_frame
1230 */
1233 }
1234
1235 /**
1236 See #m_is_last_row_in_peerset_within_frame
1237 */
1240 }
1241
1242 /**
1243 See #m_do_copy_null
1244 */
1245 bool do_copy_null() const { return m_do_copy_null; }
1246
1247 /**
1248 See #m_do_copy_null
1249 */
1250 void set_do_copy_null(bool b) { m_do_copy_null = b; }
1251
1252 /**
1253 See #m_inverse_aggregation
1254 */
1255 bool do_inverse() const { return m_inverse_aggregation; }
1256
1257 /**
1258 See #m_inverse_aggregation
1259 */
1262 return *this;
1263 }
1264
1265 /**
1266 See #m_aggregates_primed
1267 */
1269
1270 /**
1271 See #m_aggregates_primed
1272 */
1274
1275 /**
1276 See #m_is_last_row_in_frame
1277 */
1279 return m_is_last_row_in_frame || m_query_block->table_list.elements == 0;
1280 }
1281
1282 /**
1283 See #m_is_last_row_in_frame
1284 */
1286
1287 /**
1288 Return the size of the frame in number of rows
1289 @returns frame size
1290 */
1291 // int64 frame_cardinality();
1292
1293 /**
1294 See #m_rowno_in_frame
1295 */
1297
1298 /**
1299 See #m_rowno_in_frame
1300 */
1302 m_rowno_in_frame = rowno;
1303 return *this;
1304 }
1305
1306 /**
1307 See #m_rowno_in_partition
1308 */
1310
1311 /**
1312 See #m_rowno_in_partition
1313 */
1315
1316 /**
1317 See #m_first_rowno_in_range_frame
1318 */
1321 }
1322
1323 /**
1324 See #m_first_rowno_in_range_frame
1325 */
1328 }
1329
1330 /**
1331 See #m_frame_buffer_total_rows
1332 */
1335 }
1336
1337 /**
1338 See #m_frame_buffer_total_rows
1339 */
1341
1342 /**
1343 See #m_frame_buffer_partition_offset
1344 */
1347 }
1348
1349 /**
1350 See #m_frame_buffer_partition_offset
1351 */
1354 }
1355
1356 /**
1357 See #m_row_has_fields_in_out_table
1358 */
1361 }
1362
1363 /**
1364 See #m_row_has_fields_in_out_table
1365 */
1368 }
1369
1370 /**
1371 Free up any resource used to process the window functions of this window,
1372 e.g. temporary files and in-memory data structures. Called when done
1373 with all window processing steps from Query_block::cleanup.
1374 */
1375 void cleanup();
1376
1377 /**
1378 Free structures that were set up during preparation of window functions
1379 */
1380 void destroy();
1381
1382 /**
1383 Reset window state for a new partition.
1384
1385 Reset the temporary storage used for window frames, typically when we find
1386 a new partition. The rows in the buffer are then no longer needed.
1387 */
1389
1390 /**
1391 Reset execution state for next call to JOIN::exec, cf. JOIN::reset,
1392 or using [Buffering]WindowingIterator::Init.
1393 */
1395
1396 /**
1397 Reset execution state for LEAD/LAG for the current row in partition.
1398 */
1399 void reset_lead_lag();
1400
1401 private:
1403
1404 /// Common function for all types of resetting
1406
1407 public:
1408 /**
1409 Reset the execution state for all window functions defined on this window.
1410 */
1411 void reset_all_wf_state();
1412
1413 const char *printable_name() const;
1414
1415 void print(const THD *thd, String *str, enum_query_type qt,
1416 bool expand_definition) const;
1417
1418 bool has_windowing_steps() const;
1419
1420 /**
1421 Compute sorting costs for windowing.
1422
1423 @param cost Cost of sorting result set once
1424 @param windows The set of windows
1425
1426 @returns the aggregated sorting costs of the windowing
1427 */
1428 static double compute_cost(double cost, const List<Window> &windows);
1429
1430 private:
1431 /**
1432 Common implementation of before_frame() and after_frame().
1433 @param before True if 'before' is wanted; false if 'after' is.
1434 */
1435 bool before_or_after_frame(bool before);
1436 void print_frame(const THD *thd, String *str, enum_query_type qt) const;
1437 void print_border(const THD *thd, String *str, PT_border *b,
1438 enum_query_type qt) const;
1439
1440 /**
1441 Reorder windows and eliminate redundant ordering. If a window has the
1442 same ordering requirements as another, we will move them next to each other
1443 in the evaluation sequence, so we can sort only once, i.e. before the
1444 first window step. This allows us to fulfill the guarantee given by
1445 SQL standard when it comes to repeatability of non-deterministic (partially
1446 ordered) result sets for windowing inside a query, cf. #equal_sort.
1447 If more than two have the same ordering, the same applies, we only sort
1448 before the first (sort equivalent) window. The hypergraph optimizer uses
1449 the interesting order framework instead, eliding all sorts eliminated by
1450 this function and possibly more.
1451
1452 Note that we do not merge windows that have the same ordering requirements,
1453 so we may still get the extra materialization and multiple rounds of
1454 buffering. Yet, we should get _correctness_, as long as materialization
1455 preserves row ordering (which it does for all of our supported temporary
1456 table types).
1457
1458 If the result set is implicitly grouped, we also skip any sorting for
1459 windows.
1460
1461 @param windows list of windows
1462 */
1463 static void reorder_and_eliminate_sorts(List<Window> *windows);
1464
1465 /**
1466 Return true of the physical[1] sort orderings for the two windows are the
1467 same, cf. guarantee of
1468 SQL 2014 4.15.15 Windowed tables bullet two: The windowing functions are
1469 computed using the same row ordering if they specify the same ordering.
1470
1471 Collation and null handling is not supported, so moot.
1472
1473 The two other bullet points are also covered by this test.
1474
1475 [1] After concatenating effective PARTITION BY and ORDER BY (including
1476 inheritance) expressions.
1477 */
1478 static bool equal_sort(Window *w1, Window *w2);
1479
1480 /**
1481 Check that a frame border is constant during execution and that it does
1482 not contain subqueries (relevant for INTERVAL only): implementation
1483 limitation.
1484
1485 @param thd Session thread
1486 @param border The border to check
1487
1488 @return false if OK, true if error
1489 */
1490 bool check_constant_bound(THD *thd, PT_border *border);
1491
1492 /**
1493 Check that frame borders are sane; resolution phase.
1494
1495 @param thd Session thread
1496
1497 @returns true if error
1498 */
1499 bool check_border_sanity1(THD *thd);
1500 /**
1501 Like check_border_sanity1() but contains checks which must wait until
1502 the start of the execution phase.
1503
1504 @param thd Session thread
1505
1506 @returns true if error
1507 */
1508 bool check_border_sanity2(THD *thd);
1509};
1510
1511/**
1512 Collects evaluation requirements from a window function,
1513 used by Item_sum::check_wf_semantics and its overrides.
1514*/
1516 /**
1517 Set to true if window function requires row buffering
1518 */
1520 /**
1521 Set to true if we need peerset for evaluation (e.g. CUME_DIST)
1522 */
1524 /**
1525 Set to true if we need last peer for evaluation within a frame
1526 (e.g. JSON_OBJECTAGG)
1527 */
1529 /**
1530 Set to true if we need FIRST_VALUE or optimized MIN/MAX
1531 */
1533 /**
1534 Set to true if we need LAST_VALUE or optimized MIN/MAX
1535 */
1537 Window::st_offset opt_nth_row; ///< Used if we have NTH_VALUE
1538 Window::st_ll_offset opt_ll_row; ///< Used if we have LEAD or LAG
1539 /**
1540 Set to true if we can compute a sliding window by a combination of
1541 undoing the contribution of rows going out of the frame and adding the
1542 contribution of rows coming into the frame. For example, SUM and AVG
1543 allows this, but MAX/MIN do not. Only applicable if the frame has ROW
1544 bounds unit.
1545 */
1547 /**
1548 Similar to row_optimizable but for RANGE frame bounds unit
1549 */
1551
1553 : needs_buffer(false),
1554 needs_peerset(false),
1556 opt_first_row(false),
1557 opt_last_row(false),
1558 row_optimizable(true),
1559 range_optimizable(true) {}
1560};
1561
1562#endif /* WINDOWS_INCLUDED */
A wrapper class which provides array bounds checking.
Definition: sql_array.h:46
This is used for segregating rows in groups (e.g.
Definition: item.h:6182
Definition: item_func.h:93
Definition: item.h:5125
Class Item_sum is the base class used for special expressions that SQL calls 'set functions'.
Definition: item_sum.h:398
Base class that is used to represent any kind of expression in a relational query.
Definition: item.h:802
Definition: sql_list.h:433
A typesafe replacement for DYNAMIC_ARRAY.
Definition: mem_root_array.h:60
A typesafe replacement for DYNAMIC_ARRAY.
Definition: mem_root_array.h:425
Parse tree node for a single of a window extent's borders, cf.
Definition: parse_tree_nodes.h:1246
Parse tree node for a window's frame, cf.
Definition: parse_tree_nodes.h:1325
Definition: parse_tree_nodes.h:213
Parse tree node for a window; just a shallow wrapper for class Window, q.v.
Definition: parse_tree_window.h:38
This class represents a query block, aka a query specification, which is a query consisting of a SELE...
Definition: sql_lex.h:1159
SQL_I_List< TABLE_LIST > table_list
List of tables in FROM clause - use TABLE_LIST::next_local to traverse.
Definition: sql_lex.h:1938
Using this class is fraught with peril, and you need to be very careful when doing so.
Definition: sql_string.h:166
For each client connection we create a separate thread with THD serving as a thread/connection descri...
Definition: sql_class.h:922
Object containing parameters used when creating and using temporary tables.
Definition: temp_table_param.h:94
Represents the (explicit) window of a SQL 2003 section 7.11 <window clause>, or the implicit (inlined...
Definition: window.h:104
static bool equal_sort(Window *w1, Window *w2)
Return true of the physical[1] sort orderings for the two windows are the same, cf.
Definition: window.cc:729
int64 rowno_in_partition() const
See m_rowno_in_partition.
Definition: window.h:1309
Item_string *const m_inherit_from
<existing window name>
Definition: window.h:123
bool m_is_last_row_in_frame
Execution state: the current row is the last row in a window frame For some aggregate functions,...
Definition: window.h:632
bool m_row_optimizable
The functions are optimizable with ROW unit.
Definition: window.h:161
bool check_border_sanity2(THD *thd)
Like check_border_sanity1() but contains checks which must wait until the start of the execution phas...
Definition: window.cc:868
const bool m_is_reference
If true, m_name is an unbound window reference, other fields are unused.
Definition: window.h:128
bool needs_last_peer_in_frame() const
If we cannot compute one of window functions without looking at all rows in the peerset of the curren...
Definition: window.h:1077
void reset_order_by_peer_set()
Reset the current row's ORDER BY expressions when starting a new peer set.
Definition: window.cc:500
int64 last_rowno_in_range_frame() const
See m_last_rowno_in_range_frame.
Definition: window.h:1207
bool before_or_after_frame(bool before)
Common implementation of before_frame() and after_frame().
Definition: window.cc:533
void reset_all_wf_state()
Reset the execution state for all window functions defined on this window.
Definition: window.cc:1499
void apply_temp_table(THD *thd, const Func_ptr_array &items_to_copy)
Specify that this window is to be evaluated after a given temporary table.
Definition: window.cc:1520
bool in_new_order_by_peer_set(bool compare_all_order_by_items=true)
Determine if the current row is not in the same peer set as the previous row.
Definition: window.cc:521
bool opt_last_row() const
See m_opt_last_row.
Definition: window.h:1113
int64 m_rowno_in_partition
Execution state: The row number of the current row being readied for output within the partition.
Definition: window.h:496
void set_last_rowno_in_range_frame(uint64 rno)
See m_last_rowno_in_range_frame.
Definition: window.h:1214
static bool setup_windows1(THD *thd, Query_block *select, Ref_item_array ref_item_array, TABLE_LIST *tables, mem_root_deque< Item * > *fields, List< Window > *windows)
Semantic checking of windows.
Definition: window.cc:1083
void set_def_pos(uint pos)
Definition: window.h:756
Window & set_rowno_in_frame(int64 rowno)
See m_rowno_in_frame.
Definition: window.h:1301
int64 m_first_rowno_in_range_frame
Execution state: the row number of the first row in a frame when evaluating RANGE based frame bounds.
Definition: window.h:589
void reset_partition_state()
Reset window state for a new partition.
Definition: window.h:1388
Item_string * m_name
<window name>
Definition: window.h:116
Frame_buffer_position m_tmp_pos
Sometimes we read one row too many, so that the saved position will be too far out because we subsequ...
Definition: window.h:313
bool static_aggregates() const
Return true if the aggregates are static, i.e.
Definition: window.h:1103
int64 first_rowno_in_range_frame() const
See m_first_rowno_in_range_frame.
Definition: window.h:1326
bool after_frame()
Definition: window.h:916
int64 m_row_has_fields_in_out_table
If >=1: the row with this number (1-based, relative to start of partition) currently has its fields i...
Definition: window.h:421
void copy_pos(Window_retrieve_cached_row_reason from_reason, Window_retrieve_cached_row_reason to_reason)
Copy frame buffer position hint from one to another.
Definition: window.h:339
int64 m_frame_buffer_partition_offset
Execution state: Snapshot of m_frame_buffer_total_rows when we start a new partition,...
Definition: window.h:411
void restore_special_row(uint64 special_rowno, uchar *record)
Restore row special_rowno into record from in-memory copy.
Definition: window_iterators.cc:505
void set_row_has_fields_in_out_table(int64 rowno)
See m_row_has_fields_in_out_table.
Definition: window.h:1366
bool m_needs_peerset
(At least) one window function needs the peer set of the current row to evaluate the wf for the curre...
Definition: window.h:140
ORDER * m_sorting_order
merged partition/order by
Definition: window.h:114
const st_nth & opt_nth_row() const
See m_opt_nth_row.
Definition: window.h:1128
void set_first_rowno_in_range_frame(int64 rowno)
See m_first_rowno_in_range_frame.
Definition: window.h:1319
const Window * m_ancestor
resolved from existing window name
Definition: window.h:236
uint m_def_pos
Position of definition in query's text, 1 for leftmost.
Definition: window.h:122
Temp_table_param * m_frame_buffer_param
Execution state: used iff m_needs_frame_buffering.
Definition: window.h:382
const st_lead_lag & opt_lead_lag() const
See m_opt_lead_lag.
Definition: window.h:1133
bool aggregates_primed() const
See m_aggregates_primed.
Definition: window.h:1268
int64 row_has_fields_in_out_table() const
See m_row_has_fields_in_out_table.
Definition: window.h:1359
int64 m_is_last_row_in_peerset_within_frame
Execution state: used iff m_needs_last_peer_in_frame.
Definition: window.h:454
bool make_special_rows_cache(THD *thd, TABLE *out_tbl)
Allocate the cache for special rows.
Definition: window.cc:1313
size_t m_special_rows_cache_length[FBC_FIRST_KEY - FBC_LAST_KEY+1]
Length of each copy in m_special_rows_cache, in bytes.
Definition: window.h:433
void set_short_circuit(bool short_circuit)
Definition: window.h:1156
const PT_frame * frame() const
Get the frame, if any.
Definition: window.h:761
int64 m_part_row_number
Execution state: the current row number in the current partition.
Definition: window.h:462
PT_order_list *const m_order_by
<window order clause>
Definition: window.h:113
bool check_border_sanity1(THD *thd)
Check that frame borders are sane; resolution phase.
Definition: window.cc:795
int64 rowno_in_frame() const
Return the size of the frame in number of rows.
Definition: window.h:1296
static bool resolve_reference(THD *thd, Item_sum *wf, PT_window **m_window)
Resolve any named window to its definition and update m_window to point to the definition instead.
Definition: window.cc:421
void set_frame_buffer_param(Temp_table_param *p)
Setter for m_frame_buffer_param, q.v.
Definition: window.h:1143
bool short_circuit() const
Definition: window.h:1155
void set_frame_buffer(TABLE *tab)
Setter for m_frame_buffer, q.v.
Definition: window.h:1153
int64 frame_buffer_total_rows() const
See m_frame_buffer_total_rows.
Definition: window.h:1340
const PT_order_list * effective_partition_by() const
Get partition, if any.
Definition: window.h:794
Window(Item_string *name)
Reference to a named window.
Definition: window.h:714
bool needs_buffering() const
If we cannot compute one of window functions without looking at succeeding rows, return true,...
Definition: window.h:1063
int64 m_frame_buffer_total_rows
Execution state: The frame buffer tmp file is not truncated for each new partition.
Definition: window.h:404
bool check_window_functions2(THD *thd)
Like check_window_functions1() but contains checks which must wait until the start of the execution p...
Definition: window.cc:1268
bool m_do_copy_null
Execution state: make frame wf produce a NULL (or 0 depending, e.g.
Definition: window.h:640
bool m_opt_first_row
Window equires re-evaluation of the first row in optimized moving frame mode e.g.
Definition: window.h:182
bool m_inverse_aggregation
Execution state: do inverse, e.g.
Definition: window.h:647
bool m_range_optimizable
The functions are optimizable with RANGE unit.
Definition: window.h:169
bool m_static_aggregates
The aggregates (SUM, etc) can be evaluated once for a partition, since it is static,...
Definition: window.h:176
bool setup_ordering_cached_items(THD *thd, Query_block *select, const PT_order_list *o, bool partition_order)
Set up cached items for an partition or an order by list updating m_partition_items or m_order_by_ite...
Definition: window.cc:637
bool check_window_functions1(THD *thd, Query_block *select)
Check that the semantic requirements for window functions over this window are fulfilled,...
Definition: window.cc:120
Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame)
Unnamed window.
Definition: window.h:721
static void eliminate_unused_objects(List< Window > *windows)
Check window definitions to remove unused windows.
Definition: window.cc:1017
bool check_unique_name(const List< Window > &windows)
Return true if this window's name is not unique in windows.
Definition: window.cc:622
ORDER * first_order_by() const
Get the first argument of the ORDER BY clause for this window if any.
Definition: window.cc:116
bool is_last_row_in_frame() const
See m_is_last_row_in_frame.
Definition: window.h:1278
void set_is_last_row_in_peerset_within_frame(bool value)
See m_is_last_row_in_peerset_within_frame.
Definition: window.h:1238
bool opt_first_row() const
See m_opt_first_row.
Definition: window.h:1108
bool m_needs_partition_cardinality
(At least) one window function needs the cardinality of the partition of the current row to evaluate ...
Definition: window.h:153
void set_name(Item_string *name)
We have a named window.
Definition: window.h:742
uchar * m_special_rows_cache
Holds a fixed number of copies of special rows; each copy can use up to m_special_rows_cache_max_leng...
Definition: window.h:431
static constexpr int FRAME_BUFFER_POSITIONS_CARD
Cardinality of m_frame_buffer_positions if no NTH_VALUE, LEAD/LAG.
Definition: window.h:252
static double compute_cost(double cost, const List< Window > &windows)
Compute sorting costs for windowing.
Definition: window.cc:1513
void set_is_last(bool last)
An override used by the hypergraph join optimizer only.
Definition: window.h:1123
int64 m_rowno_being_visited
Execution state: The number of the row being visited for its contribution to a window function,...
Definition: window.h:484
bool at_partition_border() const
Check if we have read all the rows in a partition, possibly having buffered them for further processi...
Definition: window.h:924
bool m_needs_last_peer_in_frame
(At least) one window function (currently JSON_OBJECTAGG) needs the last peer for the current row to ...
Definition: window.h:147
bool m_last
The last window to be evaluated at execution time.
Definition: window.h:193
const PT_order_list * effective_order_by() const
Get the ORDER BY, if any.
Definition: window.h:768
int64 m_rowno_in_frame
Execution state: the row number of the current row within a frame, cf.
Definition: window.h:490
bool m_aggregates_primed
Execution state: for optimizable aggregates, cf.
Definition: window.h:504
Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame, Item_string *inherit)
Unnamed window based on a named window.
Definition: window.h:728
Mem_root_array< Cached_item * > m_order_by_items
items for the ORDER BY exprs.
Definition: window.h:241
void set_ancestor(Window *a)
After resolving an existing window name reference in a window definition, we set the ancestor pointer...
Definition: window.h:748
void set_last_row_output(int64 rno)
See m_last_row_output.
Definition: window.h:1182
void save_special_row(uint64 special_rowno, TABLE *t)
Save row special_rowno in table t->record[0] to an in-memory copy for later restoration.
Definition: window_iterators.cc:487
int64 is_last_row_in_peerset_within_frame() const
See m_is_last_row_in_peerset_within_frame.
Definition: window.h:1231
bool needs_sorting() const
Determine if the window had either a partition clause (inclusive) or a ORDER BY clause,...
Definition: window.h:1057
st_lead_lag m_opt_lead_lag
Definition: window.h:233
bool before_frame()
While processing buffered rows in RANGE frame mode we, determine if the present row revisited from th...
Definition: window.h:913
void save_pos(Window_retrieve_cached_row_reason reason)
See m_tmp_pos.
Definition: window.h:318
int64 last_row_output() const
See m_last_row_output.
Definition: window.h:1177
bool setup_range_expressions(THD *thd)
For RANGE frames we need to do computations involving add/subtract and less than, smaller than.
Definition: window.cc:239
bool m_short_circuit
Holds whether this window should be “short-circuit”, ie., goes directly to the query output instead o...
Definition: window.h:388
void set_last_rowno_in_peerset(uint64 rno)
See m_last_rowno_in_peerset.
Definition: window.h:1226
Item_string * name() const
Get the name of a window.
Definition: window.h:753
int64 partition_rowno() const
Getter for m_part_row_number, q.v., the current row number within the partition.
Definition: window.h:1164
Query_block * m_query_block
The SELECT the window is on.
Definition: window.h:111
void reset_execution_state(Reset_level level)
Common function for all types of resetting.
Definition: window.cc:1364
ORDER * first_partition_by() const
Get the first argument of the PARTITION clause for this window if any.
Definition: window.cc:112
bool do_inverse() const
See m_inverse_aggregation.
Definition: window.h:1255
void destroy()
Free structures that were set up during preparation of window functions.
Definition: window.cc:1343
void set_rowno_being_visited(int64 rno)
See m_rowno_being_visited.
Definition: window.h:1192
size_t m_special_rows_cache_max_length
Maximum allocated size in m_special_rows_cache.
Definition: window.h:435
TABLE * frame_buffer() const
Getter for m_frame_buffer, q.v.
Definition: window.h:1148
const char * printable_name() const
Definition: window.cc:1492
TABLE * m_frame_buffer
Execution state: used iff m_needs_frame_buffering.
Definition: window.h:394
bool do_copy_null() const
See m_do_copy_null.
Definition: window.h:1245
Window & set_inverse(bool b)
See m_inverse_aggregation.
Definition: window.h:1260
void cleanup()
Free up any resource used to process the window functions of this window, e.g.
Definition: window.cc:1328
bool is_reference() const
Return if this window represents an unresolved window reference seen in a window function OVER clause...
Definition: window.h:868
bool m_partition_border
Execution state: the current row starts a new partition.
Definition: window.h:468
List< Item_sum > & functions()
Get the list of functions invoked on this window.
Definition: window.h:823
int64 m_last_rowno_in_peerset
Execution state: used iff m_needs_peerset.
Definition: window.h:448
void set_last_rowno_in_cache(uint64 rno)
See m_last_rowno_in_cache.
Definition: window.h:1202
void reset_lead_lag()
Reset execution state for LEAD/LAG for the current row in partition.
Definition: window.cc:1355
Temp_table_param * frame_buffer_param() const
Getter for m_frame_buffer_param, q.v.
Definition: window.h:1138
void reset_round()
Reset execution state for next call to JOIN::exec, cf.
Definition: window.h:1394
void set_frame_buffer_partition_offset(int64 offset)
See m_frame_buffer_partition_offset.
Definition: window.h:1345
int64 last_rowno_in_peerset() const
See m_last_rowno_in_peerset.
Definition: window.h:1221
bool optimizable_row_aggregates() const
Return true if the set of window functions are all ROW unit optimizable.
Definition: window.h:1091
Mem_root_array_YY< Frame_buffer_position > m_frame_buffer_positions
Execution state: used iff m_needs_frame_buffering.
Definition: window.h:304
int m_ordering_idx
The logical ordering index (into LogicalOrderings) needed by this window's PARTITION BY and ORDER BY ...
Definition: window.h:565
bool check_constant_bound(THD *thd, PT_border *border)
Check that a frame border is constant during execution and that it does not contain subqueries (relev...
Definition: window.cc:765
bool m_needs_frame_buffering
(At least) one window function needs to buffer frame rows for evaluation i.e.
Definition: window.h:134
bool is_last() const
See m_last.
Definition: window.h:1118
int64 m_last_rowno_in_cache
Execution state: used iff m_needs_frame_buffering.
Definition: window.h:442
Special_keys
Keys for m_special_rows_cache, for special rows (see the comment on m_special_row_cache).
Definition: window.h:363
@ FBC_LAST_KEY
Definition: window.h:374
@ FBC_FIRST_KEY
Definition: window.h:373
@ FBC_FIRST_IN_NEXT_PARTITION
We read an incoming row.
Definition: window.h:370
void print_frame(const THD *thd, String *str, enum_query_type qt) const
Definition: window.cc:1445
bool needs_peerset() const
If we cannot compute one of window functions without looking at all rows in the peerset of the curren...
Definition: window.h:1070
Reset_level
Definition: window.h:1402
@ RL_ROUND
Definition: window.h:1402
@ RL_PARTITION
Definition: window.h:1402
bool m_mark
Used temporarily by the hypergraph join optimizer to mark which windows are referred to by a given or...
Definition: window.h:572
Mem_root_array< Cached_item * > m_partition_items
items for the PARTITION BY columns
Definition: window.h:239
int64 m_last_rowno_in_range_frame
Execution state: used for RANGE bounds frame evaluation for the continued evaluation for current row ...
Definition: window.h:601
int64 m_last_row_output
Execution state: The number, in the current partition, of the last output row, i.e.
Definition: window.h:475
void print_border(const THD *thd, String *str, PT_border *b, enum_query_type qt) const
Definition: window.cc:1414
Bounds_checked_array< Arg_comparator > m_comparators[2]
Definition: window.h:558
uint def_pos() const
Definition: window.h:755
Window(Item_string *name, PT_order_list *part, PT_order_list *ord, PT_frame *frame, bool is_reference, Item_string *inherit)
Generic window constructor, shared.
Definition: window.h:658
PT_frame *const m_frame
<window frame clause>
Definition: window.h:115
void print(const THD *thd, String *str, enum_query_type qt, bool expand_definition) const
Definition: window.cc:1458
int64 rowno_being_visited() const
See m_rowno_being_visited.
Definition: window.h:1187
bool optimizable_range_aggregates() const
Return true if the set of window functions are all RANGE unit optimizable.
Definition: window.h:1097
void check_partition_boundary()
Check if the just read input row marks the start of a new partition.
Definition: window.cc:449
void set_rowno_in_partition(int64 rowno)
See m_rowno_in_partition.
Definition: window.h:1314
bool resolve_window_ordering(THD *thd, Ref_item_array ref_item_array, TABLE_LIST *tables, mem_root_deque< Item * > *fields, ORDER *o, bool partition_order)
Resolve and set up the PARTITION BY or an ORDER BY list of a window.
Definition: window.cc:666
void restore_pos(Window_retrieve_cached_row_reason reason)
See m_tmp_pos.
Definition: window.h:329
bool has_windowing_steps() const
Definition: window.cc:1508
void set_frame_buffer_total_rows(int64 rows)
See m_frame_buffer_total_rows.
Definition: window.h:1333
int64 frame_buffer_partition_offset() const
See m_frame_buffer_partition_offset.
Definition: window.h:1352
void set_is_last_row_in_frame(bool b)
See m_is_last_row_in_frame.
Definition: window.h:1285
void set_aggregates_primed(bool b)
See m_aggregates_primed.
Definition: window.h:1273
st_nth m_opt_nth_row
Window requires re-evaluation of the Nth row in optimized moving frame mode e.g.
Definition: window.h:232
int64 last_rowno_in_cache() const
See m_last_rowno_in_cache.
Definition: window.h:1197
bool needs_partition_cardinality() const
If we need to read the entire partition before we can evaluate some window function(s) on this window...
Definition: window.h:1083
ORDER * sorting_order(THD *thd=nullptr, bool implicit_grouping=false)
Concatenation of columns in PARTITION BY and ORDER BY.
Definition: window.cc:386
List< Item_sum > m_functions
window functions based on 'this'
Definition: window.h:237
void set_do_copy_null(bool b)
See m_do_copy_null.
Definition: window.h:1250
PT_order_list *const m_partition_by
<window partition clause>
Definition: window.h:112
static void reorder_and_eliminate_sorts(List< Window > *windows)
Reorder windows and eliminate redundant ordering.
Definition: window.cc:745
bool m_opt_last_row
Window requires re-evaluation of the last row in optimized moving frame mode e.g.
Definition: window.h:188
static bool setup_windows2(THD *thd, List< Window > *windows)
Like setup_windows1() but contains operations which must wait until the start of the execution phase.
Definition: window.cc:1301
A (partial) implementation of std::deque allocating its blocks on a MEM_ROOT.
Definition: mem_root_deque.h:109
const char * p
Definition: ctype-mb.cc:1236
char * pos
Definition: do_ctype.cc:76
enum_query_type
Query type constants (usable as bitmap flags).
Definition: enum_query_type.h:30
Fido Client Authentication nullptr
Definition: fido_client_plugin.cc:221
Some integer typedefs for easier portability.
#define INT_MIN64
Definition: my_inttypes.h:74
unsigned char uchar
Definition: my_inttypes.h:51
int64_t int64
Definition: my_inttypes.h:67
uint64_t uint64
Definition: my_inttypes.h:68
thread_local MEM_ROOT ** THR_MALLOC
Definition: mysqld.cc:1549
std::string str(const mysqlrouter::ConfigGenerator::Options::Endpoint &ep)
Definition: config_generator.cc:1063
Definition: os0file.h:85
Definition: table.h:280
Definition: table.h:2756
Definition: table.h:1396
Holds information about a position in the buffer frame as stored in a temporary file (cf.
Definition: window.h:261
int64 m_rowno
Definition: window.h:265
uchar * m_position
< The size of the file position is determined by handler::ref_length
Definition: window.h:263
Frame_buffer_position(uchar *position, int64 rowno)
Definition: window.h:266
Definition: window.h:222
Mem_root_array_YY< st_ll_offset > m_offsets
sorted set of LEAD/LAG offsets
Definition: window.h:224
Definition: window.h:207
st_ll_offset()
Definition: window.h:209
int64 m_rowno
negative values is LEAD
Definition: window.h:208
bool operator<(const st_ll_offset &a) const
Used for sorting offsets in ascending order for faster traversal of frame buffer tmp file.
Definition: window.h:214
Definition: window.h:217
Mem_root_array_YY< st_offset > m_offsets
sorted set of NTH_VALUE offsets
Definition: window.h:219
Definition: window.h:196
bool operator<(const st_offset &a) const
Used for sorting offsets in ascending order for faster traversal of frame buffer tmp file.
Definition: window.h:204
st_offset()
Definition: window.h:199
bool m_from_last
Definition: window.h:198
int64 m_rowno
Definition: window.h:197
Collects evaluation requirements from a window function, used by Item_sum::check_wf_semantics and its...
Definition: window.h:1515
bool needs_buffer
Set to true if window function requires row buffering.
Definition: window.h:1519
bool needs_last_peer_in_frame
Set to true if we need last peer for evaluation within a frame (e.g.
Definition: window.h:1528
bool opt_first_row
Set to true if we need FIRST_VALUE or optimized MIN/MAX.
Definition: window.h:1532
bool range_optimizable
Similar to row_optimizable but for RANGE frame bounds unit.
Definition: window.h:1550
Window_evaluation_requirements()
Definition: window.h:1552
Window::st_offset opt_nth_row
Used if we have NTH_VALUE.
Definition: window.h:1537
bool opt_last_row
Set to true if we need LAST_VALUE or optimized MIN/MAX.
Definition: window.h:1536
bool row_optimizable
Set to true if we can compute a sliding window by a combination of undoing the contribution of rows g...
Definition: window.h:1546
bool needs_peerset
Set to true if we need peerset for evaluation (e.g.
Definition: window.h:1523
Window::st_ll_offset opt_ll_row
Used if we have LEAD or LAG.
Definition: window.h:1538
Definition: mi_test3.cc:54
unsigned int uint
Definition: uca-dump.cc:29
constexpr int kMaxWindows
The number of windows is limited to avoid the stack blowing up when constructing iterators recursivel...
Definition: window.h:82
Window_retrieve_cached_row_reason
Position hints for the frame buffer are saved for these kind of row accesses, cf.
Definition: window.h:64