MySQL 8.0.32
Source Code Documentation
window.h
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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 Execution state. Only used for ROWS frame optimized MIN/MAX.
605 The (1-based) number in the partition of first row in the current frame.
606 */
608
609 /*------------------------------------------------------------------------
610 *
611 * Window function special behaviour toggles. These boolean flag influence
612 * the action taken when a window function is evaluated, i.e.
613 *
614 * Item_xxx::val_xxx
615 *
616 * They are set locally just before and after a call to evaluate functions,
617 * i.e.
618 *
619 * w.set_<toggle>(true)
620 * copy_<kind>_window_functions() [see process_buffered_windowing_record]
621 * w.set_<toggle>(false)
622 *
623 * to achieve a special semantic, since we cannot pass down extra parameters.
624 *
625 *------------------------------------------------------------------------*/
626
627 /**
628 Execution state: the current row is the last row in a window frame
629 For some aggregate functions, e.g AVG, we can save computation by not
630 evaluating the entire function value before the last row has been read.
631 For AVG, do the summation for each row in the frame, but the division only
632 for the last row, at which time the result is needed for the wf.
633 Probably only useful for ROW based or static frames.
634 For frame with peer set computation, determining the last row in the
635 peer set ahead of processing is not possible, so we use a pessimistic
636 assumption.
637 */
639
640 /**
641 Execution state: make frame wf produce a NULL (or 0 depending, e.g. if
642 COUNT) value because no rows are available for aggregation: e.g. for first
643 row in partition if frame is ROWS BETWEEN 2 PRECEDING and 1 PRECEDING has
644 no rows for which aggregation can happen
645 */
647
648 /**
649 Execution state: do inverse, e.g. subtract rather than add in aggregates.
650 Used for optimizing computation of sliding frames for eligible aggregates,
651 cf. Item_sum::check_wf_semantics.
652 */
654
655 /*------------------------------------------------------------------------
656 *
657 * Constructors
658 *
659 *------------------------------------------------------------------------*/
660 private:
661 /**
662 Generic window constructor, shared
663 */
665 PT_frame *frame, bool is_reference, Item_string *inherit)
667 m_partition_by(part),
668 m_order_by(ord),
670 m_frame(frame),
671 m_name(name),
672 m_def_pos(0),
673 m_inherit_from(inherit),
676 m_needs_peerset(false),
679 m_row_optimizable(true),
681 m_static_aggregates(false),
682 m_opt_first_row(false),
683 m_opt_last_row(false),
684 m_last(false),
688 m_tmp_pos(nullptr, -1),
699 m_partition_border(true),
704 m_aggregates_primed(false),
708 m_do_copy_null(false),
709 m_inverse_aggregation(false) {
710 m_opt_nth_row.m_offsets.init_empty_const();
711 m_opt_lead_lag.m_offsets.init_empty_const();
712 m_frame_buffer_positions.init_empty_const();
713 }
714
715 public:
716 /**
717 Reference to a named window. This kind is only used before resolution,
718 references to it being replaced by the referenced window object thereafter.
719 */
721 : Window(name, nullptr, nullptr, nullptr, true, nullptr) {}
722
723 /**
724 Unnamed window. If the window turns out to be named, the name will be set
725 later, cf. #set_name().
726 */
727 Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame)
728 : Window(nullptr, partition_by, order_by, frame, false, nullptr) {}
729
730 /**
731 Unnamed window based on a named window. If the window turns out to be
732 named, the name will be set later, cf. #set_name().
733 */
734 Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame,
735 Item_string *inherit)
736 : Window(nullptr, partition_by, order_by, frame, false, inherit) {}
737
738 /*------------------------------------------------------------------------
739 *
740 * Methods
741 *
742 *------------------------------------------------------------------------*/
743
744 /**
745 We have a named window. Now set its name. Used once, if at all, for a
746 window as part of parsing.
747 */
749
750 /**
751 After resolving an existing window name reference in a window definition,
752 we set the ancestor pointer to easy access later.
753 */
755
756 /**
757 Get the name of a window. Can be empty, cf. #printable_name which is not.
758 */
759 Item_string *name() const { return m_name; }
760
761 uint def_pos() const { return m_def_pos; } ///< @see #m_def_pos
762 void set_def_pos(uint pos) { m_def_pos = pos; } ///< @see #m_def_pos
763
764 /**
765 Get the frame, if any. SQL 2011 7.11 GR 1.b.i.6
766 */
767 const PT_frame *frame() const { return m_frame; }
768
769 /**
770 Get the ORDER BY, if any. That is, the first we find along
771 the ancestor chain. Uniqueness checked in #setup_windows1
772 SQL 2011 7.11 GR 1.b.i.5.A-C
773 */
775 const PT_order_list *o = m_order_by;
776 const Window *w = m_ancestor;
777
778 while (o == nullptr && w != nullptr) {
779 o = w->m_order_by;
780 w = w->m_ancestor;
781 }
782 return o;
783 }
784
785 /**
786 Get the first argument of the ORDER BY clause for this window
787 if any. "ORDER BY" is not checked in ancestor unlike
788 effective_order_by().
789 Use when the goal is to operate on the set of item clauses for
790 all windows of a query. When interrogating the effective order
791 by for a window (specified for it or inherited from another
792 window) use effective_order_by().
793 */
794 ORDER *first_order_by() const;
795
796 /**
797 Get partition, if any. That is, the partition if any, of the
798 root window. SQL 2011 7.11 GR 1.b.i.4.A-C
799 */
802 const Window *w = m_ancestor;
803 while (w != nullptr) {
804 if (w->m_ancestor == nullptr) {
805 /* root */
806 p = w->m_partition_by;
807 } else {
808 /* See #setup_windows for checking */
809 assert(w->m_partition_by == nullptr);
810 }
811 w = w->m_ancestor;
812 }
813 return p;
814 }
815 /**
816 Get the first argument of the PARTITION clause for this window
817 if any. "PARTITION BY" is not checked in ancestor unlike
818 effective_partition_by().
819 Use when the goal is to operate on the set of item clauses for
820 all windows of a query. When interrogating the effective
821 partition by for a window (specified for it or inherited from
822 another window) use effective_partition_by().
823 */
824 ORDER *first_partition_by() const;
825
826 /**
827 Get the list of functions invoked on this window.
828 */
830
831 /**
832 Concatenation of columns in PARTITION BY and ORDER BY.
833 Columns present in both list (redundancies) are eliminated, while
834 making sure the order of columns in the ORDER BY is maintained
835 in the merged list.
836
837 @param thd Optional. Session state. If not nullptr,
838 initialize the cache.
839
840 @param implicit_grouping Optional. If true, we won't sort (single row
841 result set). Presence implies thd != nullptr for
842 the first call when we lazily set up this
843 information. Succeeding calls return the cached
844 value.
845
846 @returns The start of the concatenated ordering expressions, or nullptr
847 */
848 ORDER *sorting_order(THD *thd = nullptr, bool implicit_grouping = false);
849
850 /**
851 Check that the semantic requirements for window functions over this
852 window are fulfilled, and accumulate evaluation requirements.
853 This is run at resolution.
854 */
855 bool check_window_functions1(THD *thd, Query_block *select);
856 /**
857 Like check_window_functions1() but contains checks which must wait until
858 the start of the execution phase.
859 */
860 bool check_window_functions2(THD *thd);
861
862 /**
863 For RANGE frames we need to do computations involving add/subtract and
864 less than, smaller than. To make this work across types, we construct
865 item trees to do the computations, so we can reuse all the special case
866 handling, e.g. for signed/unsigned int wrap-around, overflow etc.
867 */
868 bool setup_range_expressions(THD *thd);
869
870 /**
871 Return if this window represents an unresolved window reference seen
872 in a window function OVER clause.
873 */
874 bool is_reference() const { return m_is_reference; }
875
876 /**
877 Check if the just read input row marks the start of a new partition.
878 Sets the member variables:
879
880 m_partition_border and m_part_row_number
881
882 */
884
885 /**
886 Reset the current row's ORDER BY expressions when starting a new
887 peer set.
888 */
890
891 /**
892 Determine if the current row is not in the same peer set as the previous
893 row. Used for RANGE frame and implicit RANGE frame (the latter is used by
894 aggregates in the presence of ORDER BY).
895
896 The current row is in the same peer set if all ORDER BY columns
897 have the same value as in the previous row.
898
899 For JSON_OBJECTAGG only the first order by column needs to be
900 compared to check if a row is in peer set.
901
902 @param compare_all_order_by_items If true, compare all the order by items
903 to determine if a row is in peer set.
904 Else, compare only the first order by
905 item to determine peer set.
906
907 @return true if current row is in a new peer set
908 */
909 bool in_new_order_by_peer_set(bool compare_all_order_by_items = true);
910
911 /**
912 While processing buffered rows in RANGE frame mode we, determine
913 if the present row revisited from the buffer is before the row
914 being processed; i.e. the current row.
915
916 @return true if the present row is before the RANGE, i.e. not to
917 be included
918 */
919 bool before_frame() { return before_or_after_frame(true); }
920
921 ///< See before_frame()
922 bool after_frame() { return before_or_after_frame(false); }
923
924 /**
925 Check if we have read all the rows in a partition, possibly
926 having buffered them for further processing
927
928 @returns true if this is the case
929 */
931
932 void save_special_row(uint64 special_rowno, TABLE *t);
933 void restore_special_row(uint64 special_rowno, uchar *record);
934
935 /**
936 Resolve any named window to its definition
937 and update m_window to point to the definition instead
938 */
939 static bool resolve_reference(THD *thd, Item_sum *wf, PT_window **m_window);
940
941 /**
942 Semantic checking of windows. Run at resolution.
943
944 * Process any window inheritance, that is a window, that in its
945 specification refer to another named window.
946
947 Rules:
948 1) There should be no loops
949 2) The inheriting window can not specify partitioning
950 3) The inheriting window can not specify is already specify by
951 an ancestor.
952 4) An ancestor can not specify window framing clause.
953
954 Cf. SQL 2011 7.11 window clause SR 10-11.
955
956 * Check requirements to the window from its using window functions and
957 make a note of those so we know at execution time, for example if we need
958 to buffer rows to process the window functions, whether inversion
959 optimzation will be used for moving frames etc.
960
961 * Prepare the physical ordering lists used by sorting at execution time.
962
963 * Set up cached items for partition determination and for range/peer
964 determination based on order by columns.
965
966 * Check any frame semantics and for RANGE frames, set up bounds computation
967 item trees.
968
969 @param thd The session's execution thread
970 @param select The select for which we are doing windowing
971 @param ref_item_array The base ref items
972 @param tables The list of tables involved
973 @param fields The list of all fields, including hidden ones
974 @param windows The list of windows defined for this select
975
976 @return false if success, true if error
977 */
978 static bool setup_windows1(THD *thd, Query_block *select,
979 Ref_item_array ref_item_array, Table_ref *tables,
981 List<Window> *windows);
982 /**
983 Like setup_windows1() but contains operations which must wait until
984 the start of the execution phase.
985
986 @param thd The session's execution thread
987 @param windows The list of windows defined for this select
988
989 @return false if success, true if error
990 */
991 static bool setup_windows2(THD *thd, List<Window> *windows);
992
993 /**
994 Check window definitions to remove unused windows. We do this
995 only after syntactic and semantic checking for errors has been performed.
996 Eliminate redundant sorts after unused windows are removed.
997
998 @param windows The list of windows defined for this select
999 */
1000 static void eliminate_unused_objects(List<Window> *windows);
1001
1002 /**
1003 Resolve and set up the PARTITION BY or an ORDER BY list of a window.
1004
1005 @param thd The session's execution thread
1006 @param ref_item_array The base ref items
1007 @param tables The list of tables involved
1008 @param fields The list of all fields, including hidden ones
1009 @param o A list of order by expressions
1010 @param partition_order If true, o represent a windowing PARTITION BY,
1011 else it represents a windowing ORDER BY
1012 @returns false if success, true if error
1013 */
1014 bool resolve_window_ordering(THD *thd, Ref_item_array ref_item_array,
1015 Table_ref *tables,
1016 mem_root_deque<Item *> *fields, ORDER *o,
1017 bool partition_order);
1018 /**
1019 Return true if this window's name is not unique in windows
1020 */
1021 bool check_unique_name(const List<Window> &windows);
1022
1023 /**
1024 Specify that this window is to be evaluated after a given
1025 temporary table. This means that all expressions that have been
1026 materialized (as given by items_to_copy) will be replaced with the
1027 given temporary table fields. (If there are multiple materializations,
1028 this function must be called for each of them in order.)
1029
1030 Only the hypergraph join optimizer uses this currently; the old
1031 join optimizer instead uses Item_ref objects that point to the
1032 base slice, which is then replaced at runtime depending on which
1033 temporary table we are to evaluate from.
1034 */
1035 void apply_temp_table(THD *thd, const Func_ptr_array &items_to_copy);
1036
1037 /**
1038 Set up cached items for an partition or an order by list
1039 updating m_partition_items or m_order_by_items respectively.
1040
1041 @param thd The session's execution thread
1042 @param select The select for which we are doing windowing
1043 @param o The list of ordering expressions
1044 @param partition_order If true, o represents a partition order list,
1045 else an ORDER BY list.
1046
1047 @returns false if success, true if error
1048 */
1049 bool setup_ordering_cached_items(THD *thd, Query_block *select,
1050 const PT_order_list *o,
1051 bool partition_order);
1052
1053 /**
1054 Determine if the window had either a partition clause (inclusive) or a
1055 ORDER BY clause, either defined by itself or inherited from another window.
1056
1057 @return true if we have such a clause, which means we need to sort the
1058 input table before evaluating the window functions, unless it has
1059 been made redundant by a previous windowing step, cf.
1060 reorder_and_eliminate_sorts, or due to a single row result set,
1061 cf. Query_block::is_implicitly_grouped().
1062 */
1063 bool needs_sorting() const { return m_sorting_order != nullptr; }
1064
1065 /**
1066 If we cannot compute one of window functions without looking at succeeding
1067 rows, return true, else false.
1068 */
1070
1071 /**
1072 If we cannot compute one of window functions without looking at all
1073 rows in the peerset of the current row, return true, else
1074 false. E.g. CUME_DIST.
1075 */
1076 bool needs_peerset() const { return m_needs_peerset; }
1077
1078 /**
1079 If we cannot compute one of window functions without looking at all
1080 rows in the peerset of the current row in this frame, return true, else
1081 false. E.g. JSON_OBJECTAGG.
1082 */
1084 /**
1085 If we need to read the entire partition before we can evaluate
1086 some window function(s) on this window,
1087 @returns true if that is the case, else false
1088 */
1091 }
1092
1093 /**
1094 Return true if the set of window functions are all ROW unit optimizable.
1095 Only relevant if m_needs_buffering and m_row_optimizable are true.
1096 */
1098
1099 /**
1100 Return true if the set of window functions are all RANGE unit optimizable.
1101 Only relevant if m_needs_buffering and m_range_optimizable are true.
1102 */
1104
1105 /**
1106 Return true if the aggregates are static, i.e. the same aggregate values for
1107 all rows in partition. Only relevant if m_needs_buffering is true.
1108 */
1110
1111 /**
1112 See #m_opt_first_row
1113 */
1114 bool opt_first_row() const { return m_opt_first_row; }
1115
1116 /**
1117 See #m_opt_last_row
1118 */
1119 bool opt_last_row() const { return m_opt_last_row; }
1120
1121 /**
1122 See #m_last
1123 */
1124 bool is_last() const { return m_last; }
1125
1126 /**
1127 An override used by the hypergraph join optimizer only.
1128 */
1129 void set_is_last(bool last) { m_last = last; }
1130
1131 /**
1132 See #m_opt_nth_row
1133 */
1134 const st_nth &opt_nth_row() const { return m_opt_nth_row; }
1135
1136 /**
1137 See #m_opt_lead_lag
1138 */
1139 const st_lead_lag &opt_lead_lag() const { return m_opt_lead_lag; }
1140
1141 /**
1142 Getter for m_frame_buffer_param, q.v.
1143 */
1145
1146 /**
1147 Setter for m_frame_buffer_param, q.v.
1148 */
1150
1151 /**
1152 Getter for m_frame_buffer, q.v.
1153 */
1154 TABLE *frame_buffer() const { return m_frame_buffer; }
1155
1156 /**
1157 Setter for m_frame_buffer, q.v.
1158 */
1160
1161 bool short_circuit() const { return m_short_circuit; }
1164 }
1165
1166 /**
1167 Getter for m_part_row_number, q.v., the current row number within the
1168 partition.
1169 */
1171
1172 /**
1173 Allocate the cache for special rows
1174 @param thd thread handle
1175 @param out_tbl The table where this window function's value is written to
1176 @returns true if error.
1177 */
1178 bool make_special_rows_cache(THD *thd, TABLE *out_tbl);
1179
1180 /**
1181 See #m_last_row_output
1182 */
1184
1185 /**
1186 See #m_last_row_output
1187 */
1189
1190 /**
1191 See #m_rowno_being_visited
1192 */
1194
1195 /**
1196 See #m_rowno_being_visited
1197 */
1199
1200 /**
1201 See #m_last_rowno_in_cache
1202 */
1204
1205 /**
1206 See #m_last_rowno_in_cache
1207 */
1209
1210 /**
1211 See #m_last_rowno_in_range_frame
1212 */
1215 }
1216
1217 /**
1218 See #m_last_rowno_in_range_frame
1219 */
1222 }
1223
1224 /**
1225 See #m_last_rowno_in_peerset
1226 */
1228
1229 /**
1230 See #m_last_rowno_in_peerset
1231 */
1233
1234 /**
1235 See #m_is_last_row_in_peerset_within_frame
1236 */
1239 }
1240
1241 /**
1242 See #m_is_last_row_in_peerset_within_frame
1243 */
1246 }
1247
1248 /**
1249 See #m_do_copy_null
1250 */
1251 bool do_copy_null() const { return m_do_copy_null; }
1252
1253 /**
1254 See #m_do_copy_null
1255 */
1256 void set_do_copy_null(bool b) { m_do_copy_null = b; }
1257
1258 /**
1259 See #m_inverse_aggregation
1260 */
1261 bool do_inverse() const { return m_inverse_aggregation; }
1262
1263 /**
1264 See #m_inverse_aggregation
1265 */
1268 return *this;
1269 }
1270
1271 /**
1272 See #m_aggregates_primed
1273 */
1275
1276 /**
1277 See #m_aggregates_primed
1278 */
1280
1281 /**
1282 See #m_is_last_row_in_frame
1283 */
1285 return m_is_last_row_in_frame || m_query_block->m_table_list.elements == 0;
1286 }
1287
1288 /**
1289 See #m_is_last_row_in_frame
1290 */
1292
1293 /**
1294 Return the size of the frame in number of rows
1295 @returns frame size
1296 */
1297 // int64 frame_cardinality();
1298
1299 /**
1300 See #m_rowno_in_frame
1301 */
1303
1304 /**
1305 See #m_rowno_in_frame
1306 */
1308 m_rowno_in_frame = rowno;
1309 return *this;
1310 }
1311
1312 /**
1313 See #m_rowno_in_partition
1314 */
1316
1317 /**
1318 See #m_rowno_in_partition
1319 */
1321
1322 /**
1323 See #m_first_rowno_in_rows_frame
1324 */
1327 }
1328
1331 }
1332
1333 /**
1334 See #m_first_rowno_in_range_frame
1335 */
1338 }
1339
1340 /**
1341 See #m_first_rowno_in_range_frame
1342 */
1345 }
1346
1347 /**
1348 See #m_frame_buffer_total_rows
1349 */
1352 }
1353
1354 /**
1355 See #m_frame_buffer_total_rows
1356 */
1358
1359 /**
1360 See #m_frame_buffer_partition_offset
1361 */
1364 }
1365
1366 /**
1367 See #m_frame_buffer_partition_offset
1368 */
1371 }
1372
1373 /**
1374 See #m_row_has_fields_in_out_table
1375 */
1378 }
1379
1380 /**
1381 See #m_row_has_fields_in_out_table
1382 */
1385 }
1386
1387 /**
1388 Free up any resource used to process the window functions of this window,
1389 e.g. temporary files and in-memory data structures. Called when done
1390 with all window processing steps from Query_block::cleanup.
1391 */
1392 void cleanup();
1393
1394 /**
1395 Free structures that were set up during preparation of window functions
1396 */
1397 void destroy();
1398
1399 /**
1400 Reset window state for a new partition.
1401
1402 Reset the temporary storage used for window frames, typically when we find
1403 a new partition. The rows in the buffer are then no longer needed.
1404 */
1406
1407 /**
1408 Reset execution state for next call to JOIN::exec, cf. JOIN::reset,
1409 or using [Buffering]WindowingIterator::Init.
1410 */
1412
1413 /**
1414 Reset execution state for LEAD/LAG for the current row in partition.
1415 */
1416 void reset_lead_lag();
1417
1418 private:
1420
1421 /// Common function for all types of resetting
1423
1424 public:
1425 /**
1426 Reset the execution state for all window functions defined on this window.
1427 */
1428 void reset_all_wf_state();
1429
1430 const char *printable_name() const;
1431
1432 void print(const THD *thd, String *str, enum_query_type qt,
1433 bool expand_definition) const;
1434
1435 bool has_windowing_steps() const;
1436
1437 /**
1438 Compute sorting costs for windowing.
1439
1440 @param cost Cost of sorting result set once
1441 @param windows The set of windows
1442
1443 @returns the aggregated sorting costs of the windowing
1444 */
1445 static double compute_cost(double cost, const List<Window> &windows);
1446
1447 private:
1448 /**
1449 Common implementation of before_frame() and after_frame().
1450 @param before True if 'before' is wanted; false if 'after' is.
1451 */
1452 bool before_or_after_frame(bool before);
1453 void print_frame(const THD *thd, String *str, enum_query_type qt) const;
1454 void print_border(const THD *thd, String *str, PT_border *b,
1455 enum_query_type qt) const;
1456
1457 /**
1458 Reorder windows and eliminate redundant ordering. If a window has the
1459 same ordering requirements as another, we will move them next to each other
1460 in the evaluation sequence, so we can sort only once, i.e. before the
1461 first window step. This allows us to fulfill the guarantee given by
1462 SQL standard when it comes to repeatability of non-deterministic (partially
1463 ordered) result sets for windowing inside a query, cf. #equal_sort.
1464 If more than two have the same ordering, the same applies, we only sort
1465 before the first (sort equivalent) window. The hypergraph optimizer uses
1466 the interesting order framework instead, eliding all sorts eliminated by
1467 this function and possibly more.
1468
1469 Note that we do not merge windows that have the same ordering requirements,
1470 so we may still get the extra materialization and multiple rounds of
1471 buffering. Yet, we should get _correctness_, as long as materialization
1472 preserves row ordering (which it does for all of our supported temporary
1473 table types).
1474
1475 If the result set is implicitly grouped, we also skip any sorting for
1476 windows.
1477
1478 @param windows list of windows
1479 */
1480 static void reorder_and_eliminate_sorts(List<Window> *windows);
1481
1482 /**
1483 Return true of the physical[1] sort orderings for the two windows are the
1484 same, cf. guarantee of
1485 SQL 2014 4.15.15 Windowed tables bullet two: The windowing functions are
1486 computed using the same row ordering if they specify the same ordering.
1487
1488 Collation and null handling is not supported, so moot.
1489
1490 The two other bullet points are also covered by this test.
1491
1492 [1] After concatenating effective PARTITION BY and ORDER BY (including
1493 inheritance) expressions.
1494 */
1495 static bool equal_sort(Window *w1, Window *w2);
1496
1497 /**
1498 Check that a frame border is constant during execution and that it does
1499 not contain subqueries (relevant for INTERVAL only): implementation
1500 limitation.
1501
1502 @param thd Session thread
1503 @param border The border to check
1504
1505 @return false if OK, true if error
1506 */
1507 bool check_constant_bound(THD *thd, PT_border *border);
1508
1509 /**
1510 Check that frame borders are sane; resolution phase.
1511
1512 @param thd Session thread
1513
1514 @returns true if error
1515 */
1516 bool check_border_sanity1(THD *thd);
1517 /**
1518 Like check_border_sanity1() but contains checks which must wait until
1519 the start of the execution phase.
1520
1521 @param thd Session thread
1522
1523 @returns true if error
1524 */
1525 bool check_border_sanity2(THD *thd);
1526};
1527
1528/**
1529 Collects evaluation requirements from a window function,
1530 used by Item_sum::check_wf_semantics and its overrides.
1531*/
1533 /**
1534 Set to true if window function requires row buffering
1535 */
1537 /**
1538 Set to true if we need peerset for evaluation (e.g. CUME_DIST)
1539 */
1541 /**
1542 Set to true if we need last peer for evaluation within a frame
1543 (e.g. JSON_OBJECTAGG)
1544 */
1546 /**
1547 Set to true if we need FIRST_VALUE or optimized MIN/MAX
1548 */
1550 /**
1551 Set to true if we need LAST_VALUE or optimized MIN/MAX
1552 */
1554 Window::st_offset opt_nth_row; ///< Used if we have NTH_VALUE
1555 Window::st_ll_offset opt_ll_row; ///< Used if we have LEAD or LAG
1556 /**
1557 Set to true if we can compute a sliding window by a combination of
1558 undoing the contribution of rows going out of the frame and adding the
1559 contribution of rows coming into the frame. For example, SUM and AVG
1560 allows this, but MAX/MIN do not. Only applicable if the frame has ROW
1561 bounds unit.
1562 */
1564 /**
1565 Similar to row_optimizable but for RANGE frame bounds unit
1566 */
1568
1570 : needs_buffer(false),
1571 needs_peerset(false),
1573 opt_first_row(false),
1574 opt_last_row(false),
1575 row_optimizable(true),
1576 range_optimizable(true) {}
1577};
1578
1579#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:6274
Definition: item_func.h:93
Definition: item.h:5195
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:850
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:1242
Parse tree node for a window's frame, cf.
Definition: parse_tree_nodes.h:1321
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:1153
SQL_I_List< Table_ref > m_table_list
List of tables in FROM clause - use Table_ref::next_local to traverse.
Definition: sql_lex.h:1891
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_lexer_thd.h:33
Definition: table.h:2755
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:1315
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:638
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:1083
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:1213
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:1500
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:1521
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:1119
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:1220
void set_def_pos(uint pos)
Definition: window.h:762
Window & set_rowno_in_frame(int64 rowno)
See m_rowno_in_frame.
Definition: window.h:1307
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:1405
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:1109
int64 first_rowno_in_range_frame() const
See m_first_rowno_in_range_frame.
Definition: window.h:1343
bool after_frame()
Definition: window.h:922
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
bool resolve_window_ordering(THD *thd, Ref_item_array ref_item_array, Table_ref *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_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:1383
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:1134
void set_first_rowno_in_range_frame(int64 rowno)
See m_first_rowno_in_range_frame.
Definition: window.h:1336
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:1139
bool aggregates_primed() const
See m_aggregates_primed.
Definition: window.h:1274
int64 row_has_fields_in_out_table() const
See m_row_has_fields_in_out_table.
Definition: window.h:1376
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:1162
const PT_frame * frame() const
Get the frame, if any.
Definition: window.h:767
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:1302
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:1149
bool short_circuit() const
Definition: window.h:1161
void set_frame_buffer(TABLE *tab)
Setter for m_frame_buffer, q.v.
Definition: window.h:1159
int64 frame_buffer_total_rows() const
See m_frame_buffer_total_rows.
Definition: window.h:1357
const PT_order_list * effective_partition_by() const
Get partition, if any.
Definition: window.h:800
Window(Item_string *name)
Reference to a named window.
Definition: window.h:720
bool needs_buffering() const
If we cannot compute one of window functions without looking at succeeding rows, return true,...
Definition: window.h:1069
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:646
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:653
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:727
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:1284
void set_is_last_row_in_peerset_within_frame(bool value)
See m_is_last_row_in_peerset_within_frame.
Definition: window.h:1244
bool opt_first_row() const
See m_opt_first_row.
Definition: window.h:1114
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:748
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:1514
void set_is_last(bool last)
An override used by the hypergraph join optimizer only.
Definition: window.h:1129
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
int64 first_rowno_in_rows_frame() const
Definition: window.h:1329
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:930
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
void set_first_rowno_in_rows_frame(int64 rowno)
See m_first_rowno_in_rows_frame.
Definition: window.h:1325
const PT_order_list * effective_order_by() const
Get the ORDER BY, if any.
Definition: window.h:774
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:734
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:754
void set_last_row_output(int64 rno)
See m_last_row_output.
Definition: window.h:1188
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:1237
bool needs_sorting() const
Determine if the window had either a partition clause (inclusive) or a ORDER BY clause,...
Definition: window.h:1063
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:919
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:1183
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:1232
Item_string * name() const
Get the name of a window.
Definition: window.h:759
int64 partition_rowno() const
Getter for m_part_row_number, q.v., the current row number within the partition.
Definition: window.h:1170
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:1261
int64 m_first_rowno_in_rows_frame
Execution state.
Definition: window.h:607
void destroy()
Free structures that were set up during preparation of window functions.
Definition: window.cc:1343
static bool setup_windows1(THD *thd, Query_block *select, Ref_item_array ref_item_array, Table_ref *tables, mem_root_deque< Item * > *fields, List< Window > *windows)
Semantic checking of windows.
Definition: window.cc:1083
void set_rowno_being_visited(int64 rno)
See m_rowno_being_visited.
Definition: window.h:1198
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:1154
const char * printable_name() const
Definition: window.cc:1493
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:1251
Window & set_inverse(bool b)
See m_inverse_aggregation.
Definition: window.h:1266
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:874
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:829
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:1208
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:1144
void reset_round()
Reset execution state for next call to JOIN::exec, cf.
Definition: window.h:1411
void set_frame_buffer_partition_offset(int64 offset)
See m_frame_buffer_partition_offset.
Definition: window.h:1362
int64 last_rowno_in_peerset() const
See m_last_rowno_in_peerset.
Definition: window.h:1227
bool optimizable_row_aggregates() const
Return true if the set of window functions are all ROW unit optimizable.
Definition: window.h:1097
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:1124
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:1446
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:1076
Reset_level
Definition: window.h:1419
@ RL_ROUND
Definition: window.h:1419
@ RL_PARTITION
Definition: window.h:1419
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:1415
Bounds_checked_array< Arg_comparator > m_comparators[2]
Definition: window.h:558
uint def_pos() const
Definition: window.h:761
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:664
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:1459
int64 rowno_being_visited() const
See m_rowno_being_visited.
Definition: window.h:1193
bool optimizable_range_aggregates() const
Return true if the set of window functions are all RANGE unit optimizable.
Definition: window.h:1103
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:1320
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:1509
void set_frame_buffer_total_rows(int64 rows)
See m_frame_buffer_total_rows.
Definition: window.h:1350
int64 frame_buffer_partition_offset() const
See m_frame_buffer_partition_offset.
Definition: window.h:1369
void set_is_last_row_in_frame(bool b)
See m_is_last_row_in_frame.
Definition: window.h:1291
void set_aggregates_primed(bool b)
See m_aggregates_primed.
Definition: window.h:1279
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:1203
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:1089
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:1256
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
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:1551
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:1395
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:1532
bool needs_buffer
Set to true if window function requires row buffering.
Definition: window.h:1536
bool needs_last_peer_in_frame
Set to true if we need last peer for evaluation within a frame (e.g.
Definition: window.h:1545
bool opt_first_row
Set to true if we need FIRST_VALUE or optimized MIN/MAX.
Definition: window.h:1549
bool range_optimizable
Similar to row_optimizable but for RANGE frame bounds unit.
Definition: window.h:1567
Window_evaluation_requirements()
Definition: window.h:1569
Window::st_offset opt_nth_row
Used if we have NTH_VALUE.
Definition: window.h:1554
bool opt_last_row
Set to true if we need LAST_VALUE or optimized MIN/MAX.
Definition: window.h:1553
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:1563
bool needs_peerset
Set to true if we need peerset for evaluation (e.g.
Definition: window.h:1540
Window::st_ll_offset opt_ll_row
Used if we have LEAD or LAG.
Definition: window.h:1555
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