MySQL 8.1.0
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 const 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 const 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 const int from_index = static_cast<int>(from_reason);
342 const 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, readying it for output. That is given by
482 \c m_rowno_in_partition, q.v. Contrast also with \c m_rowno_in_frame
483 which is frame relative.
484 */
486
487 /**
488 Execution state: the row number of the row we are looking at for evaluating
489 its contribution to some window function(s). It is relative to start of
490 the frame and 1-based. It is typically set after fetching a row from the
491 frame buffer using \c bring_back_frame_row and before calling
492 \c copy_funcs. Cf. also \c m_is_last_row_in_frame.
493 */
495
496 /**
497 Execution state: The row number of the current row being readied for
498 output within the partition. 1-based.
499 In \c process_buffered_windowing_record this is known as \c current_row.
500 */
502
503 /**
504 Execution state: for optimizable aggregates, cf. m_row_optimizable and
505 m_range_optimizable, we need to keep track of when we have computed the
506 first aggregate, since aggregates for rows 2..N are computed in an optimized
507 way by inverse aggregation of the row moving out of the frame.
508 */
510
511 /*------------------------------------------------------------------------
512 *
513 * RANGE boundary frame state variables.
514 *
515 *------------------------------------------------------------------------*/
516 public:
517 /*
518 For RANGE bounds, we need to be able to check if a given row is
519 before the lower bound, or after the upper bound, as we don't know
520 ahead of time how many rows to skip (unlike for ROW bounds).
521 Often, the lower and upper bounds are the same, as they are
522 inclusive.
523
524 We solve this by having an array of comparators of the type
525
526 value ⋛ <cache>(ref_value)
527
528 where ⋛ is a three-way comparator, and <cache>(ref_value) is an
529 Item_cache where we can store the value of the reference row
530 before we invoke the comparison. For instance, if we have a
531 row bound such as
532
533 ... OVER (ORDER BY a,b) FROM t1
534
535 we will have an array with the two comparators
536
537 t1.a ⋛ <cache>(a)
538 t1.b ⋛ <cache>(b)
539
540 and when we evaluate the frame bounds for a given row, we insert
541 the reference values in the caches and then do the comparison to
542 figure out if we're before, in or after the bound. As this is a
543 lexicographic comparison, we only need to evaluate the second
544 comparator if the first one returns equality.
545
546 The expressions on the right-hand side can be somewhat more
547 complicated; say that we have a window specification like
548
549 ... OVER (ORDER BY a RANGE BETWEEN 2 PRECEDING AND 3 FOLLOWING)
550
551 In this case, the lower bound and upper bound are different
552 (both arrays will always contain only a single element):
553
554 Lower: t1.a ⋛ <cache>(a) - 2
555 Upper: t1.a ⋛ <cache>(a) + 3
556
557 ie., there is an Item_func_plus or Item_func_minus with some
558 constant expression as the second argument.
559
560 The comparators for the lower bound is stored in [0], and for
561 the upper bound in [1].
562 */
564
565 /**
566 The logical ordering index (into LogicalOrderings) needed by this window's
567 PARTITION BY and ORDER BY clauses together (if any; else, 0). Used only by
568 the hypergraph join optimizer.
569 */
571
572 /**
573 Used temporarily by the hypergraph join optimizer to mark which windows
574 are referred to by a given ordering (so that one doesn't try to satisfy
575 a window's ordering by an ordering referring to that window).
576 */
577 bool m_mark;
578
579 protected:
580 /**
581 Execution state: the row number of the first row in a frame when evaluating
582 RANGE based frame bounds. When using RANGE bounds, we don't know a priori
583 when moving the frame which row number will be the next lower bound, but
584 we know it will have to be a row number higher than the lower bound of
585 the previous frame, since the bounds increase monotonically as long
586 as the frame bounds are static within the query (current limitation).
587 So, it makes sense to remember the first row number in a frame until
588 we have determined the start of the next frame.
589
590 If the frame for the previous current row in the partition was empty (cf.
591 "current_row" in process_buffered_windowing_record), this should point
592 to the next possible frame start. Relative to partition start, 1-based.
593 */
595
596 /**
597 Execution state: used for RANGE bounds frame evaluation
598 for the continued evaluation for current row > 2 in a partition.
599 If the frame for the current row visited (cf "current_row" in
600 process_buffered_windowing_record) was empty, the invariant
601
602 m_last_rowno_in_range_frame < m_first_rowno_in_range_frame
603
604 should hold after the visit. Relative to partition start. 1-based.
605 */
607
608 /**
609 Execution state. Only used for ROWS frame optimized MIN/MAX.
610 The (1-based) number in the partition of first row in the current frame.
611 */
613
614 /*------------------------------------------------------------------------
615 *
616 * Window function special behaviour toggles. These boolean flag influence
617 * the action taken when a window function is evaluated, i.e.
618 *
619 * Item_xxx::val_xxx
620 *
621 * They are set locally just before and after a call to evaluate functions,
622 * i.e.
623 *
624 * w.set_<toggle>(true)
625 * copy_<kind>_window_functions() [see process_buffered_windowing_record]
626 * w.set_<toggle>(false)
627 *
628 * to achieve a special semantic, since we cannot pass down extra parameters.
629 *
630 *------------------------------------------------------------------------*/
631
632 /**
633 Execution state: the current row is the last row in a window frame
634 For some aggregate functions, e.g AVG, we can save computation by not
635 evaluating the entire function value before the last row has been read.
636 For AVG, do the summation for each row in the frame, but the division only
637 for the last row, at which time the result is needed for the wf.
638 Probably only useful for ROW based or static frames.
639 For frame with peer set computation, determining the last row in the
640 peer set ahead of processing is not possible, so we use a pessimistic
641 assumption.
642 */
644
645 /**
646 Execution state: make frame wf produce a NULL (or 0 depending, e.g. if
647 COUNT) value because no rows are available for aggregation: e.g. for first
648 row in partition if frame is ROWS BETWEEN 2 PRECEDING and 1 PRECEDING has
649 no rows for which aggregation can happen
650 */
652
653 /**
654 Execution state: do inverse, e.g. subtract rather than add in aggregates.
655 Used for optimizing computation of sliding frames for eligible aggregates,
656 cf. Item_sum::check_wf_semantics.
657 */
659
660 /*------------------------------------------------------------------------
661 *
662 * Constructors
663 *
664 *------------------------------------------------------------------------*/
665 private:
666 /**
667 Generic window constructor, shared
668 */
670 PT_frame *frame, bool is_reference, Item_string *inherit)
672 m_partition_by(part),
673 m_order_by(ord),
675 m_frame(frame),
676 m_name(name),
677 m_def_pos(0),
678 m_inherit_from(inherit),
681 m_needs_peerset(false),
684 m_row_optimizable(true),
686 m_static_aggregates(false),
687 m_opt_first_row(false),
688 m_opt_last_row(false),
689 m_last(false),
693 m_tmp_pos(nullptr, -1),
704 m_partition_border(true),
709 m_aggregates_primed(false),
713 m_do_copy_null(false),
714 m_inverse_aggregation(false) {
715 m_opt_nth_row.m_offsets.init_empty_const();
716 m_opt_lead_lag.m_offsets.init_empty_const();
717 m_frame_buffer_positions.init_empty_const();
718 }
719
720 public:
721 /**
722 Reference to a named window. This kind is only used before resolution,
723 references to it being replaced by the referenced window object thereafter.
724 */
726 : Window(name, nullptr, nullptr, nullptr, true, nullptr) {}
727
728 /**
729 Unnamed window. If the window turns out to be named, the name will be set
730 later, cf. #set_name().
731 */
732 Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame)
733 : Window(nullptr, partition_by, order_by, frame, false, nullptr) {}
734
735 /**
736 Unnamed window based on a named window. If the window turns out to be
737 named, the name will be set later, cf. #set_name().
738 */
739 Window(PT_order_list *partition_by, PT_order_list *order_by, PT_frame *frame,
740 Item_string *inherit)
741 : Window(nullptr, partition_by, order_by, frame, false, inherit) {}
742
743 /*------------------------------------------------------------------------
744 *
745 * Methods
746 *
747 *------------------------------------------------------------------------*/
748
749 /**
750 We have a named window. Now set its name. Used once, if at all, for a
751 window as part of parsing.
752 */
754
755 /**
756 After resolving an existing window name reference in a window definition,
757 we set the ancestor pointer to easy access later.
758 */
760
761 /**
762 Get the name of a window. Can be empty, cf. #printable_name which is not.
763 */
764 Item_string *name() const { return m_name; }
765
766 uint def_pos() const { return m_def_pos; } ///< @see #m_def_pos
767 void set_def_pos(uint pos) { m_def_pos = pos; } ///< @see #m_def_pos
768
769 /**
770 Get the frame, if any. SQL 2011 7.11 GR 1.b.i.6
771 */
772 const PT_frame *frame() const { return m_frame; }
773
774 /**
775 Get the ORDER BY, if any. That is, the first we find along
776 the ancestor chain. Uniqueness checked in #setup_windows1
777 SQL 2011 7.11 GR 1.b.i.5.A-C
778 */
780 const PT_order_list *o = m_order_by;
781 const Window *w = m_ancestor;
782
783 while (o == nullptr && w != nullptr) {
784 o = w->m_order_by;
785 w = w->m_ancestor;
786 }
787 return o;
788 }
789
790 /**
791 Get the first argument of the ORDER BY clause for this window
792 if any. "ORDER BY" is not checked in ancestor unlike
793 effective_order_by().
794 Use when the goal is to operate on the set of item clauses for
795 all windows of a query. When interrogating the effective order
796 by for a window (specified for it or inherited from another
797 window) use effective_order_by().
798 */
799 ORDER *first_order_by() const;
800
801 /**
802 Get partition, if any. That is, the partition if any, of the
803 root window. SQL 2011 7.11 GR 1.b.i.4.A-C
804 */
807 const Window *w = m_ancestor;
808 while (w != nullptr) {
809 if (w->m_ancestor == nullptr) {
810 /* root */
811 p = w->m_partition_by;
812 } else {
813 /* See #setup_windows for checking */
814 assert(w->m_partition_by == nullptr);
815 }
816 w = w->m_ancestor;
817 }
818 return p;
819 }
820 /**
821 Get the first argument of the PARTITION clause for this window
822 if any. "PARTITION BY" is not checked in ancestor unlike
823 effective_partition_by().
824 Use when the goal is to operate on the set of item clauses for
825 all windows of a query. When interrogating the effective
826 partition by for a window (specified for it or inherited from
827 another window) use effective_partition_by().
828 */
829 ORDER *first_partition_by() const;
830
831 /**
832 Get the list of functions invoked on this window.
833 */
835
836 /**
837 Concatenation of columns in PARTITION BY and ORDER BY.
838 Columns present in both list (redundancies) are eliminated, while
839 making sure the order of columns in the ORDER BY is maintained
840 in the merged list.
841
842 @param thd Optional. Session state. If not nullptr,
843 initialize the cache.
844
845 @param implicit_grouping Optional. If true, we won't sort (single row
846 result set). Presence implies thd != nullptr for
847 the first call when we lazily set up this
848 information. Succeeding calls return the cached
849 value.
850
851 @returns The start of the concatenated ordering expressions, or nullptr
852 */
853 ORDER *sorting_order(THD *thd = nullptr, bool implicit_grouping = false);
854
855 /**
856 Check that the semantic requirements for window functions over this
857 window are fulfilled, and accumulate evaluation requirements.
858 This is run at resolution.
859 */
860 bool check_window_functions1(THD *thd, Query_block *select);
861 /**
862 Like check_window_functions1() but contains checks which must wait until
863 the start of the execution phase.
864 */
865 bool check_window_functions2(THD *thd);
866
867 /**
868 For RANGE frames we need to do computations involving add/subtract and
869 less than, smaller than. To make this work across types, we construct
870 item trees to do the computations, so we can reuse all the special case
871 handling, e.g. for signed/unsigned int wrap-around, overflow etc.
872 */
873 bool setup_range_expressions(THD *thd);
874
875 /**
876 Return if this window represents an unresolved window reference seen
877 in a window function OVER clause.
878 */
879 bool is_reference() const { return m_is_reference; }
880
881 /**
882 Check if the just read input row marks the start of a new partition.
883 Sets the member variables:
884
885 m_partition_border and m_part_row_number
886
887 */
889
890 /**
891 Reset the current row's ORDER BY expressions when starting a new
892 peer set.
893 */
895
896 /**
897 Determine if the current row is not in the same peer set as the previous
898 row. Used for RANGE frame and implicit RANGE frame (the latter is used by
899 aggregates in the presence of ORDER BY).
900
901 The current row is in the same peer set if all ORDER BY columns
902 have the same value as in the previous row.
903
904 For JSON_OBJECTAGG only the first order by column needs to be
905 compared to check if a row is in peer set.
906
907 @param compare_all_order_by_items If true, compare all the order by items
908 to determine if a row is in peer set.
909 Else, compare only the first order by
910 item to determine peer set.
911
912 @return true if current row is in a new peer set
913 */
914 bool in_new_order_by_peer_set(bool compare_all_order_by_items = true);
915
916 /**
917 While processing buffered rows in RANGE frame mode we, determine
918 if the present row revisited from the buffer is before the row
919 being processed; i.e. the current row.
920
921 @return true if the present row is before the RANGE, i.e. not to
922 be included
923 */
924 bool before_frame() { return before_or_after_frame(true); }
925
926 ///< See before_frame()
927 bool after_frame() { return before_or_after_frame(false); }
928
929 /**
930 Check if we have read all the rows in a partition, possibly
931 having buffered them for further processing
932
933 @returns true if this is the case
934 */
936
937 void save_special_row(uint64 special_rowno, TABLE *t);
938 void restore_special_row(uint64 special_rowno, uchar *record);
939
940 /**
941 Resolve any named window to its definition
942 and update m_window to point to the definition instead
943 */
944 static bool resolve_reference(THD *thd, Item_sum *wf, PT_window **m_window);
945
946 /**
947 Semantic checking of windows. Run at resolution.
948
949 * Process any window inheritance, that is a window, that in its
950 specification refer to another named window.
951
952 Rules:
953 1) There should be no loops
954 2) The inheriting window can not specify partitioning
955 3) The inheriting window can not specify is already specify by
956 an ancestor.
957 4) An ancestor can not specify window framing clause.
958
959 Cf. SQL 2011 7.11 window clause SR 10-11.
960
961 * Check requirements to the window from its using window functions and
962 make a note of those so we know at execution time, for example if we need
963 to buffer rows to process the window functions, whether inversion
964 optimzation will be used for moving frames etc.
965
966 * Prepare the physical ordering lists used by sorting at execution time.
967
968 * Set up cached items for partition determination and for range/peer
969 determination based on order by columns.
970
971 * Check any frame semantics and for RANGE frames, set up bounds computation
972 item trees.
973
974 @param thd The session's execution thread
975 @param select The select for which we are doing windowing
976 @param ref_item_array The base ref items
977 @param tables The list of tables involved
978 @param fields The list of all fields, including hidden ones
979 @param windows The list of windows defined for this select
980
981 @return false if success, true if error
982 */
983 static bool setup_windows1(THD *thd, Query_block *select,
984 Ref_item_array ref_item_array, Table_ref *tables,
986 List<Window> *windows);
987 /**
988 Like setup_windows1() but contains operations which must wait until
989 the start of the execution phase.
990
991 @param thd The session's execution thread
992 @param windows The list of windows defined for this select
993
994 @return false if success, true if error
995 */
996 static bool setup_windows2(THD *thd, List<Window> *windows);
997
998 /**
999 Check window definitions to remove unused windows. We do this
1000 only after syntactic and semantic checking for errors has been performed.
1001 Eliminate redundant sorts after unused windows are removed.
1002
1003 @param windows The list of windows defined for this select
1004 */
1005 static void eliminate_unused_objects(List<Window> *windows);
1006
1007 /**
1008 Resolve and set up the PARTITION BY or an ORDER BY list of a window.
1009
1010 @param thd The session's execution thread
1011 @param ref_item_array The base ref items
1012 @param tables The list of tables involved
1013 @param fields The list of all fields, including hidden ones
1014 @param o A list of order by expressions
1015 @param partition_order If true, o represent a windowing PARTITION BY,
1016 else it represents a windowing ORDER BY
1017 @returns false if success, true if error
1018 */
1019 bool resolve_window_ordering(THD *thd, Ref_item_array ref_item_array,
1020 Table_ref *tables,
1021 mem_root_deque<Item *> *fields, ORDER *o,
1022 bool partition_order);
1023 /**
1024 Return true if this window's name is not unique in windows
1025 */
1026 bool check_unique_name(const List<Window> &windows);
1027
1028 /**
1029 Specify that this window is to be evaluated after a given
1030 temporary table. This means that all expressions that have been
1031 materialized (as given by items_to_copy) will be replaced with the
1032 given temporary table fields. (If there are multiple materializations,
1033 this function must be called for each of them in order.)
1034
1035 Only the hypergraph join optimizer uses this currently; the old
1036 join optimizer instead uses Item_ref objects that point to the
1037 base slice, which is then replaced at runtime depending on which
1038 temporary table we are to evaluate from.
1039 */
1040 void apply_temp_table(THD *thd, const Func_ptr_array &items_to_copy);
1041
1042 /**
1043 Set up cached items for an partition or an order by list
1044 updating m_partition_items or m_order_by_items respectively.
1045
1046 @param thd The session's execution thread
1047 @param select The select for which we are doing windowing
1048 @param o The list of ordering expressions
1049 @param partition_order If true, o represents a partition order list,
1050 else an ORDER BY list.
1051
1052 @returns false if success, true if error
1053 */
1054 bool setup_ordering_cached_items(THD *thd, Query_block *select,
1055 const PT_order_list *o,
1056 bool partition_order);
1057
1058 /**
1059 Determine if the window had either a partition clause (inclusive) or a
1060 ORDER BY clause, either defined by itself or inherited from another window.
1061
1062 @return true if we have such a clause, which means we need to sort the
1063 input table before evaluating the window functions, unless it has
1064 been made redundant by a previous windowing step, cf.
1065 reorder_and_eliminate_sorts, or due to a single row result set,
1066 cf. Query_block::is_implicitly_grouped().
1067 */
1068 bool needs_sorting() const { return m_sorting_order != nullptr; }
1069
1070 /**
1071 If we cannot compute one of window functions without looking at succeeding
1072 rows, return true, else false.
1073 */
1075
1076 /**
1077 If we cannot compute one of window functions without looking at all
1078 rows in the peerset of the current row, return true, else
1079 false. E.g. CUME_DIST.
1080 */
1081 bool needs_peerset() const { return m_needs_peerset; }
1082
1083 /**
1084 If we cannot compute one of window functions without looking at all
1085 rows in the peerset of the current row in this frame, return true, else
1086 false. E.g. JSON_OBJECTAGG.
1087 */
1089 /**
1090 If we need to read the entire partition before we can evaluate
1091 some window function(s) on this window,
1092 @returns true if that is the case, else false
1093 */
1096 }
1097
1098 /**
1099 Return true if the set of window functions are all ROW unit optimizable.
1100 Only relevant if m_needs_buffering and m_row_optimizable are true.
1101 */
1103
1104 /**
1105 Return true if the set of window functions are all RANGE unit optimizable.
1106 Only relevant if m_needs_buffering and m_range_optimizable are true.
1107 */
1109
1110 /**
1111 Return true if the aggregates are static, i.e. the same aggregate values for
1112 all rows in partition. Only relevant if m_needs_buffering is true.
1113 */
1115
1116 /**
1117 See #m_opt_first_row
1118 */
1119 bool opt_first_row() const { return m_opt_first_row; }
1120
1121 /**
1122 See #m_opt_last_row
1123 */
1124 bool opt_last_row() const { return m_opt_last_row; }
1125
1126 /**
1127 See #m_last
1128 */
1129 bool is_last() const { return m_last; }
1130
1131 /**
1132 An override used by the hypergraph join optimizer only.
1133 */
1134 void set_is_last(bool last) { m_last = last; }
1135
1136 /**
1137 See #m_opt_nth_row
1138 */
1139 const st_nth &opt_nth_row() const { return m_opt_nth_row; }
1140
1141 /**
1142 See #m_opt_lead_lag
1143 */
1144 const st_lead_lag &opt_lead_lag() const { return m_opt_lead_lag; }
1145
1146 /**
1147 Getter for m_frame_buffer_param, q.v.
1148 */
1150
1151 /**
1152 Setter for m_frame_buffer_param, q.v.
1153 */
1155
1156 /**
1157 Getter for m_frame_buffer, q.v.
1158 */
1159 TABLE *frame_buffer() const { return m_frame_buffer; }
1160
1161 /**
1162 Setter for m_frame_buffer, q.v.
1163 */
1165
1166 bool short_circuit() const { return m_short_circuit; }
1169 }
1170
1171 /**
1172 Getter for m_part_row_number, q.v., the current row number within the
1173 partition.
1174 */
1176
1177 /**
1178 Allocate the cache for special rows
1179 @param thd thread handle
1180 @param out_tbl The table where this window function's value is written to
1181 @returns true if error.
1182 */
1183 bool make_special_rows_cache(THD *thd, TABLE *out_tbl);
1184
1185 /**
1186 See #m_last_row_output
1187 */
1189
1190 /**
1191 See #m_last_row_output
1192 */
1194
1195 /**
1196 See #m_rowno_being_visited
1197 */
1199
1200 /**
1201 See #m_rowno_being_visited
1202 */
1204
1205 /**
1206 See #m_last_rowno_in_cache
1207 */
1209
1210 /**
1211 See #m_last_rowno_in_cache
1212 */
1214
1215 /**
1216 See #m_last_rowno_in_range_frame
1217 */
1220 }
1221
1222 /**
1223 See #m_last_rowno_in_range_frame
1224 */
1227 }
1228
1229 /**
1230 See #m_last_rowno_in_peerset
1231 */
1233
1234 /**
1235 See #m_last_rowno_in_peerset
1236 */
1238
1239 /**
1240 See #m_is_last_row_in_peerset_within_frame
1241 */
1244 }
1245
1246 /**
1247 See #m_is_last_row_in_peerset_within_frame
1248 */
1251 }
1252
1253 /**
1254 See #m_do_copy_null
1255 */
1256 bool do_copy_null() const { return m_do_copy_null; }
1257
1258 /**
1259 See #m_do_copy_null
1260 */
1261 void set_do_copy_null(bool b) { m_do_copy_null = b; }
1262
1263 /**
1264 See #m_inverse_aggregation
1265 */
1266 bool do_inverse() const { return m_inverse_aggregation; }
1267
1268 /**
1269 See #m_inverse_aggregation
1270 */
1273 return *this;
1274 }
1275
1276 /**
1277 See #m_aggregates_primed
1278 */
1280
1281 /**
1282 See #m_aggregates_primed
1283 */
1285
1286 /**
1287 See #m_is_last_row_in_frame
1288 */
1290 return m_is_last_row_in_frame || m_query_block->m_table_list.elements == 0;
1291 }
1292
1293 /**
1294 See #m_is_last_row_in_frame
1295 */
1297
1298 /**
1299 Return the size of the frame in number of rows
1300 @returns frame size
1301 */
1302 // int64 frame_cardinality();
1303
1304 /**
1305 See #m_rowno_in_frame
1306 */
1308
1309 /**
1310 See #m_rowno_in_frame
1311 */
1313 m_rowno_in_frame = rowno;
1314 return *this;
1315 }
1316
1317 /**
1318 See #m_rowno_in_partition
1319 */
1321
1322 /**
1323 See #m_rowno_in_partition
1324 */
1326
1327 /**
1328 See #m_first_rowno_in_rows_frame
1329 */
1332 }
1333
1336 }
1337
1338 /**
1339 See #m_first_rowno_in_range_frame
1340 */
1343 }
1344
1345 /**
1346 See #m_first_rowno_in_range_frame
1347 */
1350 }
1351
1352 /**
1353 See #m_frame_buffer_total_rows
1354 */
1357 }
1358
1359 /**
1360 See #m_frame_buffer_total_rows
1361 */
1363
1364 /**
1365 See #m_frame_buffer_partition_offset
1366 */
1369 }
1370
1371 /**
1372 See #m_frame_buffer_partition_offset
1373 */
1376 }
1377
1378 /**
1379 See #m_row_has_fields_in_out_table
1380 */
1383 }
1384
1385 /**
1386 See #m_row_has_fields_in_out_table
1387 */
1390 }
1391
1392 /**
1393 Free up any resource used to process the window functions of this window,
1394 e.g. temporary files and in-memory data structures. Called when done
1395 with all window processing steps from Query_block::cleanup.
1396 */
1397 void cleanup();
1398
1399 /**
1400 Free structures that were set up during preparation of window functions
1401 */
1402 void destroy();
1403
1404 /**
1405 Reset window state for a new partition.
1406
1407 Reset the temporary storage used for window frames, typically when we find
1408 a new partition. The rows in the buffer are then no longer needed.
1409 */
1411
1412 /**
1413 Reset execution state for next call to JOIN::exec, cf. JOIN::reset,
1414 or using [Buffering]WindowingIterator::Init.
1415 */
1417
1418 /**
1419 Reset execution state for LEAD/LAG for the current row in partition.
1420 */
1421 void reset_lead_lag();
1422
1423 private:
1425
1426 /// Common function for all types of resetting
1428
1429 public:
1430 /**
1431 Reset the execution state for all window functions defined on this window.
1432 */
1433 void reset_all_wf_state();
1434
1435 const char *printable_name() const;
1436
1437 void print(const THD *thd, String *str, enum_query_type qt,
1438 bool expand_definition) const;
1439
1440 bool has_windowing_steps() const;
1441
1442 /**
1443 Compute sorting costs for windowing.
1444
1445 @param cost Cost of sorting result set once
1446 @param windows The set of windows
1447
1448 @returns the aggregated sorting costs of the windowing
1449 */
1450 static double compute_cost(double cost, const List<Window> &windows);
1451
1452 private:
1453 /**
1454 Common implementation of before_frame() and after_frame().
1455 @param before True if 'before' is wanted; false if 'after' is.
1456 */
1457 bool before_or_after_frame(bool before);
1458 void print_frame(const THD *thd, String *str, enum_query_type qt) const;
1459 void print_border(const THD *thd, String *str, PT_border *b,
1460 enum_query_type qt) const;
1461
1462 /**
1463 Reorder windows and eliminate redundant ordering. If a window has the
1464 same ordering requirements as another, we will move them next to each other
1465 in the evaluation sequence, so we can sort only once, i.e. before the
1466 first window step. This allows us to fulfill the guarantee given by
1467 SQL standard when it comes to repeatability of non-deterministic (partially
1468 ordered) result sets for windowing inside a query, cf. #equal_sort.
1469 If more than two have the same ordering, the same applies, we only sort
1470 before the first (sort equivalent) window. The hypergraph optimizer uses
1471 the interesting order framework instead, eliding all sorts eliminated by
1472 this function and possibly more.
1473
1474 Note that we do not merge windows that have the same ordering requirements,
1475 so we may still get the extra materialization and multiple rounds of
1476 buffering. Yet, we should get _correctness_, as long as materialization
1477 preserves row ordering (which it does for all of our supported temporary
1478 table types).
1479
1480 If the result set is implicitly grouped, we also skip any sorting for
1481 windows.
1482
1483 @param windows list of windows
1484 */
1485 static void reorder_and_eliminate_sorts(List<Window> *windows);
1486
1487 /**
1488 Return true of the physical[1] sort orderings for the two windows are the
1489 same, cf. guarantee of
1490 SQL 2014 4.15.15 Windowed tables bullet two: The windowing functions are
1491 computed using the same row ordering if they specify the same ordering.
1492
1493 Collation and null handling is not supported, so moot.
1494
1495 The two other bullet points are also covered by this test.
1496
1497 [1] After concatenating effective PARTITION BY and ORDER BY (including
1498 inheritance) expressions.
1499 */
1500 static bool equal_sort(Window *w1, Window *w2);
1501
1502 /**
1503 Check that a frame border is constant during execution and that it does
1504 not contain subqueries (relevant for INTERVAL only): implementation
1505 limitation.
1506
1507 @param thd Session thread
1508 @param border The border to check
1509
1510 @return false if OK, true if error
1511 */
1512 bool check_constant_bound(THD *thd, PT_border *border);
1513
1514 /**
1515 Check that frame borders are sane; resolution phase.
1516
1517 @param thd Session thread
1518
1519 @returns true if error
1520 */
1521 bool check_border_sanity1(THD *thd);
1522 /**
1523 Like check_border_sanity1() but contains checks which must wait until
1524 the start of the execution phase.
1525
1526 @param thd Session thread
1527
1528 @returns true if error
1529 */
1530 bool check_border_sanity2(THD *thd);
1531};
1532
1533/**
1534 Collects evaluation requirements from a window function,
1535 used by Item_sum::check_wf_semantics and its overrides.
1536*/
1538 /**
1539 Set to true if window function requires row buffering
1540 */
1542 /**
1543 Set to true if we need peerset for evaluation (e.g. CUME_DIST)
1544 */
1546 /**
1547 Set to true if we need last peer for evaluation within a frame
1548 (e.g. JSON_OBJECTAGG)
1549 */
1551 /**
1552 Set to true if we need FIRST_VALUE or optimized MIN/MAX
1553 */
1555 /**
1556 Set to true if we need LAST_VALUE or optimized MIN/MAX
1557 */
1559 Window::st_offset opt_nth_row; ///< Used if we have NTH_VALUE
1560 Window::st_ll_offset opt_ll_row; ///< Used if we have LEAD or LAG
1561 /**
1562 Set to true if we can compute a sliding window by a combination of
1563 undoing the contribution of rows going out of the frame and adding the
1564 contribution of rows coming into the frame. For example, SUM and AVG
1565 allows this, but MAX/MIN do not. Only applicable if the frame has ROW
1566 bounds unit.
1567 */
1569 /**
1570 Similar to row_optimizable but for RANGE frame bounds unit
1571 */
1573
1575 : needs_buffer(false),
1576 needs_peerset(false),
1578 opt_first_row(false),
1579 opt_last_row(false),
1580 row_optimizable(true),
1581 range_optimizable(true) {}
1582};
1583
1584#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:6408
Definition: item_func.h:101
Definition: item.h:5327
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:853
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:1351
Parse tree node for a window's frame, cf.
Definition: parse_tree_nodes.h:1439
Definition: parse_tree_nodes.h:231
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:1162
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:1907
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:2800
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:735
int64 rowno_in_partition() const
See m_rowno_in_partition.
Definition: window.h:1320
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:643
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:874
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:1088
void reset_order_by_peer_set()
Reset the current row's ORDER BY expressions when starting a new peer set.
Definition: window.cc:506
int64 last_rowno_in_range_frame() const
See m_last_rowno_in_range_frame.
Definition: window.h:1218
bool before_or_after_frame(bool before)
Common implementation of before_frame() and after_frame().
Definition: window.cc:539
void reset_all_wf_state()
Reset the execution state for all window functions defined on this window.
Definition: window.cc:1506
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:1527
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:527
bool opt_last_row() const
See m_opt_last_row.
Definition: window.h:1124
int64 m_rowno_in_partition
Execution state: The row number of the current row being readied for output within the partition.
Definition: window.h:501
void set_last_rowno_in_range_frame(uint64 rno)
See m_last_rowno_in_range_frame.
Definition: window.h:1225
void set_def_pos(uint pos)
Definition: window.h:767
Window & set_rowno_in_frame(int64 rowno)
See m_rowno_in_frame.
Definition: window.h:1312
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:594
void reset_partition_state()
Reset window state for a new partition.
Definition: window.h:1410
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:1114
int64 first_rowno_in_range_frame() const
See m_first_rowno_in_range_frame.
Definition: window.h:1348
bool after_frame()
Definition: window.h:927
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:672
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:1388
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:1139
void set_first_rowno_in_range_frame(int64 rowno)
See m_first_rowno_in_range_frame.
Definition: window.h:1341
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:1144
bool aggregates_primed() const
See m_aggregates_primed.
Definition: window.h:1279
int64 row_has_fields_in_out_table() const
See m_row_has_fields_in_out_table.
Definition: window.h:1381
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:1319
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:1167
const PT_frame * frame() const
Get the frame, if any.
Definition: window.h:772
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:801
int64 rowno_in_frame() const
Return the size of the frame in number of rows.
Definition: window.h:1307
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:427
void set_frame_buffer_param(Temp_table_param *p)
Setter for m_frame_buffer_param, q.v.
Definition: window.h:1154
bool short_circuit() const
Definition: window.h:1166
void set_frame_buffer(TABLE *tab)
Setter for m_frame_buffer, q.v.
Definition: window.h:1164
int64 frame_buffer_total_rows() const
See m_frame_buffer_total_rows.
Definition: window.h:1362
const PT_order_list * effective_partition_by() const
Get partition, if any.
Definition: window.h:805
Window(Item_string *name)
Reference to a named window.
Definition: window.h:725
bool needs_buffering() const
If we cannot compute one of window functions without looking at succeeding rows, return true,...
Definition: window.h:1074
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:1274
bool m_do_copy_null
Execution state: make frame wf produce a NULL (or 0 depending, e.g.
Definition: window.h:651
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:658
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:643
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:732
static void eliminate_unused_objects(List< Window > *windows)
Check window definitions to remove unused windows.
Definition: window.cc:1023
bool check_unique_name(const List< Window > &windows)
Return true if this window's name is not unique in windows.
Definition: window.cc:628
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:1289
void set_is_last_row_in_peerset_within_frame(bool value)
See m_is_last_row_in_peerset_within_frame.
Definition: window.h:1249
bool opt_first_row() const
See m_opt_first_row.
Definition: window.h:1119
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:753
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:1520
void set_is_last(bool last)
An override used by the hypergraph join optimizer only.
Definition: window.h:1134
int64 m_rowno_being_visited
Execution state: The number of the row being visited for its contribution to a window function,...
Definition: window.h:485
int64 first_rowno_in_rows_frame() const
Definition: window.h:1334
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:935
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:1330
const PT_order_list * effective_order_by() const
Get the ORDER BY, if any.
Definition: window.h:779
int64 m_rowno_in_frame
Execution state: the row number of the row we are looking at for evaluating its contribution to some ...
Definition: window.h:494
bool m_aggregates_primed
Execution state: for optimizable aggregates, cf.
Definition: window.h:509
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:739
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:759
void set_last_row_output(int64 rno)
See m_last_row_output.
Definition: window.h:1193
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:1242
bool needs_sorting() const
Determine if the window had either a partition clause (inclusive) or a ORDER BY clause,...
Definition: window.h:1068
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:924
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:1188
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:1237
Item_string * name() const
Get the name of a window.
Definition: window.h:764
int64 partition_rowno() const
Getter for m_part_row_number, q.v., the current row number within the partition.
Definition: window.h:1175
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:1370
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:1266
int64 m_first_rowno_in_rows_frame
Execution state.
Definition: window.h:612
void destroy()
Free structures that were set up during preparation of window functions.
Definition: window.cc:1349
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:1089
void set_rowno_being_visited(int64 rno)
See m_rowno_being_visited.
Definition: window.h:1203
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:1159
const char * printable_name() const
Definition: window.cc:1499
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:1256
Window & set_inverse(bool b)
See m_inverse_aggregation.
Definition: window.h:1271
void cleanup()
Free up any resource used to process the window functions of this window, e.g.
Definition: window.cc:1334
bool is_reference() const
Return if this window represents an unresolved window reference seen in a window function OVER clause...
Definition: window.h:879
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:834
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:1213
void reset_lead_lag()
Reset execution state for LEAD/LAG for the current row in partition.
Definition: window.cc:1361
Temp_table_param * frame_buffer_param() const
Getter for m_frame_buffer_param, q.v.
Definition: window.h:1149
void reset_round()
Reset execution state for next call to JOIN::exec, cf.
Definition: window.h:1416
void set_frame_buffer_partition_offset(int64 offset)
See m_frame_buffer_partition_offset.
Definition: window.h:1367
int64 last_rowno_in_peerset() const
See m_last_rowno_in_peerset.
Definition: window.h:1232
bool optimizable_row_aggregates() const
Return true if the set of window functions are all ROW unit optimizable.
Definition: window.h:1102
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:570
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:771
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:1129
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:1452
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:1081
Reset_level
Definition: window.h:1424
@ RL_ROUND
Definition: window.h:1424
@ RL_PARTITION
Definition: window.h:1424
bool m_mark
Used temporarily by the hypergraph join optimizer to mark which windows are referred to by a given or...
Definition: window.h:577
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:606
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:1421
Bounds_checked_array< Arg_comparator > m_comparators[2]
Definition: window.h:563
uint def_pos() const
Definition: window.h:766
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:669
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:1465
int64 rowno_being_visited() const
See m_rowno_being_visited.
Definition: window.h:1198
bool optimizable_range_aggregates() const
Return true if the set of window functions are all RANGE unit optimizable.
Definition: window.h:1108
void check_partition_boundary()
Check if the just read input row marks the start of a new partition.
Definition: window.cc:455
void set_rowno_in_partition(int64 rowno)
See m_rowno_in_partition.
Definition: window.h:1325
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:1515
void set_frame_buffer_total_rows(int64 rows)
See m_frame_buffer_total_rows.
Definition: window.h:1355
int64 frame_buffer_partition_offset() const
See m_frame_buffer_partition_offset.
Definition: window.h:1374
void set_is_last_row_in_frame(bool b)
See m_is_last_row_in_frame.
Definition: window.h:1296
void set_aggregates_primed(bool b)
See m_aggregates_primed.
Definition: window.h:1284
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:1208
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:1094
ORDER * sorting_order(THD *thd=nullptr, bool implicit_grouping=false)
Concatenation of columns in PARTITION BY and ORDER BY.
Definition: window.cc:392
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:1261
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:751
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:1307
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:1234
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:1567
static int record
Definition: mysqltest.cc:194
std::string str(const mysqlrouter::ConfigGenerator::Options::Endpoint &ep)
Definition: config_generator.cc:1063
Definition: os0file.h:85
Definition: table.h:283
Definition: table.h:1394
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:1537
bool needs_buffer
Set to true if window function requires row buffering.
Definition: window.h:1541
bool needs_last_peer_in_frame
Set to true if we need last peer for evaluation within a frame (e.g.
Definition: window.h:1550
bool opt_first_row
Set to true if we need FIRST_VALUE or optimized MIN/MAX.
Definition: window.h:1554
bool range_optimizable
Similar to row_optimizable but for RANGE frame bounds unit.
Definition: window.h:1572
Window_evaluation_requirements()
Definition: window.h:1574
Window::st_offset opt_nth_row
Used if we have NTH_VALUE.
Definition: window.h:1559
bool opt_last_row
Set to true if we need LAST_VALUE or optimized MIN/MAX.
Definition: window.h:1558
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:1568
bool needs_peerset
Set to true if we need peerset for evaluation (e.g.
Definition: window.h:1545
Window::st_ll_offset opt_ll_row
Used if we have LEAD or LAG.
Definition: window.h:1560
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