-
Notifications
You must be signed in to change notification settings - Fork 5.6k
/
queryoptimizer.cpp
1301 lines (1166 loc) · 49.3 KB
/
queryoptimizer.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
// @file queryoptimizer.cpp
/**
* Copyright (C) 2008 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "pch.h"
#include "db.h"
#include "btree.h"
#include "pdfile.h"
#include "queryoptimizer.h"
#include "cmdline.h"
#include "clientcursor.h"
//#define DEBUGQO(x) cout << x << endl;
#define DEBUGQO(x)
namespace mongo {
void checkTableScanAllowed( const char * ns ) {
if ( ! cmdLine.noTableScan )
return;
if ( strstr( ns , ".system." ) ||
strstr( ns , "local." ) )
return;
if ( ! nsdetails( ns ) )
return;
uassert( 10111 , (string)"table scans not allowed:" + ns , ! cmdLine.noTableScan );
}
double elementDirection( const BSONElement &e ) {
if ( e.isNumber() )
return e.number();
return 1;
}
QueryPlan::QueryPlan(
NamespaceDetails *d, int idxNo,
const FieldRangeSetPair &frsp, const FieldRangeSetPair *originalFrsp, const BSONObj &originalQuery, const BSONObj &order, bool mustAssertOnYieldFailure, const BSONObj &startKey, const BSONObj &endKey , string special ) :
_d(d), _idxNo(idxNo),
_frs( frsp.frsForIndex( _d, _idxNo ) ),
_frsMulti( frsp.frsForIndex( _d, -1 ) ),
_originalQuery( originalQuery ),
_order( order ),
_index( 0 ),
_optimal( false ),
_scanAndOrderRequired( true ),
_exactKeyMatch( false ),
_direction( 0 ),
_endKeyInclusive( endKey.isEmpty() ),
_unhelpful( false ),
_impossible( false ),
_special( special ),
_type(0),
_startOrEndSpec( !startKey.isEmpty() || !endKey.isEmpty() ),
_mustAssertOnYieldFailure( mustAssertOnYieldFailure ) {
BSONObj idxKey = _idxNo < 0 ? BSONObj() : d->idx( _idxNo ).keyPattern();
if ( !_frs.matchPossibleForIndex( idxKey ) ) {
_impossible = true;
_scanAndOrderRequired = false;
return;
}
if ( willScanTable() ) {
if ( _order.isEmpty() || !strcmp( _order.firstElementFieldName(), "$natural" ) )
_scanAndOrderRequired = false;
return;
}
_index = &d->idx(_idxNo);
// If the parsing or index indicates this is a special query, don't continue the processing
if ( _special.size() ||
( _index->getSpec().getType() && _index->getSpec().getType()->suitability( originalQuery, order ) != USELESS ) ) {
if( _special.size() ) _optimal = true;
_type = _index->getSpec().getType();
if( !_special.size() ) _special = _index->getSpec().getType()->getPlugin()->getName();
massert( 13040 , (string)"no type for special: " + _special , _type );
// hopefully safe to use original query in these contexts - don't think we can mix special with $or clause separation yet
_scanAndOrderRequired = _type->scanAndOrderRequired( _originalQuery , order );
return;
}
const IndexSpec &idxSpec = _index->getSpec();
BSONObjIterator o( order );
BSONObjIterator k( idxKey );
if ( !o.moreWithEOO() )
_scanAndOrderRequired = false;
while( o.moreWithEOO() ) {
BSONElement oe = o.next();
if ( oe.eoo() ) {
_scanAndOrderRequired = false;
break;
}
if ( !k.moreWithEOO() )
break;
BSONElement ke;
while( 1 ) {
ke = k.next();
if ( ke.eoo() )
goto doneCheckOrder;
if ( strcmp( oe.fieldName(), ke.fieldName() ) == 0 )
break;
if ( !_frs.range( ke.fieldName() ).equality() )
goto doneCheckOrder;
}
int d = elementDirection( oe ) == elementDirection( ke ) ? 1 : -1;
if ( _direction == 0 )
_direction = d;
else if ( _direction != d )
break;
}
doneCheckOrder:
if ( _scanAndOrderRequired )
_direction = 0;
BSONObjIterator i( idxKey );
int exactIndexedQueryCount = 0;
int optimalIndexedQueryCount = 0;
bool stillOptimalIndexedQueryCount = true;
set<string> orderFieldsUnindexed;
order.getFieldNames( orderFieldsUnindexed );
while( i.moreWithEOO() ) {
BSONElement e = i.next();
if ( e.eoo() )
break;
const FieldRange &fr = _frs.range( e.fieldName() );
if ( stillOptimalIndexedQueryCount ) {
if ( fr.nontrivial() )
++optimalIndexedQueryCount;
if ( !fr.equality() )
stillOptimalIndexedQueryCount = false;
}
else {
if ( fr.nontrivial() )
optimalIndexedQueryCount = -1;
}
if ( fr.equality() ) {
BSONElement e = fr.max();
if ( !e.isNumber() && !e.mayEncapsulate() && e.type() != RegEx )
++exactIndexedQueryCount;
}
orderFieldsUnindexed.erase( e.fieldName() );
}
if ( !_scanAndOrderRequired &&
( optimalIndexedQueryCount == _frs.nNontrivialRanges() ) )
_optimal = true;
if ( exactIndexedQueryCount == _frs.nNontrivialRanges() &&
orderFieldsUnindexed.size() == 0 &&
exactIndexedQueryCount == idxKey.nFields() &&
exactIndexedQueryCount == _originalQuery.nFields() ) {
_exactKeyMatch = true;
}
_frv.reset( new FieldRangeVector( _frs, idxSpec, _direction ) );
if ( originalFrsp ) {
_originalFrv.reset( new FieldRangeVector( originalFrsp->frsForIndex( _d, _idxNo ), idxSpec, _direction ) );
}
else {
_originalFrv = _frv;
}
if ( _startOrEndSpec ) {
BSONObj newStart, newEnd;
if ( !startKey.isEmpty() )
_startKey = startKey;
else
_startKey = _frv->startKey();
if ( !endKey.isEmpty() )
_endKey = endKey;
else
_endKey = _frv->endKey();
}
if ( ( _scanAndOrderRequired || _order.isEmpty() ) &&
!_frs.range( idxKey.firstElementFieldName() ).nontrivial() ) {
_unhelpful = true;
}
}
shared_ptr<Cursor> QueryPlan::newCursor( const DiskLoc &startLoc , int numWanted ) const {
if ( _type ) {
// hopefully safe to use original query in these contexts - don't think we can mix type with $or clause separation yet
return _type->newCursor( _originalQuery , _order , numWanted );
}
if ( _impossible ) {
// TODO We might want to allow this dummy table scan even in no table
// scan mode, since it won't scan anything.
if ( _frs.nNontrivialRanges() )
checkTableScanAllowed( _frs.ns() );
return shared_ptr<Cursor>( new BasicCursor( DiskLoc() ) );
}
if ( willScanTable() ) {
if ( _frs.nNontrivialRanges() ) {
checkTableScanAllowed( _frs.ns() );
// if we are doing a table scan on _id
// and its a capped collection
// we disallow as its a common user error
// .system. and local collections are exempt
if ( _d && _d->capped && _frs.range( "_id" ).nontrivial() ) {
if ( cc().isSyncThread() ||
str::contains( _frs.ns() , ".system." ) ||
str::startsWith( _frs.ns() , "local." ) ) {
// ok
}
else {
warning() << "_id query on capped collection without an _id index, performance will be poor collection: " << _frs.ns() << endl;
//uassert( 14820, str::stream() << "doing _id query on a capped collection without an index is not allowed: " << _frs.ns() ,
}
}
}
return findTableScan( _frs.ns(), _order, startLoc );
}
massert( 10363 , "newCursor() with start location not implemented for indexed plans", startLoc.isNull() );
if ( _startOrEndSpec ) {
// we are sure to spec _endKeyInclusive
return shared_ptr<Cursor>( BtreeCursor::make( _d, _idxNo, *_index, _startKey, _endKey, _endKeyInclusive, _direction >= 0 ? 1 : -1 ) );
}
else if ( _index->getSpec().getType() ) {
return shared_ptr<Cursor>( BtreeCursor::make( _d, _idxNo, *_index, _frv->startKey(), _frv->endKey(), true, _direction >= 0 ? 1 : -1 ) );
}
else {
return shared_ptr<Cursor>( BtreeCursor::make( _d, _idxNo, *_index, _frv, _direction >= 0 ? 1 : -1 ) );
}
}
shared_ptr<Cursor> QueryPlan::newReverseCursor() const {
if ( willScanTable() ) {
int orderSpec = _order.getIntField( "$natural" );
if ( orderSpec == INT_MIN )
orderSpec = 1;
return findTableScan( _frs.ns(), BSON( "$natural" << -orderSpec ) );
}
massert( 10364 , "newReverseCursor() not implemented for indexed plans", false );
return shared_ptr<Cursor>();
}
BSONObj QueryPlan::indexKey() const {
if ( !_index )
return BSON( "$natural" << 1 );
return _index->keyPattern();
}
void QueryPlan::registerSelf( long long nScanned ) const {
// FIXME SERVER-2864 Otherwise no query pattern can be generated.
if ( _frs.matchPossible() ) {
SimpleMutex::scoped_lock lk(NamespaceDetailsTransient::_qcMutex);
NamespaceDetailsTransient::get_inlock( ns() ).registerIndexForPattern( _frs.pattern( _order ), indexKey(), nScanned );
}
}
/**
* @return a copy of the inheriting class, which will be run with its own
* query plan. If multiple plan sets are required for an $or query, the
* QueryOp of the winning plan from a given set will be cloned to generate
* QueryOps for the subsequent plan set. This function should only be called
* after the query op has completed executing.
*/
QueryOp *QueryOp::createChild() {
if( _orConstraint.get() ) {
_matcher->advanceOrClause( _orConstraint );
_orConstraint.reset();
}
QueryOp *ret = _createChild();
ret->_oldMatcher = _matcher;
return ret;
}
bool QueryPlan::isMultiKey() const {
if ( _idxNo < 0 )
return false;
return _d->isMultikey( _idxNo );
}
void QueryOp::init() {
if ( _oldMatcher.get() ) {
_matcher.reset( _oldMatcher->nextClauseMatcher( qp().indexKey() ) );
}
else {
_matcher.reset( new CoveredIndexMatcher( qp().originalQuery(), qp().indexKey(), alwaysUseRecord() ) );
}
_init();
}
QueryPlanSet::QueryPlanSet( const char *ns, auto_ptr<FieldRangeSetPair> frsp, auto_ptr<FieldRangeSetPair> originalFrsp, const BSONObj &originalQuery, const BSONObj &order, bool mustAssertOnYieldFailure, const BSONElement *hint, bool honorRecordedPlan, const BSONObj &min, const BSONObj &max, bool bestGuessOnly, bool mayYield ) :
_ns(ns),
_originalQuery( originalQuery ),
_frsp( frsp ),
_originalFrsp( originalFrsp ),
_mayRecordPlan( true ),
_usingPrerecordedPlan( false ),
_hint( BSONObj() ),
_order( order.getOwned() ),
_oldNScanned( 0 ),
_honorRecordedPlan( honorRecordedPlan ),
_min( min.getOwned() ),
_max( max.getOwned() ),
_bestGuessOnly( bestGuessOnly ),
_mayYield( mayYield ),
_yieldSometimesTracker( 256, 20 ),
_mustAssertOnYieldFailure( mustAssertOnYieldFailure ) {
if ( hint && !hint->eoo() ) {
_hint = hint->wrap();
}
init();
}
bool QueryPlanSet::modifiedKeys() const {
for( PlanSet::const_iterator i = _plans.begin(); i != _plans.end(); ++i )
if ( (*i)->isMultiKey() )
return true;
return false;
}
bool QueryPlanSet::hasMultiKey() const {
for( PlanSet::const_iterator i = _plans.begin(); i != _plans.end(); ++i )
if ( (*i)->isMultiKey() )
return true;
return false;
}
void QueryPlanSet::addHint( IndexDetails &id ) {
if ( !_min.isEmpty() || !_max.isEmpty() ) {
string errmsg;
BSONObj keyPattern = id.keyPattern();
// This reformats _min and _max to be used for index lookup.
massert( 10365 , errmsg, indexDetailsForRange( _frsp->ns(), errmsg, _min, _max, keyPattern ) );
}
NamespaceDetails *d = nsdetails(_ns);
_plans.push_back( QueryPlanPtr( new QueryPlan( d, d->idxNo(id), *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure, _min, _max ) ) );
}
// returns an IndexDetails * for a hint, 0 if hint is $natural.
// hint must not be eoo()
IndexDetails *parseHint( const BSONElement &hint, NamespaceDetails *d ) {
massert( 13292, "hint eoo", !hint.eoo() );
if( hint.type() == String ) {
string hintstr = hint.valuestr();
NamespaceDetails::IndexIterator i = d->ii();
while( i.more() ) {
IndexDetails& ii = i.next();
if ( ii.indexName() == hintstr ) {
return ⅈ
}
}
}
else if( hint.type() == Object ) {
BSONObj hintobj = hint.embeddedObject();
uassert( 10112 , "bad hint", !hintobj.isEmpty() );
if ( !strcmp( hintobj.firstElementFieldName(), "$natural" ) ) {
return 0;
}
NamespaceDetails::IndexIterator i = d->ii();
while( i.more() ) {
IndexDetails& ii = i.next();
if( ii.keyPattern().woCompare(hintobj) == 0 ) {
return ⅈ
}
}
}
uassert( 10113 , "bad hint", false );
return 0;
}
void QueryPlanSet::init() {
DEBUGQO( "QueryPlanSet::init " << ns << "\t" << _originalQuery );
_runner.reset();
_plans.clear();
_mayRecordPlan = true;
_usingPrerecordedPlan = false;
const char *ns = _frsp->ns();
NamespaceDetails *d = nsdetails( ns );
if ( !d || !_frsp->matchPossible() ) {
// Table scan plan, when no matches are possible
_plans.push_back( QueryPlanPtr( new QueryPlan( d, -1, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) ) );
return;
}
BSONElement hint = _hint.firstElement();
if ( !hint.eoo() ) {
_mayRecordPlan = false;
IndexDetails *id = parseHint( hint, d );
if ( id ) {
addHint( *id );
}
else {
massert( 10366 , "natural order cannot be specified with $min/$max", _min.isEmpty() && _max.isEmpty() );
// Table scan plan
_plans.push_back( QueryPlanPtr( new QueryPlan( d, -1, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) ) );
}
return;
}
if ( !_min.isEmpty() || !_max.isEmpty() ) {
string errmsg;
BSONObj keyPattern;
IndexDetails *idx = indexDetailsForRange( ns, errmsg, _min, _max, keyPattern );
massert( 10367 , errmsg, idx );
_plans.push_back( QueryPlanPtr( new QueryPlan( d, d->idxNo(*idx), *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure, _min, _max ) ) );
return;
}
if ( isSimpleIdQuery( _originalQuery ) ) {
int idx = d->findIdIndex();
if ( idx >= 0 ) {
_usingPrerecordedPlan = true;
_mayRecordPlan = false;
_plans.push_back( QueryPlanPtr( new QueryPlan( d , idx , *_frsp , _originalFrsp.get() , _originalQuery, _order, _mustAssertOnYieldFailure ) ) );
return;
}
}
if ( _originalQuery.isEmpty() && _order.isEmpty() ) {
_plans.push_back( QueryPlanPtr( new QueryPlan( d, -1, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) ) );
return;
}
DEBUGQO( "\t special : " << _frsp->getSpecial() );
if ( _frsp->getSpecial().size() ) {
_special = _frsp->getSpecial();
NamespaceDetails::IndexIterator i = d->ii();
while( i.more() ) {
int j = i.pos();
IndexDetails& ii = i.next();
const IndexSpec& spec = ii.getSpec();
if ( spec.getTypeName() == _special && spec.suitability( _originalQuery , _order ) ) {
_usingPrerecordedPlan = true;
_mayRecordPlan = false;
_plans.push_back( QueryPlanPtr( new QueryPlan( d , j , *_frsp , _originalFrsp.get() , _originalQuery, _order ,
_mustAssertOnYieldFailure , BSONObj() , BSONObj() , _special ) ) );
return;
}
}
uassert( 13038 , (string)"can't find special index: " + _special + " for: " + _originalQuery.toString() , 0 );
}
if ( _honorRecordedPlan ) {
pair< BSONObj, long long > best = QueryUtilIndexed::bestIndexForPatterns( *_frsp, _order );
BSONObj bestIndex = best.first;
long long oldNScanned = best.second;
if ( !bestIndex.isEmpty() ) {
QueryPlanPtr p;
_oldNScanned = oldNScanned;
if ( !strcmp( bestIndex.firstElementFieldName(), "$natural" ) ) {
// Table scan plan
p.reset( new QueryPlan( d, -1, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) );
}
NamespaceDetails::IndexIterator i = d->ii();
while( i.more() ) {
int j = i.pos();
IndexDetails& ii = i.next();
if( ii.keyPattern().woCompare(bestIndex) == 0 ) {
p.reset( new QueryPlan( d, j, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) );
}
}
massert( 10368 , "Unable to locate previously recorded index", p.get() );
if ( !( _bestGuessOnly && p->scanAndOrderRequired() ) ) {
_usingPrerecordedPlan = true;
_mayRecordPlan = false;
_plans.push_back( p );
return;
}
}
}
addOtherPlans( false );
}
void QueryPlanSet::addOtherPlans( bool checkFirst ) {
const char *ns = _frsp->ns();
NamespaceDetails *d = nsdetails( ns );
if ( !d )
return;
// If table scan is optimal or natural order requested or tailable cursor requested
if ( !_frsp->matchPossible() || ( _frsp->noNontrivialRanges() && _order.isEmpty() ) ||
( !_order.isEmpty() && !strcmp( _order.firstElementFieldName(), "$natural" ) ) ) {
// Table scan plan
addPlan( QueryPlanPtr( new QueryPlan( d, -1, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) ), checkFirst );
return;
}
bool normalQuery = _hint.isEmpty() && _min.isEmpty() && _max.isEmpty();
PlanSet plans;
QueryPlanPtr optimalPlan;
for( int i = 0; i < d->nIndexes; ++i ) {
if ( normalQuery ) {
BSONObj keyPattern = d->idx( i ).keyPattern();
if ( !_frsp->matchPossibleForIndex( d, i, keyPattern ) ) {
// If no match is possible, only generate a trival plan that won't
// scan any documents.
QueryPlanPtr p( new QueryPlan( d, i, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) );
addPlan( p, checkFirst );
return;
}
if ( !QueryUtilIndexed::indexUseful( *_frsp, d, i, _order ) ) {
continue;
}
}
QueryPlanPtr p( new QueryPlan( d, i, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) );
if ( p->optimal() ) {
if ( !optimalPlan.get() ) {
optimalPlan = p;
}
}
else if ( !p->unhelpful() ) {
plans.push_back( p );
}
}
if ( optimalPlan.get() ) {
addPlan( optimalPlan, checkFirst );
return;
}
for( PlanSet::iterator i = plans.begin(); i != plans.end(); ++i )
addPlan( *i, checkFirst );
// Table scan plan
addPlan( QueryPlanPtr( new QueryPlan( d, -1, *_frsp, _originalFrsp.get(), _originalQuery, _order, _mustAssertOnYieldFailure ) ), checkFirst );
}
shared_ptr<QueryOp> QueryPlanSet::runOp( QueryOp &op ) {
if ( _usingPrerecordedPlan ) {
Runner r( *this, op );
shared_ptr<QueryOp> res = r.runUntilFirstCompletes();
// _plans.size() > 1 if addOtherPlans was called in Runner::runUntilFirstCompletes().
if ( _bestGuessOnly || res->complete() || _plans.size() > 1 )
return res;
// Retry with all candidate plans.
QueryUtilIndexed::clearIndexesForPatterns( *_frsp, _order );
init();
}
Runner r( *this, op );
return r.runUntilFirstCompletes();
}
shared_ptr<QueryOp> QueryPlanSet::nextOp( QueryOp &originalOp, bool retried ) {
if ( !_runner ) {
_runner.reset( new Runner( *this, originalOp ) );
shared_ptr<QueryOp> op = _runner->init();
if ( op->complete() ) {
return op;
}
}
shared_ptr<QueryOp> op = _runner->nextNonError();
if ( !op->error() ) {
return op;
}
if ( !_usingPrerecordedPlan || _bestGuessOnly || _plans.size() > 1 ) {
return op;
}
// Avoid an infinite loop here
uassert( 15878, str::stream() << "query plans not successful even with no constraints, potentially due to additional sort", ! retried );
// Retry with all candidate plans.
QueryUtilIndexed::clearIndexesForPatterns( *_frsp, _order );
init();
return nextOp( originalOp, true );
}
bool QueryPlanSet::prepareToYield() {
return _runner ? _runner->prepareToYield() : true;
}
void QueryPlanSet::recoverFromYield() {
if ( _runner ) {
_runner->recoverFromYield();
}
}
BSONObj QueryPlanSet::explain() const {
vector<BSONObj> arr;
for( PlanSet::const_iterator i = _plans.begin(); i != _plans.end(); ++i ) {
shared_ptr<Cursor> c = (*i)->newCursor();
BSONObjBuilder explain;
explain.append( "cursor", c->toString() );
explain.append( "indexBounds", c->prettyIndexBounds() );
arr.push_back( explain.obj() );
}
BSONObjBuilder b;
b.append( "allPlans", arr );
return b.obj();
}
QueryPlanSet::QueryPlanPtr QueryPlanSet::getBestGuess() const {
assert( _plans.size() );
if ( _plans[ 0 ]->scanAndOrderRequired() ) {
for ( unsigned i=1; i<_plans.size(); i++ ) {
if ( ! _plans[i]->scanAndOrderRequired() )
return _plans[i];
}
warning() << "best guess query plan requested, but scan and order are required for all plans "
<< " query: " << _originalQuery
<< " order: " << _order
<< " choices: ";
for ( unsigned i=0; i<_plans.size(); i++ )
warning() << _plans[i]->indexKey() << " ";
warning() << endl;
return QueryPlanPtr();
}
return _plans[0];
}
QueryPlanSet::Runner::Runner( QueryPlanSet &plans, QueryOp &op ) :
_op( op ),
_plans( plans ) {
}
bool QueryPlanSet::Runner::prepareToYield() {
for( vector<shared_ptr<QueryOp> >::const_iterator i = _ops.begin(); i != _ops.end(); ++i ) {
if ( !prepareToYieldOp( **i ) ) {
return false;
}
}
return true;
}
void QueryPlanSet::Runner::recoverFromYield() {
for( vector<shared_ptr<QueryOp> >::const_iterator i = _ops.begin(); i != _ops.end(); ++i ) {
recoverFromYieldOp( **i );
}
}
void QueryPlanSet::Runner::mayYield() {
if ( ! _plans._mayYield )
return;
if ( ! _plans._yieldSometimesTracker.ping() )
return;
int micros = ClientCursor::yieldSuggest();
if ( micros <= 0 )
return;
if ( !prepareToYield() )
return;
ClientCursor::staticYield( micros , _plans._ns , 0 );
recoverFromYield();
}
shared_ptr<QueryOp> QueryPlanSet::Runner::init() {
massert( 10369 , "no plans", _plans._plans.size() > 0 );
if ( _plans._bestGuessOnly ) {
shared_ptr<QueryOp> op( _op.createChild() );
op->setQueryPlan( _plans.getBestGuess().get() );
_ops.push_back( op );
}
else {
if ( _plans._plans.size() > 1 )
log(1) << " running multiple plans" << endl;
for( PlanSet::iterator i = _plans._plans.begin(); i != _plans._plans.end(); ++i ) {
shared_ptr<QueryOp> op( _op.createChild() );
op->setQueryPlan( i->get() );
_ops.push_back( op );
}
}
// Initialize ops.
for( vector<shared_ptr<QueryOp> >::iterator i = _ops.begin(); i != _ops.end(); ++i ) {
initOp( **i );
if ( (*i)->complete() )
return *i;
}
// Put runnable ops in the priority queue.
for( vector<shared_ptr<QueryOp> >::iterator i = _ops.begin(); i != _ops.end(); ++i ) {
if ( !(*i)->error() ) {
_queue.push( *i );
}
}
return *_ops.begin();
}
shared_ptr<QueryOp> QueryPlanSet::Runner::nextNonError() {
if ( _queue.empty() ) {
return *_ops.begin();
}
shared_ptr<QueryOp> ret;
do {
ret = next();
} while( ret->error() && !_queue.empty() );
return ret;
}
shared_ptr<QueryOp> QueryPlanSet::Runner::next() {
mayYield();
dassert( !_queue.empty() );
OpHolder holder = _queue.pop();
QueryOp &op = *holder._op;
nextOp( op );
if ( op.complete() ) {
if ( _plans._mayRecordPlan && op.mayRecordPlan() ) {
op.qp().registerSelf( op.nscanned() );
}
return holder._op;
}
if ( op.error() ) {
return holder._op;
}
_queue.push( holder );
if ( !_plans._bestGuessOnly && _plans._usingPrerecordedPlan && op.nscanned() > _plans._oldNScanned * 10 && _plans._special.empty() ) {
holder._offset = -op.nscanned();
_plans.addOtherPlans( /* avoid duplicating the initial plan */ true );
PlanSet::iterator i = _plans._plans.begin();
++i;
for( ; i != _plans._plans.end(); ++i ) {
shared_ptr<QueryOp> op( _op.createChild() );
op->setQueryPlan( i->get() );
_ops.push_back( op );
initOp( *op );
if ( op->complete() )
return op;
_queue.push( op );
}
_plans._mayRecordPlan = true;
_plans._usingPrerecordedPlan = false;
}
return holder._op;
}
shared_ptr<QueryOp> QueryPlanSet::Runner::runUntilFirstCompletes() {
shared_ptr<QueryOp> potentialFinisher = init();
if ( potentialFinisher->complete() ) {
return potentialFinisher;
}
while( !_queue.empty() ) {
shared_ptr<QueryOp> potentialFinisher = next();
if ( potentialFinisher->complete() ) {
return potentialFinisher;
}
}
return _ops[ 0 ];
}
#define GUARD_OP_EXCEPTION( op, expression ) \
try { \
expression; \
} \
catch ( DBException& e ) { \
op.setException( e.getInfo() ); \
} \
catch ( const std::exception &e ) { \
op.setException( ExceptionInfo( e.what() , 0 ) ); \
} \
catch ( ... ) { \
op.setException( ExceptionInfo( "Caught unknown exception" , 0 ) ); \
}
void QueryPlanSet::Runner::initOp( QueryOp &op ) {
GUARD_OP_EXCEPTION( op, op.init() );
}
void QueryPlanSet::Runner::nextOp( QueryOp &op ) {
GUARD_OP_EXCEPTION( op, if ( !op.error() ) { op.next(); } );
}
bool QueryPlanSet::Runner::prepareToYieldOp( QueryOp &op ) {
GUARD_OP_EXCEPTION( op,
if ( op.error() ) {
return true;
}
else {
return op.prepareToYield();
} );
return true;
}
void QueryPlanSet::Runner::recoverFromYieldOp( QueryOp &op ) {
GUARD_OP_EXCEPTION( op, if ( !op.error() ) { op.recoverFromYield(); } );
}
/**
* NOTE on our $or implementation: In our current qo implementation we don't
* keep statistics on our data, but we can conceptualize the problem of
* selecting an index when statistics exist for all index ranges. The
* d-hitting set problem on k sets and n elements can be reduced to the
* problem of index selection on k $or clauses and n index ranges (where
* d is the max number of indexes, and the number of ranges n is unbounded).
* In light of the fact that d-hitting set is np complete, and we don't even
* track statistics (so cost calculations are expensive) our first
* implementation uses the following greedy approach: We take one $or clause
* at a time and treat each as a separate query for index selection purposes.
* But if an index range is scanned for a particular $or clause, we eliminate
* that range from all subsequent clauses. One could imagine an opposite
* implementation where we select indexes based on the union of index ranges
* for all $or clauses, but this can have much poorer worst case behavior.
* (An index range that suits one $or clause may not suit another, and this
* is worse than the typical case of index range choice staleness because
* with $or the clauses may likely be logically distinct.) The greedy
* implementation won't do any worse than all the $or clauses individually,
* and it can often do better. In the first cut we are intentionally using
* QueryPattern tracking to record successful plans on $or clauses for use by
* subsequent $or clauses, even though there may be a significant aggregate
* $nor component that would not be represented in QueryPattern.
*/
MultiPlanScanner::MultiPlanScanner( const char *ns,
const BSONObj &query,
const BSONObj &order,
const BSONElement *hint,
bool honorRecordedPlan,
const BSONObj &min,
const BSONObj &max,
bool bestGuessOnly,
bool mayYield ) :
_ns( ns ),
_or( !query.getField( "$or" ).eoo() ),
_query( query.getOwned() ),
_i(),
_honorRecordedPlan( honorRecordedPlan ),
_bestGuessOnly( bestGuessOnly ),
_hint( ( hint && !hint->eoo() ) ? hint->wrap() : BSONObj() ),
_mayYield( mayYield ),
_tableScanned() {
if ( !order.isEmpty() || !min.isEmpty() || !max.isEmpty() ) {
_or = false;
}
if ( _or ) {
// Only construct an OrRangeGenerator if we may handle $or clauses.
_org.reset( new OrRangeGenerator( ns, _query ) );
if ( !_org->getSpecial().empty() ) {
_or = false;
}
else if ( uselessOr( _hint.firstElement() ) ) {
_or = false;
}
}
// if _or == false, don't use or clauses for index selection
if ( !_or ) {
auto_ptr<FieldRangeSetPair> frsp( new FieldRangeSetPair( ns, _query, true ) );
_currentQps.reset( new QueryPlanSet( ns, frsp, auto_ptr<FieldRangeSetPair>(), _query, order, false, hint, honorRecordedPlan, min, max, _bestGuessOnly, _mayYield ) );
}
else {
BSONElement e = _query.getField( "$or" );
massert( 13268, "invalid $or spec", e.type() == Array && e.embeddedObject().nFields() > 0 );
}
}
shared_ptr<QueryOp> MultiPlanScanner::runOpOnce( QueryOp &op ) {
assertMayRunMore();
if ( !_or ) {
++_i;
return _currentQps->runOp( op );
}
++_i;
auto_ptr<FieldRangeSetPair> frsp( _org->topFrsp() );
auto_ptr<FieldRangeSetPair> originalFrsp( _org->topFrspOriginal() );
BSONElement hintElt = _hint.firstElement();
_currentQps.reset( new QueryPlanSet( _ns, frsp, originalFrsp, _query, BSONObj(), true, &hintElt, _honorRecordedPlan, BSONObj(), BSONObj(), _bestGuessOnly, _mayYield ) );
shared_ptr<QueryOp> ret( _currentQps->runOp( op ) );
if ( ! ret->complete() )
throw MsgAssertionException( ret->exception() );
if ( ret->qp().willScanTable() ) {
_tableScanned = true;
} else {
// If the full table was scanned, don't bother popping the last or clause.
_org->popOrClause( ret->qp().nsd(), ret->qp().idxNo(), ret->qp().indexed() ? ret->qp().indexKey() : BSONObj() );
}
return ret;
}
shared_ptr<QueryOp> MultiPlanScanner::runOp( QueryOp &op ) {
shared_ptr<QueryOp> ret = runOpOnce( op );
while( !ret->stopRequested() && mayRunMore() ) {
ret = runOpOnce( *ret );
}
return ret;
}
shared_ptr<QueryOp> MultiPlanScanner::nextOpHandleEndOfClause() {
shared_ptr<QueryOp> op = _currentQps->nextOp( *_baseOp );
if ( !op->complete() ) {
return op;
}
if ( op->qp().willScanTable() ) {
_tableScanned = true;
} else {
_org->popOrClause( op->qp().nsd(), op->qp().idxNo(), op->qp().indexed() ? op->qp().indexKey() : BSONObj() );
}
return op;
}
shared_ptr<QueryOp> MultiPlanScanner::nextOpBeginningClause() {
assertMayRunMore();
shared_ptr<QueryOp> op;
while( mayRunMore() ) {
++_i;
auto_ptr<FieldRangeSetPair> frsp( _org->topFrsp() );
auto_ptr<FieldRangeSetPair> originalFrsp( _org->topFrspOriginal() );
BSONElement hintElt = _hint.firstElement();
_currentQps.reset( new QueryPlanSet( _ns, frsp, originalFrsp, _query, BSONObj(), true, &hintElt, _honorRecordedPlan, BSONObj(), BSONObj(), _bestGuessOnly, _mayYield ) );
op = nextOpHandleEndOfClause();
if ( !op->complete() ) {
return op;
}
_baseOp = op;
}
return op;
}
shared_ptr<QueryOp> MultiPlanScanner::nextOp() {
if ( !_or ) {
if ( _i == 0 ) {
assertMayRunMore();
++_i;
}
return _currentQps->nextOp( *_baseOp );
}
if ( _i == 0 ) {
return nextOpBeginningClause();
}
shared_ptr<QueryOp> op = nextOpHandleEndOfClause();
if ( !op->complete() ) {
return op;
}
if ( !op->stopRequested() && mayRunMore() ) {
// Finished scanning the clause, but stop hasn't been requested.
// Start scanning the next clause.
_baseOp = op;
return nextOpBeginningClause();
}
return op;
}
bool MultiPlanScanner::prepareToYield() {
return _currentQps.get() ? _currentQps->prepareToYield() : true;
}
void MultiPlanScanner::recoverFromYield() {
if ( _currentQps.get() ) {
_currentQps->recoverFromYield();
}
}
shared_ptr<Cursor> MultiPlanScanner::singleCursor() const {
if ( _or || _currentQps->nPlans() != 1 || _currentQps->firstPlan()->scanAndOrderRequired() ) {
return shared_ptr<Cursor>();
}
// If there is only one plan and it does not require an in memory
// sort, we do not expect its cursor op to throw an exception and
// so do not need a QueryOptimizerCursor to handle this case.
return _currentQps->firstPlan()->newCursor();
}
bool MultiPlanScanner::uselessOr( const BSONElement &hint ) const {
NamespaceDetails *nsd = nsdetails( _ns );
if ( !nsd ) {
return true;
}
if ( !hint.eoo() ) {
IndexDetails *id = parseHint( hint, nsd );
if ( !id ) {
return true;
}
return QueryUtilIndexed::uselessOr( *_org, nsd, nsd->idxNo( *id ) );
}
return QueryUtilIndexed::uselessOr( *_org, nsd, -1 );
}
MultiCursor::MultiCursor( const char *ns, const BSONObj &pattern, const BSONObj &order, shared_ptr<CursorOp> op, bool mayYield )
: _mps( new MultiPlanScanner( ns, pattern, order, 0, true, BSONObj(), BSONObj(), !op.get(), mayYield ) ), _nscanned() {
if ( op.get() ) {