summaryrefslogtreecommitdiff
path: root/src/mongo/db/query/canonical_query.cpp
blob: 701a5fd2545f48a3326ae9e3cd8df48c9a331bae (plain)
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
/**
 *    Copyright (C) 2013 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/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery

#include "mongo/platform/basic.h"

#include "mongo/db/query/canonical_query.h"

#include "mongo/db/jsobj.h"
#include "mongo/db/query/query_planner_common.h"
#include "mongo/util/log.h"

namespace mongo {
namespace {

/**
 * Comparator for MatchExpression nodes.  Returns an integer less than, equal to, or greater
 * than zero if 'lhs' is less than, equal to, or greater than 'rhs', respectively.
 *
 * Sorts by:
 * 1) operator type (MatchExpression::MatchType)
 * 2) path name (MatchExpression::path())
 * 3) sort order of children
 * 4) number of children (MatchExpression::numChildren())
 *
 * The third item is needed to ensure that match expression trees which should have the same
 * cache key always sort the same way. If you're wondering when the tuple (operator type, path
 * name) could ever be equal, consider this query:
 *
 * {$and:[{$or:[{a:1},{a:2}]},{$or:[{a:1},{b:2}]}]}
 *
 * The two OR nodes would compare as equal in this case were it not for tuple item #3 (sort
 * order of children).
 */
int matchExpressionComparator(const MatchExpression* lhs, const MatchExpression* rhs) {
    MatchExpression::MatchType lhsMatchType = lhs->matchType();
    MatchExpression::MatchType rhsMatchType = rhs->matchType();
    if (lhsMatchType != rhsMatchType) {
        return lhsMatchType < rhsMatchType ? -1 : 1;
    }

    StringData lhsPath = lhs->path();
    StringData rhsPath = rhs->path();
    int pathsCompare = lhsPath.compare(rhsPath);
    if (pathsCompare != 0) {
        return pathsCompare;
    }

    const size_t numChildren = std::min(lhs->numChildren(), rhs->numChildren());
    for (size_t childIdx = 0; childIdx < numChildren; ++childIdx) {
        int childCompare =
            matchExpressionComparator(lhs->getChild(childIdx), rhs->getChild(childIdx));
        if (childCompare != 0) {
            return childCompare;
        }
    }

    if (lhs->numChildren() != rhs->numChildren()) {
        return lhs->numChildren() < rhs->numChildren() ? -1 : 1;
    }

    // They're equal!
    return 0;
}

bool matchExpressionLessThan(const MatchExpression* lhs, const MatchExpression* rhs) {
    return matchExpressionComparator(lhs, rhs) < 0;
}

}  // namespace

//
// These all punt to the many-argumented canonicalize below.
//

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    const BSONObj emptyObj;
    return CanonicalQuery::canonicalize(ns, query, emptyObj, emptyObj, 0, 0, whereCallback);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    bool explain,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    const BSONObj emptyObj;
    return CanonicalQuery::canonicalize(ns,
                                        query,
                                        emptyObj,  // sort
                                        emptyObj,  // projection
                                        0,         // skip
                                        0,         // limit
                                        emptyObj,  // hint
                                        emptyObj,  // min
                                        emptyObj,  // max
                                        false,     // snapshot
                                        explain,
                                        whereCallback);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    long long skip,
    long long limit,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    const BSONObj emptyObj;
    return CanonicalQuery::canonicalize(ns, query, emptyObj, emptyObj, skip, limit, whereCallback);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    const BSONObj& sort,
    const BSONObj& proj,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    return CanonicalQuery::canonicalize(ns, query, sort, proj, 0, 0, whereCallback);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    const BSONObj& sort,
    const BSONObj& proj,
    long long skip,
    long long limit,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    const BSONObj emptyObj;
    return CanonicalQuery::canonicalize(
        ns, query, sort, proj, skip, limit, emptyObj, whereCallback);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    const BSONObj& sort,
    const BSONObj& proj,
    long long skip,
    long long limit,
    const BSONObj& hint,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    const BSONObj emptyObj;
    return CanonicalQuery::canonicalize(ns,
                                        query,
                                        sort,
                                        proj,
                                        skip,
                                        limit,
                                        hint,
                                        emptyObj,
                                        emptyObj,
                                        false,  // snapshot
                                        false,  // explain
                                        whereCallback);
}

//
// These actually call init() on the CQ.
//

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const QueryMessage& qm, const MatchExpressionParser::WhereCallback& whereCallback) {
    // Make LiteParsedQuery.
    auto lpqStatus = LiteParsedQuery::fromLegacyQueryMessage(qm);
    if (!lpqStatus.isOK()) {
        return lpqStatus.getStatus();
    }

    return CanonicalQuery::canonicalize(lpqStatus.getValue().release(), whereCallback);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    LiteParsedQuery* lpq, const MatchExpressionParser::WhereCallback& whereCallback) {
    std::unique_ptr<LiteParsedQuery> autoLpq(lpq);

    // Make MatchExpression.
    StatusWithMatchExpression swme =
        MatchExpressionParser::parse(autoLpq->getFilter(), whereCallback);
    if (!swme.isOK()) {
        return swme.getStatus();
    }

    // Make the CQ we'll hopefully return.
    std::unique_ptr<CanonicalQuery> cq(new CanonicalQuery());

    // Takes ownership of lpq and the MatchExpression* in swme.
    Status initStatus = cq->init(autoLpq.release(), whereCallback, swme.getValue());

    if (!initStatus.isOK()) {
        return initStatus;
    }
    return std::move(cq);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const CanonicalQuery& baseQuery,
    MatchExpression* root,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    // Pass empty sort and projection.
    BSONObj emptyObj;

    // 0, 0, 0 is 'ntoskip', 'ntoreturn', and 'queryoptions'
    // false, false is 'snapshot' and 'explain'
    auto lpqStatus = LiteParsedQuery::makeAsOpQuery(baseQuery.ns(),
                                                    0,
                                                    0,
                                                    0,
                                                    baseQuery.getParsed().getFilter(),
                                                    baseQuery.getParsed().getProj(),
                                                    baseQuery.getParsed().getSort(),
                                                    emptyObj,
                                                    emptyObj,
                                                    emptyObj,
                                                    false,
                                                    false);
    if (!lpqStatus.isOK()) {
        return lpqStatus.getStatus();
    }

    // Make the CQ we'll hopefully return.
    std::unique_ptr<CanonicalQuery> cq(new CanonicalQuery());
    Status initStatus =
        cq->init(lpqStatus.getValue().release(), whereCallback, root->shallowClone());

    if (!initStatus.isOK()) {
        return initStatus;
    }
    return std::move(cq);
}

// static
StatusWith<std::unique_ptr<CanonicalQuery>> CanonicalQuery::canonicalize(
    const std::string& ns,
    const BSONObj& query,
    const BSONObj& sort,
    const BSONObj& proj,
    long long skip,
    long long limit,
    const BSONObj& hint,
    const BSONObj& minObj,
    const BSONObj& maxObj,
    bool snapshot,
    bool explain,
    const MatchExpressionParser::WhereCallback& whereCallback) {
    // Pass empty sort and projection.
    BSONObj emptyObj;

    auto lpqStatus = LiteParsedQuery::makeAsOpQuery(
        ns, skip, limit, 0, query, proj, sort, hint, minObj, maxObj, snapshot, explain);
    if (!lpqStatus.isOK()) {
        return lpqStatus.getStatus();
    }

    auto& lpq = lpqStatus.getValue();

    // Build a parse tree from the BSONObj in the parsed query.
    StatusWithMatchExpression swme = MatchExpressionParser::parse(lpq->getFilter(), whereCallback);
    if (!swme.isOK()) {
        return swme.getStatus();
    }

    // Make the CQ we'll hopefully return.
    std::unique_ptr<CanonicalQuery> cq(new CanonicalQuery());
    // Takes ownership of lpq and the MatchExpression* in swme.
    Status initStatus = cq->init(lpq.release(), whereCallback, swme.getValue());

    if (!initStatus.isOK()) {
        return initStatus;
    }
    return std::move(cq);
}

Status CanonicalQuery::init(LiteParsedQuery* lpq,
                            const MatchExpressionParser::WhereCallback& whereCallback,
                            MatchExpression* root) {
    _pq.reset(lpq);

    // Normalize, sort and validate tree.
    root = normalizeTree(root);

    sortTree(root);
    _root.reset(root);
    Status validStatus = isValid(root, *_pq);
    if (!validStatus.isOK()) {
        return validStatus;
    }

    // Validate the projection if there is one.
    if (!_pq->getProj().isEmpty()) {
        ParsedProjection* pp;
        Status projStatus = ParsedProjection::make(_pq->getProj(), _root.get(), &pp, whereCallback);
        if (!projStatus.isOK()) {
            return projStatus;
        }
        _proj.reset(pp);
    }

    return Status::OK();
}


// static
bool CanonicalQuery::isSimpleIdQuery(const BSONObj& query) {
    bool hasID = false;

    BSONObjIterator it(query);
    while (it.more()) {
        BSONElement elt = it.next();
        if (str::equals("_id", elt.fieldName())) {
            // Verify that the query on _id is a simple equality.
            hasID = true;

            if (elt.type() == Object) {
                // If the value is an object, it can't have a query operator
                // (must be a literal object match).
                if (elt.Obj().firstElementFieldName()[0] == '$') {
                    return false;
                }
            } else if (!elt.isSimpleType() && BinData != elt.type()) {
                // The _id fild cannot be something like { _id : { $gt : ...
                // But it can be BinData.
                return false;
            }
        } else if (elt.fieldName()[0] == '$' && (str::equals("$isolated", elt.fieldName()) ||
                                                 str::equals("$atomic", elt.fieldName()))) {
            // ok, passthrough
        } else {
            // If the field is not _id, it must be $isolated/$atomic.
            return false;
        }
    }

    return hasID;
}

// static
MatchExpression* CanonicalQuery::normalizeTree(MatchExpression* root) {
    // root->isLogical() is true now.  We care about AND, OR, and NOT. NOR currently scares us.
    if (MatchExpression::AND == root->matchType() || MatchExpression::OR == root->matchType()) {
        // We could have AND of AND of AND.  Make sure we clean up our children before merging
        // them.
        // UNITTEST 11738048
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }

        // If any of our children are of the same logical operator that we are, we remove the
        // child's children and append them to ourselves after we examine all children.
        std::vector<MatchExpression*> absorbedChildren;

        for (size_t i = 0; i < root->numChildren();) {
            MatchExpression* child = root->getChild(i);
            if (child->matchType() == root->matchType()) {
                // AND of an AND or OR of an OR.  Absorb child's children into ourself.
                for (size_t j = 0; j < child->numChildren(); ++j) {
                    absorbedChildren.push_back(child->getChild(j));
                }
                // TODO(opt): this is possibly n^2-ish
                root->getChildVector()->erase(root->getChildVector()->begin() + i);
                child->getChildVector()->clear();
                // Note that this only works because we cleared the child's children
                delete child;
                // Don't increment 'i' as the current child 'i' used to be child 'i+1'
            } else {
                ++i;
            }
        }

        root->getChildVector()->insert(
            root->getChildVector()->end(), absorbedChildren.begin(), absorbedChildren.end());

        // AND of 1 thing is the thing, OR of 1 thing is the thing.
        if (1 == root->numChildren()) {
            MatchExpression* ret = root->getChild(0);
            root->getChildVector()->clear();
            delete root;
            return ret;
        }
    } else if (MatchExpression::NOT == root->matchType()) {
        // Normalize the rest of the tree hanging off this NOT node.
        NotMatchExpression* nme = static_cast<NotMatchExpression*>(root);
        MatchExpression* child = nme->releaseChild();
        // normalizeTree(...) takes ownership of 'child', and then
        // transfers ownership of its return value to 'nme'.
        nme->resetChild(normalizeTree(child));
    } else if (MatchExpression::ELEM_MATCH_VALUE == root->matchType()) {
        // Just normalize our children.
        for (size_t i = 0; i < root->getChildVector()->size(); ++i) {
            (*root->getChildVector())[i] = normalizeTree(root->getChild(i));
        }
    }

    return root;
}

// static
void CanonicalQuery::sortTree(MatchExpression* tree) {
    for (size_t i = 0; i < tree->numChildren(); ++i) {
        sortTree(tree->getChild(i));
    }
    std::vector<MatchExpression*>* children = tree->getChildVector();
    if (NULL != children) {
        std::sort(children->begin(), children->end(), matchExpressionLessThan);
    }
}

// static
size_t CanonicalQuery::countNodes(const MatchExpression* root, MatchExpression::MatchType type) {
    size_t sum = 0;
    if (type == root->matchType()) {
        sum = 1;
    }
    for (size_t i = 0; i < root->numChildren(); ++i) {
        sum += countNodes(root->getChild(i), type);
    }
    return sum;
}

/**
 * Does 'root' have a subtree of type 'subtreeType' with a node of type 'childType' inside?
 */
bool hasNodeInSubtree(MatchExpression* root,
                      MatchExpression::MatchType childType,
                      MatchExpression::MatchType subtreeType) {
    if (subtreeType == root->matchType()) {
        return QueryPlannerCommon::hasNode(root, childType);
    }
    for (size_t i = 0; i < root->numChildren(); ++i) {
        if (hasNodeInSubtree(root->getChild(i), childType, subtreeType)) {
            return true;
        }
    }
    return false;
}

// static
Status CanonicalQuery::isValid(MatchExpression* root, const LiteParsedQuery& parsed) {
    // Analysis below should be done after squashing the tree to make it clearer.

    // There can only be one TEXT.  If there is a TEXT, it cannot appear inside a NOR.
    //
    // Note that the query grammar (as enforced by the MatchExpression parser) forbids TEXT
    // inside of value-expression clauses like NOT, so we don't check those here.
    size_t numText = countNodes(root, MatchExpression::TEXT);
    if (numText > 1) {
        return Status(ErrorCodes::BadValue, "Too many text expressions");
    } else if (1 == numText) {
        if (hasNodeInSubtree(root, MatchExpression::TEXT, MatchExpression::NOR)) {
            return Status(ErrorCodes::BadValue, "text expression not allowed in nor");
        }
    }

    // There can only be one NEAR.  If there is a NEAR, it must be either the root or the root
    // must be an AND and its child must be a NEAR.
    size_t numGeoNear = countNodes(root, MatchExpression::GEO_NEAR);
    if (numGeoNear > 1) {
        return Status(ErrorCodes::BadValue, "Too many geoNear expressions");
    } else if (1 == numGeoNear) {
        bool topLevel = false;
        if (MatchExpression::GEO_NEAR == root->matchType()) {
            topLevel = true;
        } else if (MatchExpression::AND == root->matchType()) {
            for (size_t i = 0; i < root->numChildren(); ++i) {
                if (MatchExpression::GEO_NEAR == root->getChild(i)->matchType()) {
                    topLevel = true;
                    break;
                }
            }
        }
        if (!topLevel) {
            return Status(ErrorCodes::BadValue, "geoNear must be top-level expr");
        }
    }

    // NEAR cannot have a $natural sort or $natural hint.
    if (numGeoNear > 0) {
        BSONObj sortObj = parsed.getSort();
        if (!sortObj["$natural"].eoo()) {
            return Status(ErrorCodes::BadValue,
                          "geoNear expression not allowed with $natural sort order");
        }

        BSONObj hintObj = parsed.getHint();
        if (!hintObj["$natural"].eoo()) {
            return Status(ErrorCodes::BadValue,
                          "geoNear expression not allowed with $natural hint");
        }
    }

    // TEXT and NEAR cannot both be in the query.
    if (numText > 0 && numGeoNear > 0) {
        return Status(ErrorCodes::BadValue, "text and geoNear not allowed in same query");
    }

    // TEXT and {$natural: ...} sort order cannot both be in the query.
    if (numText > 0) {
        const BSONObj& sortObj = parsed.getSort();
        BSONObjIterator it(sortObj);
        while (it.more()) {
            BSONElement elt = it.next();
            if (str::equals("$natural", elt.fieldName())) {
                return Status(ErrorCodes::BadValue,
                              "text expression not allowed with $natural sort order");
            }
        }
    }

    // TEXT and hint cannot both be in the query.
    if (numText > 0 && !parsed.getHint().isEmpty()) {
        return Status(ErrorCodes::BadValue, "text and hint not allowed in same query");
    }

    // TEXT and snapshot cannot both be in the query.
    if (numText > 0 && parsed.isSnapshot()) {
        return Status(ErrorCodes::BadValue, "text and snapshot not allowed in same query");
    }

    return Status::OK();
}

// static
// XXX TODO: This does not belong here at all.
MatchExpression* CanonicalQuery::logicalRewrite(MatchExpression* tree) {
    // Only thing we do is pull an OR up at the root.
    if (MatchExpression::AND != tree->matchType()) {
        return tree;
    }

    // We want to bail out ASAP if we have nothing to do here.
    size_t numOrs = 0;
    for (size_t i = 0; i < tree->numChildren(); ++i) {
        if (MatchExpression::OR == tree->getChild(i)->matchType()) {
            ++numOrs;
        }
    }

    // Only do this for one OR right now.
    if (1 != numOrs) {
        return tree;
    }

    // Detach the OR from the root.
    invariant(NULL != tree->getChildVector());
    std::vector<MatchExpression*>& rootChildren = *tree->getChildVector();
    MatchExpression* orChild = NULL;
    for (size_t i = 0; i < rootChildren.size(); ++i) {
        if (MatchExpression::OR == rootChildren[i]->matchType()) {
            orChild = rootChildren[i];
            rootChildren.erase(rootChildren.begin() + i);
            break;
        }
    }

    // AND the existing root with each or child.
    invariant(NULL != orChild);
    invariant(NULL != orChild->getChildVector());
    std::vector<MatchExpression*>& orChildren = *orChild->getChildVector();
    for (size_t i = 0; i < orChildren.size(); ++i) {
        AndMatchExpression* ama = new AndMatchExpression();
        ama->add(orChildren[i]);
        ama->add(tree->shallowClone());
        orChildren[i] = ama;
    }
    delete tree;

    // Clean up any consequences from this tomfoolery.
    return normalizeTree(orChild);
}

std::string CanonicalQuery::toString() const {
    str::stream ss;
    ss << "ns=" << _pq->ns();

    if (_pq->getBatchSize()) {
        ss << " batchSize=" << *_pq->getBatchSize();
    }

    if (_pq->getLimit()) {
        ss << " limit=" << *_pq->getLimit();
    }

    ss << " skip=" << _pq->getSkip() << "\n";

    // The expression tree puts an endl on for us.
    ss << "Tree: " << _root->toString();
    ss << "Sort: " << _pq->getSort().toString() << '\n';
    ss << "Proj: " << _pq->getProj().toString() << '\n';
    return ss;
}

std::string CanonicalQuery::toStringShort() const {
    str::stream ss;
    ss << "query: " << _pq->getFilter().toString() << " sort: " << _pq->getSort().toString()
       << " projection: " << _pq->getProj().toString() << " skip: " << _pq->getSkip();

    if (_pq->getBatchSize()) {
        ss << " batchSize: " << *_pq->getBatchSize();
    }

    if (_pq->getLimit()) {
        ss << " limit: " << *_pq->getLimit();
    }

    return ss;
}

}  // namespace mongo