diff options
Diffstat (limited to 'src/mongo/db/query/query_planner.cpp')
| -rw-r--r-- | src/mongo/db/query/query_planner.cpp | 66 |
1 files changed, 54 insertions, 12 deletions
diff --git a/src/mongo/db/query/query_planner.cpp b/src/mongo/db/query/query_planner.cpp index 600f106f25f..37d89750d2a 100644 --- a/src/mongo/db/query/query_planner.cpp +++ b/src/mongo/db/query/query_planner.cpp @@ -129,6 +129,40 @@ Status tagOrChildAccordingToCache(PlanCacheIndexTree* compositeCacheData, return Status::OK(); } + +/** + * Returns whether the hintedIndex matches the cluster key. When hinting by index name, + * 'hintObj' takes the shape of {$hint: <indexName>}. When hinting by key pattern, + * 'hintObj' represents the actual key pattern (eg: {_id: 1}). + */ +bool hintMatchesClusterKey(const boost::optional<ClusteredCollectionInfo>& clusteredInfo, + const BSONObj& hintObj) { + if (!clusteredInfo) { + // The collection isn't clustered. + return false; + } + + auto clusteredIndexSpec = clusteredInfo->getIndexSpec(); + + BSONElement firstHintElt = hintObj.firstElement(); + if (firstHintElt.fieldNameStringData() == "$hint"_sd && + firstHintElt.type() == BSONType::String) { + // An index name is provided by the hint. + + // The clusteredIndex's name should always be filled in with a default value when not + // specified upon creation. + tassert(6012100, + "clusteredIndex's 'name' field should be filled in by default after creation", + clusteredIndexSpec.getName()); + + auto hintName = firstHintElt.valueStringData(); + return hintName == clusteredIndexSpec.getName().get(); + } + + // An index spec is provided by the hint. + return hintObj.woCompare(clusteredIndexSpec.getKey()) == 0; +} + } // namespace using std::numeric_limits; @@ -671,21 +705,29 @@ StatusWith<std::vector<std::unique_ptr<QuerySolution>>> QueryPlanner::planForMul return {std::move(out)}; } - // The hint can be {$natural: +/-1}. If this happens, output a collscan. We expect any $natural - // sort to have been normalized to a $natural hint upstream. if (!query.getFindCommandRequest().getHint().isEmpty()) { const BSONObj& hintObj = query.getFindCommandRequest().getHint(); - if (hintObj[query_request_helper::kNaturalSortField]) { - LOGV2_DEBUG(20969, 5, "Forcing a table scan due to hinted $natural"); - if (!canTableScan) { - return Status(ErrorCodes::NoQueryExecutionPlans, - "hint $natural is not allowed, because 'notablescan' is enabled"); - } - if (!query.getFindCommandRequest().getMin().isEmpty() || - !query.getFindCommandRequest().getMax().isEmpty()) { - return Status(ErrorCodes::NoQueryExecutionPlans, - "min and max are incompatible with $natural"); + const auto naturalHint = hintObj[query_request_helper::kNaturalSortField]; + if (naturalHint || hintMatchesClusterKey(params.clusteredInfo, hintObj)) { + // The hint can be {$natural: +/-1}. If this happens, output a collscan. We expect any + // $natural sort to have been normalized to a $natural hint upstream. Additionally, if + // the hint matches the collection's cluster key, we also output a collscan utilizing + // the cluster key. + + if (naturalHint) { + // Perform validation specific to $natural. + LOGV2_DEBUG(20969, 5, "Forcing a table scan due to hinted $natural"); + if (!canTableScan) { + return Status(ErrorCodes::NoQueryExecutionPlans, + "hint $natural is not allowed, because 'notablescan' is enabled"); + } + if (!query.getFindCommandRequest().getMin().isEmpty() || + !query.getFindCommandRequest().getMax().isEmpty()) { + return Status(ErrorCodes::NoQueryExecutionPlans, + "min and max are incompatible with $natural"); + } } + auto soln = buildCollscanSoln(query, isTailable, params); if (!soln) { return Status(ErrorCodes::NoQueryExecutionPlans, |