SERVER-63902 Fix $natural hint on time-series collections

5 files changed, 35 insertions, 19 deletions

diff --git a/src/mongo/db/ops/write_ops_exec.cpp b/src/mongo/db/ops/write_ops_exec.cpp
index b0b23e3e42b..d1afdc8dde9 100644
--- a/src/mongo/db/ops/write_ops_exec.cpp
+++ b/src/mongo/db/ops/write_ops_exec.cpp
@@ -809,10 +809,8 @@ static SingleWriteResult performSingleUpdateOp(OperationContext* opCtx,
                 "Cannot perform an upsert on a time-series collection",
                 !updateRequest->isUpsert());
 
-        // Only translate the hint (if there is one) if it is specified with an index specification
-        // document.
-        if (!updateRequest->getHint().isEmpty() &&
-            updateRequest->getHint().firstElement().fieldNameStringData() != "$hint"_sd) {
+        // Only translate the hint if it is specified with an index key.
+        if (timeseries::isHintIndexKey(updateRequest->getHint())) {
             updateRequest->setHint(
                 uassertStatusOK(timeseries::createBucketsIndexSpecFromTimeseriesIndexSpec(
                     *timeseriesOptions, updateRequest->getHint())));
@@ -1144,10 +1142,8 @@ static SingleWriteResult performSingleDeleteOp(OperationContext* opCtx,
                 "Time-series buckets collection is missing time-series options",
                 timeseriesOptions);
 
-        // Only translate the hint if it is specified by index spec.
-        if (!request.getHint().isEmpty() &&
-            (request.getHint().firstElement().fieldNameStringData() != "$hint"_sd ||
-             request.getHint().firstElement().type() != BSONType::String)) {
+        // Only translate the hint if it is specified by index key.
+        if (timeseries::isHintIndexKey(request.getHint())) {
             request.setHint(
                 uassertStatusOK(timeseries::createBucketsIndexSpecFromTimeseriesIndexSpec(
                     *timeseriesOptions, request.getHint())));
diff --git a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
index 1dff8c06341..9338f2c237d 100644
--- a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
+++ b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
@@ -71,6 +71,14 @@ std::pair<std::string, std::string> extractControlPrefixAndKey(const StringData&
 StatusWith<BSONObj> createBucketsSpecFromTimeseriesSpec(const TimeseriesOptions& timeseriesOptions,
                                                         const BSONObj& timeseriesIndexSpecBSON,
                                                         bool isShardKeySpec) {
+    tassert(6390200, "Empty object is not a valid index spec", !timeseriesIndexSpecBSON.isEmpty());
+    tassert(6390201,
+            str::stream() << "Invalid index spec (perhaps it's a valid hint, that was incorrectly "
+                          << "passed to createBucketsSpecFromTimeseriesSpec): "
+                          << timeseriesIndexSpecBSON,
+            timeseriesIndexSpecBSON.firstElement().fieldNameStringData() != "$hint"_sd &&
+                timeseriesIndexSpecBSON.firstElement().fieldNameStringData() != "$natural"_sd);
+
     auto timeField = timeseriesOptions.getTimeField();
     auto metaField = timeseriesOptions.getMetaField();
 
@@ -474,4 +482,16 @@ bool doesBucketsIndexIncludeMeasurement(OperationContext* opCtx,
     return false;
 }
 
+bool isHintIndexKey(const BSONObj& obj) {
+    if (obj.isEmpty())
+        return false;
+    StringData fieldName = obj.firstElement().fieldNameStringData();
+    if (fieldName == "$hint"_sd)
+        return false;
+    if (fieldName == "$natural"_sd)
+        return false;
+
+    return true;
+}
+
 }  // namespace mongo::timeseries
diff --git a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h
index ca9fc2e1a77..ad1bb795fd2 100644
--- a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h
+++ b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h
@@ -88,4 +88,13 @@ bool doesBucketsIndexIncludeMeasurement(OperationContext* opCtx,
                                         const TimeseriesOptions& timeseriesOptions,
                                         const BSONObj& bucketsIndex);
 
+/**
+ * Takes a 'hint' object, in the same format used by FindCommandRequest, and returns
+ * true if the hint is an index key.
+ *
+ * Besides an index key, a hint can be {$hint: <index name>} or {$natural: <direction>},
+ * or it can be {} which means no hint is given.
+ */
+bool isHintIndexKey(const BSONObj& obj);
+
 }  // namespace mongo::timeseries
diff --git a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions_test.cpp b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions_test.cpp
index 88a2fd76b7d..db6eadda021 100644
--- a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions_test.cpp
+++ b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions_test.cpp
@@ -128,14 +128,6 @@ TEST(TimeseriesIndexSchemaConversionTest, OriginalSpecFieldName) {
     }
 }
 
-// {} <=> {}
-TEST(TimeseriesIndexSchemaConversionTest, EmptyTimeseriesIndexSpecDoesNothing) {
-    TimeseriesOptions timeseriesOptions = makeTimeseriesOptions();
-    BSONObj emptyIndexSpec = {};
-
-    testBothWaysIndexSpecConversion(timeseriesOptions, emptyIndexSpec, emptyIndexSpec);
-}
-
 // {tm: 1} <=> {control.min.tm: 1, control.max.tm: 1}
 TEST(TimeseriesIndexSchemaConversionTest, AscendingTimeIndexSpecConversion) {
     TimeseriesOptions timeseriesOptions = makeTimeseriesOptions();
diff --git a/src/mongo/db/views/resolved_view.cpp b/src/mongo/db/views/resolved_view.cpp
index ec60c6f0826..244d38a0b55 100644
--- a/src/mongo/db/views/resolved_view.cpp
+++ b/src/mongo/db/views/resolved_view.cpp
@@ -183,9 +183,8 @@ AggregateCommandRequest ResolvedView::asExpandedViewAggregation(
     if (request.getHint() && _timeseriesOptions) {
         BSONObj original = *request.getHint();
         BSONObj rewritten = original;
-        // Only convert if we are given an index spec, not an index name. An index name is provided
-        // in the form of {"$hint": <name>}.
-        if (!original.isEmpty() && original.firstElementFieldNameStringData() != "$hint"_sd) {
+        // Only convert if we are given an index spec, not an index name or a $natural hint.
+        if (timeseries::isHintIndexKey(original)) {
             auto converted = timeseries::createBucketsIndexSpecFromTimeseriesIndexSpec(
                 *_timeseriesOptions, original);
             if (converted.isOK()) {