SERVER-54490 Fix incorrect sort order for NaN and missing values in SBE

2 files changed, 10 insertions, 4 deletions

diff --git a/src/mongo/db/exec/sbe/values/value.cpp b/src/mongo/db/exec/sbe/values/value.cpp
index 3f8e9c7834d..f2dc9c1723a 100644
--- a/src/mongo/db/exec/sbe/values/value.cpp
+++ b/src/mongo/db/exec/sbe/values/value.cpp
@@ -31,6 +31,7 @@
 
 #include "mongo/db/exec/sbe/values/value.h"
 
+#include "mongo/base/compare_numbers.h"
 #include "mongo/db/exec/js_function.h"
 #include "mongo/db/exec/sbe/values/bson.h"
 #include "mongo/db/exec/sbe/values/value_builder.h"
@@ -690,13 +691,13 @@ std::pair<TypeTags, Value> compareValue(TypeTags lhsTag,
                 return {TypeTags::NumberInt32, bitcastFrom<int32_t>(result)};
             }
             case TypeTags::NumberDouble: {
-                auto result = compareHelper(numericCast<double>(lhsTag, lhsValue),
-                                            numericCast<double>(rhsTag, rhsValue));
+                auto result = compareDoubles(numericCast<double>(lhsTag, lhsValue),
+                                             numericCast<double>(rhsTag, rhsValue));
                 return {TypeTags::NumberInt32, bitcastFrom<int32_t>(result)};
             }
             case TypeTags::NumberDecimal: {
-                auto result = compareHelper(numericCast<Decimal128>(lhsTag, lhsValue),
-                                            numericCast<Decimal128>(rhsTag, rhsValue));
+                auto result = compareDecimals(numericCast<Decimal128>(lhsTag, lhsValue),
+                                              numericCast<Decimal128>(rhsTag, rhsValue));
                 return {TypeTags::NumberInt32, bitcastFrom<int32_t>(result)};
             }
             default:
diff --git a/src/mongo/db/query/sbe_stage_builder.cpp b/src/mongo/db/query/sbe_stage_builder.cpp
index 3a0d9821add..14c9870fb94 100644
--- a/src/mongo/db/query/sbe_stage_builder.cpp
+++ b/src/mongo/db/query/sbe_stage_builder.cpp
@@ -501,6 +501,11 @@ std::pair<std::unique_ptr<sbe::PlanStage>, PlanStageSlots> SlotBasedStageBuilder
                                             sbe::makeE<sbe::EVariable>(*collatorSlot));
         }
 
+        // According to MQL semantics, missing values are treated as nulls during sorting.
+        getSortFieldExpr = makeFunction("fillEmpty"sv,
+                                        std::move(getSortFieldExpr),
+                                        makeConstant(sbe::value::TypeTags::Null, 0));
+
         projectMap.emplace(sortFieldVar, std::move(getSortFieldExpr));
     }