Fix NaN handling for array_min and array_max (facebookincubator#9772)

Summary: Pull Request resolved: facebookincubator#9772 Ensure that: - Null is returned consistently for all types - NaN is treated as greater than infinity Differential Revision: D57237545
bikramSingh91 · May 13, 2024 · a37cd60 · a37cd60
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Showing 4 changed files with 83 additions and 95 deletions.
diff --git a/velox/docs/functions/presto/array.rst b/velox/docs/functions/presto/array.rst
@@ -94,30 +94,30 @@ Array Functions
 .. function:: array_max(array(E)) -> E
 
     Returns the maximum value of input array.
-    Returns NaN if E is REAL or DOUBLE and array contains a NaN value.
-    Returns NULL if array doesn't contain a NaN value, but contains a NULL value. ::
+    NaN is considered to be greater than Infinity.
+    Returns NULL if array contains a NULL value. ::
 
         SELECT array_max(ARRAY [1, 2, 3]); -- 3
         SELECT array_max(ARRAY [-1, -2, -2]); -- -1
         SELECT array_max(ARRAY [-1, -2, NULL]); -- NULL
         SELECT array_max(ARRAY []); -- NULL
-        SELECT array_max(ARRAY[NULL, nan()]); -- NaN
+        SELECT array_min(ARRAY [-1, nan(), NULL]); -- NULL
         SELECT array_max(ARRAY[{-1, -2, -3, nan()]); -- NaN
-        SELECT array_max(ARRAY[-0.0001, NULL, -0.0003, nan()]); -- NaN
+        SELECT array_max(ARRAY[{infinity(), nan()]); -- NaN
 
 .. function:: array_min(array(E)) -> E
 
     Returns the minimum value of input array.
-    Returns NaN if E is REAL or DOUBLE and array contains a NaN value.
-    Returns NULL if array doesn't contain a NaN value, but contains a NULL value. ::
+    NaN is considered to be greater than Infinity.
+    Returns NULL if array contains a NULL value. ::
 
         SELECT array_min(ARRAY [1, 2, 3]); -- 1
         SELECT array_min(ARRAY [-1, -2, -2]); -- -2
         SELECT array_min(ARRAY [-1, -2, NULL]); -- NULL
         SELECT array_min(ARRAY []); -- NULL
-        SELECT array_min(ARRAY[NULL, nan()]); -- NaN
-        SELECT array_min(ARRAY[{-1, -2, -3, nan()]); -- NaN
-        SELECT array_min(ARRAY[-0.0001, NULL, -0.0003, nan()]); -- NaN
+        SELECT array_min(ARRAY [-1, nan(), NULL]); -- NULL
+        SELECT array_min(ARRAY[{-1, -2, -3, nan()]); -- -1
+        SELECT array_max(ARRAY[{infinity(), nan()]); -- Infinity
 
 .. function:: array_normalize(array(E), E) -> array(E)
 

diff --git a/velox/functions/prestosql/ArrayFunctions.h b/velox/functions/prestosql/ArrayFunctions.h
@@ -21,6 +21,7 @@
 #include "velox/functions/Udf.h"
 #include "velox/functions/lib/CheckedArithmetic.h"
 #include "velox/type/Conversions.h"
+#include "velox/type/FloatingPointUtil.h"
 
 namespace facebook::velox::functions {
 
@@ -32,6 +33,18 @@ struct ArrayMinMaxFunction {
 
   template <typename T>
   void update(T& currentValue, const T& candidateValue) {
+    if constexpr (std::is_same_v<T, float> || std::is_same_v<T, double>) {
+      using namespace facebook::velox::util::floating_point;
+      if constexpr (isMax) {
+        if (NaNAwareGreaterThan<T>{}(candidateValue, currentValue)) {
+          currentValue = candidateValue;
+        }
+      } else {
+        if (NaNAwareLessThan<T>{}(candidateValue, currentValue)) {
+          currentValue = candidateValue;
+        }
+      }
+    }
     if constexpr (isMax) {
       if (candidateValue > currentValue) {
         currentValue = candidateValue;
@@ -52,71 +65,13 @@ struct ArrayMinMaxFunction {
     out.setNoCopy(value);
   }
 
-  template <typename TReturn, typename TInput>
-  bool callForFloatOrDouble(TReturn& out, const TInput& array) {
-    bool hasNull = false;
-    auto it = array.begin();
-
-    // Find the first non-null item (if any)
-    while (it != array.end()) {
-      if (it->has_value()) {
-        break;
-      }
-
-      hasNull = true;
-      ++it;
-    }
-
-    // Return false if end of array is reached without finding a non-null item.
-    if (it == array.end()) {
-      return false;
-    }
-
-    // If first non-null item is NAN, return immediately.
-    auto currentValue = it->value();
-    if (std::isnan(currentValue)) {
-      assign(out, currentValue);
-      return true;
-    }
-
-    ++it;
-    while (it != array.end()) {
-      if (it->has_value()) {
-        auto newValue = it->value();
-        if (std::isnan(newValue)) {
-          assign(out, newValue);
-          return true;
-        }
-        update(currentValue, newValue);
-      } else {
-        hasNull = true;
-      }
-      ++it;
-    }
-
-    // If we found a null, return false. Note that, if we found
-    // a NAN, the function will return at earlier stage as soon as
-    // a NAN is observed.
-    if (hasNull) {
-      return false;
-    }
-
-    assign(out, currentValue);
-    return true;
-  }
-
   template <typename TReturn, typename TInput>
   FOLLY_ALWAYS_INLINE bool call(TReturn& out, const TInput& array) {
     // Result is null if array is empty.
     if (array.size() == 0) {
       return false;
     }
 
-    if constexpr (
-        std::is_same_v<TReturn, float> || std::is_same_v<TReturn, double>) {
-      return callForFloatOrDouble(out, array);
-    }
-
     if (!array.mayHaveNulls()) {
       // Input array does not have nulls.
       auto currentValue = *array[0];

diff --git a/velox/functions/prestosql/tests/ArrayMaxTest.cpp b/velox/functions/prestosql/tests/ArrayMaxTest.cpp
@@ -145,24 +145,21 @@ TEST_F(ArrayMaxTest, longVarcharNoNulls) {
 
 // Test documented example.
 TEST_F(ArrayMaxTest, docs) {
-  auto input1 = makeNullableArrayVector<int32_t>(
-      {{1, 2, 3}, {-1, -2, -2}, {-1, -2, std::nullopt}, {}});
-  auto expected1 =
-      makeNullableFlatVector<int32_t>({3, -1, std::nullopt, std::nullopt});
-  testArrayMax(input1, expected1);
-
-  auto input2 = makeNullableArrayVector<double>(
-      {{std::nullopt, std::numeric_limits<double>::quiet_NaN()},
-       {-1, -2, -3, std::numeric_limits<double>::quiet_NaN()},
-       {-0.0001,
-        std::nullopt,
-        -0.0003,
-        std::numeric_limits<double>::quiet_NaN()}});
-  auto expected2 = makeNullableFlatVector<double>(
-      {std::numeric_limits<double>::quiet_NaN(),
-       std::numeric_limits<double>::quiet_NaN(),
-       std::numeric_limits<double>::quiet_NaN()});
-  testArrayMax(input2, expected2);
+  {
+    auto input = makeNullableArrayVector<int32_t>(
+        {{1, 2, 3}, {-1, -2, -2}, {-1, -2, std::nullopt}, {}});
+    auto expected =
+        makeNullableFlatVector<int32_t>({3, -1, std::nullopt, std::nullopt});
+    testArrayMax(input, expected);
+  }
+  {
+    static const float kNaN = std::numeric_limits<float>::quiet_NaN();
+    static const float kInfinity = std::numeric_limits<float>::infinity();
+    auto input = makeNullableArrayVector<float>(
+        {{-1, kNaN, std::nullopt}, {-1, -2, -3, kNaN}, {kInfinity, kNaN}});
+    auto expected = makeNullableFlatVector<float>({std::nullopt, kNaN, kNaN});
+    testArrayMax(input, expected);
+  }
 }
 
 template <typename Type>
@@ -293,6 +290,22 @@ class ArrayMaxFloatingPointTest : public FunctionBaseTest {
          0.0001});
     testArrayMax(input, expected);
   }
+
+  void testExtremeValues() {
+    static const T kNaN = std::numeric_limits<T>::quiet_NaN();
+    static const T kInfinity = std::numeric_limits<T>::infinity();
+    static const T kNegativeInfinity = -1 * std::numeric_limits<T>::infinity();
+    auto input = makeNullableArrayVector<T>(
+        {{-1, std::nullopt, kNaN},
+         {-1, std::nullopt, 2},
+         {-1, 0, 2},
+         {kNegativeInfinity, kNegativeInfinity},
+         {-1, 2, kInfinity},
+         {kInfinity, kNaN}});
+    auto expected = makeNullableFlatVector<T>(
+        {std::nullopt, std::nullopt, 2, kNegativeInfinity, kInfinity, kNaN});
+    testArrayMax(input, expected);
+  }
 };
 
 } // namespace
@@ -318,3 +331,7 @@ TYPED_TEST(ArrayMaxFloatingPointTest, arrayMaxNullable) {
 TYPED_TEST(ArrayMaxFloatingPointTest, arrayMax) {
   this->testNoNulls();
 }
+
+TYPED_TEST(ArrayMaxFloatingPointTest, arrayMaxExtreme) {
+  this->testExtremeValues();
+}
diff --git a/velox/functions/prestosql/tests/ArrayMinTest.cpp b/velox/functions/prestosql/tests/ArrayMinTest.cpp
@@ -43,17 +43,12 @@ class ArrayMinTest : public FunctionBaseTest {
         makeNullableFlatVector<int64_t>({1, -2, std::nullopt, std::nullopt});
     testExpr<int64_t>(expected1, "array_min(C0)", {input1});
 
+    static const float kNaN = std::numeric_limits<float>::quiet_NaN();
+    static const float kInfinity = std::numeric_limits<float>::infinity();
     auto input2 = makeNullableArrayVector<float>(
-        {{std::nullopt, std::numeric_limits<double>::quiet_NaN()},
-         {-1, -2, -3, std::numeric_limits<float>::quiet_NaN()},
-         {-0.0001,
-          std::nullopt,
-          -0.0003,
-          std::numeric_limits<float>::quiet_NaN()}});
-    auto expected2 = makeNullableFlatVector<float>(
-        {std::numeric_limits<float>::quiet_NaN(),
-         std::numeric_limits<float>::quiet_NaN(),
-         std::numeric_limits<float>::quiet_NaN()});
+        {{-1, kNaN, std::nullopt}, {-1, -2, -3, kNaN}, {kInfinity, kNaN}});
+    auto expected2 =
+        makeNullableFlatVector<float>({std::nullopt, -3, kInfinity});
 
     testExpr<float>(expected2, "array_min(C0)", {input2});
   }
@@ -185,6 +180,27 @@ TEST_F(ArrayMinTest, boolArrays) {
   testBool();
 }
 
+TEST_F(ArrayMinTest, floatArrays) {
+  auto testFloatingPoint = [&]<typename T>() {
+    static const T kNaN = std::numeric_limits<T>::quiet_NaN();
+    static const T kInfinity = std::numeric_limits<T>::infinity();
+    static const T kNegativeInfinity = -1 * std::numeric_limits<T>::infinity();
+    auto input = makeNullableArrayVector<T>(
+        {{-1, std::nullopt, kNaN},
+         {-1, std::nullopt, 2},
+         {-1, 0, 2},
+         {-1, kNegativeInfinity, kNaN},
+         {kInfinity, kNaN},
+         {kNaN, kNaN}});
+    auto expected = makeNullableFlatVector<T>(
+        {std::nullopt, std::nullopt, -1, kNegativeInfinity, kInfinity, kNaN});
+
+    testExpr<T>(expected, "array_min(C0)", {input});
+  };
+  testFloatingPoint.template operator()<float>();
+  testFloatingPoint.template operator()<double>();
+}
+
 TEST_F(ArrayMinTest, complexTypeElements) {
   auto elements = makeRowVector({
       makeFlatVector<int32_t>({1, 2, 3, 3, 2, 1}),