Make DataViewRowId not act like a number.

src/Microsoft.Data.DataView/DataViewRowId.cs

@@ -9,7 +9,7 @@
 namespace Microsoft.Data.DataView
 {
     /// <summary>
-    /// A structure serving as a sixteen-byte unsigned integer. It is used as the row id of <see cref="IDataView"/>.
+    /// A structure serving as the identifier of a row of <see cref="IDataView"/>.
     /// For datasets with millions of records, those IDs need to be unique, therefore the need for such a large structure to hold the values.
     /// Those Ids are derived from other Ids of the previous components of the pipelines, and dividing the structure in two: high order and low order of bits,
     /// and reduces the changes of those collisions even further.
@@ -53,70 +53,13 @@ public bool Equals(DataViewRowId other)
 
         public override bool Equals(object obj)
         {
-            if (obj != null && obj is DataViewRowId)
+            if (obj is DataViewRowId other)
             {
-                var item = (DataViewRowId)obj;
-                return Equals(item);
+                return Equals(other);
             }
             return false;
         }
 
-        public static DataViewRowId operator +(DataViewRowId first, ulong second)
-        {
-            ulong resHi = first.High;
-            ulong resLo = first.Low + second;
-            if (resLo < second)
-                resHi++;
-            return new DataViewRowId(resLo, resHi);
-        }
-
-        public static DataViewRowId operator -(DataViewRowId first, ulong second)
-        {
-            ulong resHi = first.High;
-            ulong resLo = first.Low - second;
-            if (resLo > first.Low)
-                resHi--;
-            return new DataViewRowId(resLo, resHi);
-        }
-
-        public static bool operator ==(DataViewRowId first, ulong second)
-        {
-            return first.High == 0 && first.Low == second;
-        }
-
-        public static bool operator !=(DataViewRowId first, ulong second)
-        {
-            return !(first == second);
-        }
-
-        public static bool operator <(DataViewRowId first, ulong second)
-        {
-            return first.High == 0 && first.Low < second;
-        }
-
-        public static bool operator >(DataViewRowId first, ulong second)
-        {
-            return first.High > 0 || first.Low > second;
-        }
-
-        public static bool operator <=(DataViewRowId first, ulong second)
-        {
-            return first.High == 0 && first.Low <= second;
-        }
-
-        public static bool operator >=(DataViewRowId first, ulong second)
-        {
-            return first.High > 0 || first.Low >= second;
-        }
-
-        public static explicit operator double(DataViewRowId x)
-        {
-            // REVIEW: The 64-bit JIT has a bug where rounding might be not quite
-            // correct when converting a ulong to double with the high bit set. Should we
-            // care and compensate? See the DoubleParser code for a work-around.
-            return x.High * ((double)(1UL << 32) * (1UL << 32)) + x.Low;
-        }
-
         public override int GetHashCode()
         {
             return (int)(

src/Microsoft.Data.DataView/DataViewType.cs

@@ -199,17 +199,6 @@ public static NumberDataViewType UInt64
             }
         }
 
-        private static volatile NumberDataViewType _instDataViewRowId;
-        public static NumberDataViewType DataViewRowId
-        {
-            get
-            {
-                return _instDataViewRowId ??
-                    Interlocked.CompareExchange(ref _instDataViewRowId, new NumberDataViewType(typeof(DataViewRowId), "UG"), null) ??
-                    _instDataViewRowId;
-            }
-        }
-
         private static volatile NumberDataViewType _instSingle;
         public static NumberDataViewType Single
         {
@@ -243,6 +232,41 @@ public override bool Equals(DataViewType other)
         public override string ToString() => _name;
     }
 
+    /// <summary>
+    /// The DataViewRowId type.
+    /// </summary>
+    public sealed class RowIdDataViewType : PrimitiveDataViewType
+    {
+        private static volatile RowIdDataViewType _instance;
+        public static RowIdDataViewType Instance
+        {
+            get
+            {
+                return _instance ??
+                    Interlocked.CompareExchange(ref _instance, new RowIdDataViewType(), null) ??
+                    _instance;
+            }
+        }
+
+        private RowIdDataViewType()
+            : base(typeof(DataViewRowId))
+        {
+        }
+
+        public override bool Equals(DataViewType other)
+        {
+            if (other == this)
+                return true;
+            Debug.Assert(!(other is RowIdDataViewType));
+            return false;
+        }
+
+        public override string ToString()
+        {
+            return "DataViewRowId";
+        }
+    }
+
     /// <summary>
     /// The standard boolean type.
     /// </summary>

src/Microsoft.ML.Core/Data/ColumnTypeExtensions.cs

@@ -19,7 +19,8 @@ internal static class ColumnTypeExtensions
         /// </summary>
         public static bool IsStandardScalar(this DataViewType columnType) =>
             (columnType is NumberDataViewType) || (columnType is TextDataViewType) || (columnType is BooleanDataViewType) ||
-            (columnType is TimeSpanDataViewType) || (columnType is DateTimeDataViewType) || (columnType is DateTimeOffsetDataViewType);
+            (columnType is RowIdDataViewType) || (columnType is TimeSpanDataViewType) ||
+            (columnType is DateTimeDataViewType) || (columnType is DateTimeOffsetDataViewType);
 
         /// <summary>
         /// Zero return means it's not a key type.
@@ -103,6 +104,8 @@ public static PrimitiveDataViewType PrimitiveTypeFromType(Type type)
                 return DateTimeDataViewType.Instance;
             if (type == typeof(DateTimeOffset))
                 return DateTimeOffsetDataViewType.Instance;
+            if (type == typeof(DataViewRowId))
+                return RowIdDataViewType.Instance;
             return NumberTypeFromType(type);
         }
 
@@ -118,6 +121,8 @@ public static PrimitiveDataViewType PrimitiveTypeFromKind(InternalDataKind kind)
                 return DateTimeDataViewType.Instance;
             if (kind == InternalDataKind.DZ)
                 return DateTimeOffsetDataViewType.Instance;
+            if (kind == InternalDataKind.UG)
+                return RowIdDataViewType.Instance;
             return NumberTypeFromKind(kind);
         }
 
@@ -131,7 +136,7 @@ public static NumberDataViewType NumberTypeFromType(Type type)
             throw new InvalidOperationException($"Bad type in {nameof(ColumnTypeExtensions)}.{nameof(NumberTypeFromType)}: {type}");
         }
 
-        public static NumberDataViewType NumberTypeFromKind(InternalDataKind kind)
+        private static NumberDataViewType NumberTypeFromKind(InternalDataKind kind)
         {
             switch (kind)
             {
@@ -155,8 +160,6 @@ public static NumberDataViewType NumberTypeFromKind(InternalDataKind kind)
                     return NumberDataViewType.Single;
                 case InternalDataKind.R8:
                     return NumberDataViewType.Double;
-                case InternalDataKind.UG:
-                    return NumberDataViewType.DataViewRowId;
             }
 
             Contracts.Assert(false);

src/Microsoft.ML.Data/Data/DataViewUtils.cs

@@ -357,7 +357,7 @@ private static DataViewRowCursor ConsolidateCore(IChannelProvider provider, Data
                     outPipes[i] = OutPipe.Create(type, pool);
                 }
                 int idIdx = activeToCol.Length + (int)ExtraIndex.Id;
-                outPipes[idIdx] = OutPipe.Create(NumberDataViewType.DataViewRowId, GetPool(NumberDataViewType.DataViewRowId, ourPools, idIdx));
+                outPipes[idIdx] = OutPipe.Create(RowIdDataViewType.Instance, GetPool(RowIdDataViewType.Instance, ourPools, idIdx));
 
                 // Create the structures to synchronize between the workers and the consumer.
                 const int toConsumeBound = 4;
@@ -553,7 +553,7 @@ private DataViewRowCursor[] SplitCore(IChannelProvider ch, DataViewRowCursor inp
                 int idIdx = activeToCol.Length + (int)ExtraIndex.Id;
                 inPipes[idIdx] = CreateIdInPipe(input);
                 for (int i = 0; i < cthd; ++i)
-                    outPipes[i][idIdx] = inPipes[idIdx].CreateOutPipe(NumberDataViewType.DataViewRowId);
+                    outPipes[i][idIdx] = inPipes[idIdx].CreateOutPipe(RowIdDataViewType.Instance);
 
                 var toConsume = new BlockingCollection<Batch>(toConsumeBound);
                 var batchColumnPool = new MadeObjectPool<BatchColumn[]>(() => new BatchColumn[inPipes.Length]);

src/Microsoft.ML.Data/DataLoadSave/Binary/Codecs.cs

@@ -159,7 +159,9 @@ private sealed class UnsafeTypeCodec<T> : SimpleCodec<T> where T : struct
             // Throws an exception if T is neither a TimeSpan nor a NumberType.
             private static DataViewType UnsafeColumnType(Type type)
             {
-                return type == typeof(TimeSpan) ? (DataViewType)TimeSpanDataViewType.Instance : ColumnTypeExtensions.NumberTypeFromType(type);
+                return type == typeof(TimeSpan) ?  TimeSpanDataViewType.Instance :
+                    type == typeof(DataViewRowId) ? (DataViewType)RowIdDataViewType.Instance :
+                    ColumnTypeExtensions.NumberTypeFromType(type);
             }
 
             public UnsafeTypeCodec(CodecFactory factory)

src/Microsoft.ML.Data/Transforms/Hashing.cs

@@ -1213,10 +1213,11 @@ internal void Save(ModelSaveContext ctx)
         internal static bool IsColumnTypeValid(DataViewType type)
         {
             var itemType = type.GetItemType();
-            return itemType is TextDataViewType || itemType is KeyType || itemType is NumberDataViewType || itemType is BooleanDataViewType;
+            return itemType is TextDataViewType || itemType is KeyType || itemType is NumberDataViewType ||
+                itemType is BooleanDataViewType || itemType is RowIdDataViewType;
         }
 
-        internal const string ExpectedColumnType = "Expected Text, Key, numeric or Boolean item type";
+        internal const string ExpectedColumnType = "Expected Text, Key, numeric, Boolean or DataViewRowId item type";
 
         /// <summary>
         /// Initializes a new instance of <see cref="HashingEstimator"/>.

src/Microsoft.ML.Data/Transforms/RowShufflingTransformer.cs

@@ -529,7 +529,7 @@ public Cursor(IChannelProvider provider, int poolRows, DataViewRowCursor input,
                         input.Schema[c].Type, RowCursorUtils.GetGetterAsDelegate(input, c));
                     _getters[ia] = CreateGetterDelegate(c);
                 }
-                var idPipe = _pipes[numActive + (int)ExtraIndex.Id] = ShufflePipe.Create(_pipeIndices.Length, NumberDataViewType.DataViewRowId, input.GetIdGetter());
+                var idPipe = _pipes[numActive + (int)ExtraIndex.Id] = ShufflePipe.Create(_pipeIndices.Length, RowIdDataViewType.Instance, input.GetIdGetter());
                 _idGetter = CreateGetterDelegate<DataViewRowId>(idPipe);
                 // Initially, after the preamble to MoveNextCore, we want:
                 // liveCount=0, deadCount=0, circularIndex=0. So we set these

src/Microsoft.ML.Parquet/ParquetLoader.cs

@@ -350,7 +350,7 @@ private DataViewType ConvertFieldType(DataType parquetType)
                 case DataType.Int64:
                     return NumberDataViewType.Int64;
                 case DataType.Int96:
-                    return NumberDataViewType.DataViewRowId;
+                    return RowIdDataViewType.Instance;
                 case DataType.ByteArray:
                     return new VectorType(NumberDataViewType.Byte);
                 case DataType.String:

src/Microsoft.ML.StaticPipe/StaticSchemaShape.cs

@@ -166,7 +166,7 @@ private static Type GetTypeOrNull(SchemaShape.Column col)
                 if (physType != null && (
                     pt == NumberDataViewType.SByte || pt == NumberDataViewType.Int16 || pt == NumberDataViewType.Int32 || pt == NumberDataViewType.Int32 ||
                     pt == NumberDataViewType.Byte || pt == NumberDataViewType.UInt16 || pt == NumberDataViewType.UInt32 || pt == NumberDataViewType.UInt32 ||
-                    pt == NumberDataViewType.Single || pt == NumberDataViewType.Double || pt == NumberDataViewType.DataViewRowId || pt == BooleanDataViewType.Instance ||
+                    pt == NumberDataViewType.Single || pt == NumberDataViewType.Double || pt == RowIdDataViewType.Instance || pt == BooleanDataViewType.Instance ||
                     pt == DateTimeDataViewType.Instance || pt == DateTimeOffsetDataViewType.Instance || pt == TimeSpanDataViewType.Instance ||
                     pt == TextDataViewType.Instance))
                 {
@@ -311,7 +311,7 @@ private static Type GetTypeOrNull(DataViewSchema.Column col)
                 if (physType != null && (
                     pt == NumberDataViewType.SByte || pt == NumberDataViewType.Int16 || pt == NumberDataViewType.Int32 || pt == NumberDataViewType.Int64 ||
                     pt == NumberDataViewType.Byte || pt == NumberDataViewType.UInt16 || pt == NumberDataViewType.UInt32 || pt == NumberDataViewType.UInt64 ||
-                    pt == NumberDataViewType.Single || pt == NumberDataViewType.Double || pt == NumberDataViewType.DataViewRowId || pt == BooleanDataViewType.Instance ||
+                    pt == NumberDataViewType.Single || pt == NumberDataViewType.Double || pt == RowIdDataViewType.Instance || pt == BooleanDataViewType.Instance ||
                     pt == DateTimeDataViewType.Instance || pt == DateTimeOffsetDataViewType.Instance || pt == TimeSpanDataViewType.Instance ||
                     pt == TextDataViewType.Instance))
                 {