enable DateTime64 to be version column

src/DataTypes/DataTypeDateTime64.h

@@ -35,6 +35,8 @@ public:
 
     bool canBePromoted() const override { return false; }
 
+    bool canBeUsedAsVersion() const override { return true; }
+
 protected:
     SerializationPtr doGetDefaultSerialization() const override;
 };

src/DataTypes/IDataType.h

@@ -177,7 +177,7 @@ public:
       */
     virtual bool canBeComparedWithCollation() const { return false; }
 
-    /** If the type is totally comparable (Ints, Date, DateTime, not nullable, not floats)
+    /** If the type is totally comparable (Ints, Date, DateTime, DateTime64, not nullable, not floats)
       *  and "simple" enough (not String, FixedString) to be used as version number
       *  (to select rows with maximum version).
       */

src/Storages/MergeTree/MergeTreeData.cpp

@@ -630,7 +630,7 @@ void MergeTreeData::MergingParams::check(const StorageInMemoryMetadata & metadat
                     throw Exception("The column " + version_column +
                         " cannot be used as a version column for storage " + storage +
                         " because it is of type " + column.type->getName() +
-                        " (must be of an integer type or of type Date or DateTime)", ErrorCodes::BAD_TYPE_OF_FIELD);
+                        " (must be of an integer type or of type Date/DateTime/DateTime64)", ErrorCodes::BAD_TYPE_OF_FIELD);
                 miss_column = false;
                 break;
             }