add decimal column reader support

velox/dwio/dwrf/common/FileMetadata.cpp

@@ -92,7 +92,13 @@ TypeKind TypeWrapper::kind() const {
       return TypeKind::VARCHAR;
     case proto::orc::Type_Kind_DATE:
       return TypeKind::DATE;
-    case proto::orc::Type_Kind_DECIMAL:
+    case proto::orc::Type_Kind_DECIMAL: {
+      if (orcPtr()->precision() <= 18) {
+        return TypeKind::SHORT_DECIMAL;
+      } else {
+        return TypeKind::LONG_DECIMAL;
+      }
+    }
     case proto::orc::Type_Kind_CHAR:
     case proto::orc::Type_Kind_TIMESTAMP_INSTANT:
       DWIO_RAISE(

velox/dwio/dwrf/reader/CMakeLists.txt

@@ -27,6 +27,8 @@ add_library(
   SelectiveStringDirectColumnReader.cpp
   SelectiveStringDictionaryColumnReader.cpp
   SelectiveTimestampColumnReader.cpp
+  SelectiveShortDecimalColumnReader.cpp
+  SelectiveLongDecimalColumnReader.cpp
   SelectiveStructColumnReader.cpp
   SelectiveRepeatedColumnReader.cpp
   StripeDictionaryCache.cpp

velox/dwio/dwrf/reader/DwrfReader.cpp

@@ -436,6 +436,12 @@ std::optional<size_t> DwrfRowReader::estimatedRowSizeHelper(
       }
       return totalEstimate;
     }
+    case TypeKind::SHORT_DECIMAL: {
+      return valueCount * sizeof(uint64_t);
+    }
+    case TypeKind::LONG_DECIMAL: {
+      return valueCount * sizeof(uint128_t);
+    }
     default:
       return std::nullopt;
   }

velox/dwio/dwrf/reader/ReaderBase.cpp

@@ -314,6 +314,12 @@ std::shared_ptr<const Type> ReaderBase::convertType(
       // child doesn't hold.
       return ROW(std::move(names), std::move(tl));
     }
+    case TypeKind::LONG_DECIMAL:
+      return LONG_DECIMAL(
+          type.getOrcPtr()->precision(), type.getOrcPtr()->scale());
+    case TypeKind::SHORT_DECIMAL:
+      return SHORT_DECIMAL(
+          type.getOrcPtr()->precision(), type.getOrcPtr()->scale());
     default:
       DWIO_RAISE("Unknown type kind");
   }

velox/dwio/dwrf/reader/SelectiveDwrfReader.cpp

@@ -22,7 +22,9 @@
 #include "velox/dwio/dwrf/reader/SelectiveFloatingPointColumnReader.h"
 #include "velox/dwio/dwrf/reader/SelectiveIntegerDictionaryColumnReader.h"
 #include "velox/dwio/dwrf/reader/SelectiveIntegerDirectColumnReader.h"
+#include "velox/dwio/dwrf/reader/SelectiveLongDecimalColumnReader.h"
 #include "velox/dwio/dwrf/reader/SelectiveRepeatedColumnReader.h"
+#include "velox/dwio/dwrf/reader/SelectiveShortDecimalColumnReader.h"
 #include "velox/dwio/dwrf/reader/SelectiveStringDictionaryColumnReader.h"
 #include "velox/dwio/dwrf/reader/SelectiveStringDirectColumnReader.h"
 #include "velox/dwio/dwrf/reader/SelectiveStructColumnReader.h"
@@ -126,6 +128,12 @@ std::unique_ptr<SelectiveColumnReader> SelectiveDwrfReader::build(
     case TypeKind::TIMESTAMP:
       return std::make_unique<SelectiveTimestampColumnReader>(
           requestedType, params, scanSpec);
+    case TypeKind::SHORT_DECIMAL:
+      return std::make_unique<SelectiveShortDecimalColumnReader>(
+          requestedType, dataType->type, params, scanSpec);
+    case TypeKind::LONG_DECIMAL:
+      return std::make_unique<SelectiveLongDecimalColumnReader>(
+          requestedType, dataType->type, params, scanSpec);
     default:
       DWIO_RAISE(
           "buildReader unhandled type: " +

velox/dwio/dwrf/reader/SelectiveLongDecimalColumnReader.cpp

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "velox/dwio/dwrf/reader/SelectiveLongDecimalColumnReader.h"
+#include "velox/dwio/common/BufferUtil.h"
+#include "velox/dwio/dwrf/common/DecoderUtil.h"
+#include "velox/dwio/dwrf/reader/SelectiveShortDecimalColumnReader.h"
+
+namespace facebook::velox::dwrf {
+
+using namespace dwio::common;
+
+void SelectiveLongDecimalColumnReader::read(
+    vector_size_t offset,
+    RowSet rows,
+    const uint64_t* incomingNulls) {
+  // because scale's type is int64_t
+  prepareRead<int64_t>(offset, rows, incomingNulls);
+
+  bool isDense = rows.back() == rows.size() - 1;
+  velox::common::Filter* filter =
+      scanSpec_->filter() ? scanSpec_->filter() : &alwaysTrue();
+
+  if (scanSpec_->keepValues()) {
+    if (scanSpec_->valueHook()) {
+      if (isDense) {
+        processValueHook<true>(rows, scanSpec_->valueHook());
+      } else {
+        processValueHook<false>(rows, scanSpec_->valueHook());
+      }
+      return;
+    }
+
+    if (isDense) {
+      processFilter<true>(filter, ExtractToReader(this), rows);
+    } else {
+      processFilter<false>(filter, ExtractToReader(this), rows);
+    }
+  } else {
+    if (isDense) {
+      processFilter<true>(filter, DropValues(), rows);
+    } else {
+      processFilter<false>(filter, DropValues(), rows);
+    }
+  }
+}
+
+namespace {
+void scaleInt128(int128_t& value, uint32_t scale, uint32_t currentScale) {
+  if (scale > currentScale) {
+    while (scale > currentScale) {
+      uint32_t scaleAdjust = std::min(
+          SelectiveShortDecimalColumnReader::MAX_PRECISION_64,
+          scale - currentScale);
+      value *= SelectiveShortDecimalColumnReader::POWERS_OF_TEN[scaleAdjust];
+      currentScale += scaleAdjust;
+    }
+  } else if (scale < currentScale) {
+    int128_t remainder;
+    while (currentScale > scale) {
+      uint32_t scaleAdjust = std::min(
+          SelectiveShortDecimalColumnReader::MAX_PRECISION_64,
+          currentScale - scale);
+      // TODO: YYM
+      // value =
+      // value.divide(SelectiveShortDecimalColumnReader::POWERS_OF_TEN[scaleAdjust],
+      // remainder);
+      currentScale -= scaleAdjust;
+    }
+  }
+}
+} // namespace
+
+void SelectiveLongDecimalColumnReader::getValues(
+    RowSet rows,
+    VectorPtr* result) {
+  auto nullsPtr = nullsInReadRange_
+      ? (returnReaderNulls_ ? nullsInReadRange_->as<uint64_t>()
+                            : rawResultNulls_)
+      : nullptr;
+
+  auto decimalValues =
+      AlignedBuffer::allocate<UnscaledLongDecimal>(numValues_, &memoryPool_);
+  auto rawDecimalValues = decimalValues->asMutable<UnscaledLongDecimal>();
+
+  auto scales = scaleBuffer_->as<int64_t>();
+  auto values = values_->as<int128_t>();
+
+  // transfer to UnscaledLongDecimal
+  for (vector_size_t i = 0; i < numValues_; i++) {
+    if (!nullsPtr || !bits::isBitNull(nullsPtr, i)) {
+      int32_t currentScale = scales[i];
+      int128_t value = values[i];
+
+      scaleInt128(value, scale_, currentScale);
+
+      rawDecimalValues[i] = UnscaledLongDecimal(value);
+    }
+  }
+
+  values_ = decimalValues;
+  rawValues_ = values_->asMutable<char>();
+  getFlatValues<UnscaledLongDecimal, UnscaledLongDecimal>(
+      rows, result, type_, true);
+}
+
+} // namespace facebook::velox::dwrf