[GitHub] [arrow] wjones127 commented on a diff in pull request #34632: GH-34536: [Parquet][C++] Overwrite default config for DeltaBitPackEncoder

["wjones127 (via GitHub)" <gi...@apache.org>]

wjones127 commented on code in PR #34632:
URL: https://github.com/apache/arrow/pull/34632#discussion_r1153737392


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cpp/src/parquet/encoding.cc:
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@@ -2107,9 +2107,12 @@ class DictByteArrayDecoderImpl : public DictDecoderImpl<ByteArrayType>,
 
 template <typename DType>
 class DeltaBitPackEncoder : public EncoderImpl, virtual public TypedEncoder<DType> {
+  static_assert(std::is_same_v<int32_t, typename DType::c_type> ||
+                std::is_same_v<int64_t, typename DType::c_type>);
   // Maximum possible header size
   static constexpr uint32_t kMaxPageHeaderWriterSize = 32;
-  static constexpr uint32_t kValuesPerBlock = 128;
+  static constexpr uint32_t kValuesPerBlock =
+      std::is_same_v<int32_t, typename DType::c_type> ? 128 : 256;
   static constexpr uint32_t kMiniBlocksPerBlock = 4;

Review Comment:
   Just to make sure I understand, is this where the 128 / 256 are coming from here?
   ```suggestion
     static constexpr uint32_t kMiniBlocksPerBlock = 4;
     static constexpr uint32_t kValuesPerBlock = kMiniBlocksPerBlock * sizeof(typename DType::c_type);
   ```



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