ClifHouck commented on code in PR #40957:
URL: https://github.com/apache/arrow/pull/40957#discussion_r1578248707
##########
cpp/src/parquet/encoding.cc:
##########
@@ -3988,4 +3988,56 @@ std::unique_ptr<Decoder> MakeDictDecoder(Type::type
type_num,
}
} // namespace detail
+ //
+ //
+bool IsParquetVersionAtLeast2_0(ParquetVersion::type parquet_version) {
+ switch (parquet_version) {
+ case ParquetVersion::PARQUET_1_0:
+ return false;
+ case ParquetVersion::PARQUET_2_4:
+ return true;
+ case ParquetVersion::PARQUET_2_6:
+ return true;
+ default:
+ return parquet_version > ParquetVersion::PARQUET_1_0;
+ }
+ return false;
+}
+
+// Informed heavily by
https://github.com/apache/parquet-format/blob/master/Encodings.md
+// and
+//
https://github.com/apache/arrow-rs/blob/a15adf66a8212fdb3a0222a32130ce70cfc28cf5/parquet/src/column/writer/mod.rs#L1183
+Encoding::type ChooseNonDictEncoding(Type::type data_type,
+ ParquetVersion::type parquet_version,
+ ParquetDataPageVersion datapage_version) {
+ switch (data_type) {
+ case Type::BOOLEAN:
+ if (IsParquetVersionAtLeast2_0(parquet_version) &&
+ datapage_version == ParquetDataPageVersion::V2) {
+ return Encoding::RLE;
+ }
+ break;
+
+ case Type::INT32:
+ case Type::INT64:
+ if (IsParquetVersionAtLeast2_0(parquet_version)) {
+ return Encoding::DELTA_BINARY_PACKED;
+ }
+ break;
+
+ case Type::INT96:
+ case Type::FLOAT:
+ case Type::DOUBLE:
+ return Encoding::PLAIN;
+
+ case Type::BYTE_ARRAY:
+ return Encoding::DELTA_LENGTH_BYTE_ARRAY;
Review Comment:
Probably, added.
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