[GitHub] [parquet-format] mapleFU commented on pull request #198: PARQUET-2264: Allow scale == precision for DecimalType

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

mapleFU commented on PR #198:
URL: https://github.com/apache/parquet-format/pull/198#issuecomment-1499297787

   ```
   diff --git a/cpp/examples/parquet/parquet_arrow/reader_writer.cc b/cpp/examples/parquet/parquet_arrow/reader_writer.cc
   index f5d96ec16..a4c4e5f77 100644
   --- a/cpp/examples/parquet/parquet_arrow/reader_writer.cc
   +++ b/cpp/examples/parquet/parquet_arrow/reader_writer.cc
   @@ -27,10 +27,12 @@
    // To have some input data, we first create an Arrow Table that holds
    // some data.
    std::shared_ptr<arrow::Table> generate_table() {
   -  arrow::Int64Builder i64builder;
   -  PARQUET_THROW_NOT_OK(i64builder.AppendValues({1, 2, 3, 4, 5}));
   -  std::shared_ptr<arrow::Array> i64array;
   -  PARQUET_THROW_NOT_OK(i64builder.Finish(&i64array));
   +  arrow::Decimal128Builder decimalBuilder(arrow::decimal(15, 15));
   +  for (int i = 0; i < 5; ++i) {
   +    PARQUET_THROW_NOT_OK(decimalBuilder.Append(arrow::Decimal128()));
   +  }
   +  std::shared_ptr<arrow::Array> decimalArray;
   +  PARQUET_THROW_NOT_OK(decimalBuilder.Finish(&decimalArray));
    
      arrow::StringBuilder strbuilder;
      PARQUET_THROW_NOT_OK(strbuilder.Append("some"));
   @@ -42,9 +44,9 @@ std::shared_ptr<arrow::Table> generate_table() {
      PARQUET_THROW_NOT_OK(strbuilder.Finish(&strarray));
    
      std::shared_ptr<arrow::Schema> schema = arrow::schema(
   -      {arrow::field("int", arrow::int64()), arrow::field("str", arrow::utf8())});
   +      {arrow::field("decimal", arrow::decimal(15, 15)), arrow::field("str", arrow::utf8())});
    
   -  return arrow::Table::Make(schema, {i64array, strarray});
   +  return arrow::Table::Make(schema, {decimalArray, strarray});
    }
    
    // #1 Write out the data as a Parquet file
   ```
   
   I've do an experiment with C++ arrow parquet, and it's able to write decimal with `Decimal(15, 15)`. So I think this patch is ok


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