[C++] field's metadata is not written to Parquet file

[asfimport]

I used this code to test the metadata write into file and read back behavior of parquet  file:

https://gist.github.com/dantrim/33f9f14d0b2d3ec45c022aa05f7a45ee

 

The generated file does not have metadata when I read the file in using code below and print it out: 
 

std::shared_ptrarrow::io::ReadableFile infile;
PARQUET_ASSIGN_OR_THROW(infile,
arrow::io::ReadableFile::Open("./test.parquet", arrow::default_memory_pool()));

std::unique_ptrparquet::arrow::FileReader reader;
PARQUET_THROW_NOT_OK(
parquet::arrow::OpenFile(infile, arrow::default_memory_pool(), &reader));
std::shared_ptrarrow::Table table;
PARQUET_THROW_NOT_OK(reader->ReadTable(&table));
EXPECT_EQ(frameCount, table->num_rows());
std::cout<<"==="<schema()->ToString(true) <<std::endl; /// no meta shown
Here is the version info:
libparquet-dev/focal,now 7.0.0-1 amd64 [installed]
libparquet-glib-dev/focal,now 7.0.0-1 amd64 [installed]
libparquet-glib700/focal,now 7.0.0-1 amd64 [installed,automatic]
libparquet700/focal,now 7.0.0-1 amd64 [installed,automatic]

Environment: Ubuntu
Reporter: Sifang Li

Related issues:

• [C++][Parquet] Field-level metadata are not supported? (ColumnMetadata.key_value_metadata) (is duplicated by)
• [C++][Parquet] Field-level metadata are not supported? (ColumnMetadata.key_value_metadata) (is related to)

_{Note: This issue was originally created as ARROW-15790. Please see the migration documentation for further details.}

[asfimport]

Sifang Li:
I can see in writer.cc - the metadata is apparently ignored:

 
Status Init() {
returnSchemaManifest::Make(writer_->schema(), /schema_metadata=/nullptr,
default_arrow_reader_properties(), &schema_manifest_);
}

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
Currently, if you want to preserve Arrow's field metadata in a Parquet roundtrip, you need to set the parquet::ArrowWriterProperties::store_schema option to true. This will store a serialized arrow schema in the Parquet FileMetaData, and restore information from this when reading.

For actually supporting reading/writing field / column-level metadata in Parquet, see ARROW-15548

[asfimport]

Sifang Li:
yes - that worked for me - it would be nice if they are stored automatically because I cannot imagine it would take up much space or why people would want that info dropped in any scenarios.

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
Well, see ARROW-15548 for some discussion on why this is not yet supported (for a start, we don't yet expose ColumnMetaData.key_value_metadata).

I am going to close this as a duplicate of ARROW-15548, we can continue the discussion there.