Drop Seek requirement for ParquetWriter

[vlushn]

The Seek trait bound on arrow::file::writer::ParquetWriter prevents streaming parquet directly over a messaging bus. In the implementation, it seems to be used mainly for writing metadata about the size of the data body and the footer: https://github.com/apache/arrow-rs/blob/master/parquet/src/file/writer.rs#L196

It looks like the trait bound can be removed if the information on the number of bytes written is kept track of.

[jorgecarleitao]

Fwiw I was able to achieve this in parquet2, but required re-writing the thirft library to offer us that number of written bytes. This is not doable without a backward incompatible change in thirft library.

[vlushn]

Fwiw I was able to achieve this in parquet2, but required re-writing the thirft library to offer us that number of written bytes. This is not doable without a backward incompatible change in thirft library.

Oh, good to know. Do you think it might be possible to wrap the writer to collect the cumulative count of written bytes - it could be enough...

[jorgecarleitao]

That is an excelent idea. Kudos for that!

[tustvold]

Closed by #1719