[ARROW-8231] [Rust] Parse key_value_metadata from parquet FileMetaData into arrow schema metadata

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.17.0
• Component/s: Rust
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/24428
• Assignee: Jörn Horstmann
• Reporter: Jörn Horstmann
• Created: 26/Mar/20 17:03
• Updated: 11/Jan/23 07:59
• Resolved: 27/Mar/20 20:36

Description

The parquet-format FileMetaData struct contains optional key value pairs with additional metadata about the schema:

https://docs.rs/parquet-format/2.6.0/src/parquet_format/parquet_format.rs.html#3821

When the parquet file was generated using the java avro parquet writer, this for example contains the original avro schema under the `parquet.avro.schema` or `avro.schema` keys.

It would be nice if this metadata was accessible through the `arrow::datatypes::Schema.metadata` field.

I'm willing to implement and create a pull request for this feature.

Issue Links

• links to: GitHub Pull Request #6742