tustvold opened a new issue, #1697: URL: https://github.com/apache/arrow-rs/issues/1697
**Which part is this question about** A MapArray is represented in parquet as follows, see [here](https://github.com/apache/parquet-format/blob/master/LogicalTypes.md#maps). ``` <map-repetition> group <name> (MAP) { repeated group key_value { required <key-type> key; <value-repetition> <value-type> value; } } ``` However, it is represented in arrow as ``` Field::new( <name>, DataType::Map( Box::new(Field::new("entries", DataType::Struct(..), <nullable>)) <is_sorted> ) <nullable> ) ``` The confusion lies in the fact we now have nullability at three levels: * Within the MapArray * Within the StructArray * Within the key and value arrays When the original parquet data only has nullability at two levels. The writer logic appears to ignore the nullability of the inner StructArray, which doesn't feel right. **Describe your question** * Should the inner StructArray always be not nullable? * Could we store `DataType` instead of `Field` in `DataType::Map` * Could we store the child `DataType` directly in `DataType::Map` **Additional context** https://github.com/apache/arrow-rs/issues/1642 also relates to the semantics of MapArrays Map Arrays were added by @nevi-me as part of https://github.com/apache/arrow-rs/issues/395 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
