goldmedal opened a new issue, #11437:
URL: https://github.com/apache/datafusion/issues/11437
### Is your feature request related to a problem or challenge?
In most databases, the map type only allows unique keys. Refer to the
behavior of DuckDB:
```
D select map {'1':1, '1':2};
Invalid Input Error: Map keys must be unique.
```
However, the specification of
[MapArray](https://github.com/apache/arrow/blob/5e451d85d7269d3fb9c7eaab06caece5718c40e5/format/Schema.fbs#L117-L145)
states:
```
/// In this layout, the keys and values are each respectively contiguous. We
do
/// not constrain the key and value types, so the application is responsible
/// for ensuring that the keys are hashable and unique. Whether the keys are
sorted
/// may be set in the metadata for this field.
```
MapArray is not responsible for ensuring the uniqueness of keys. Therefore,
we should ensure the keys are unique on the application side (DataFusion).
### Describe the solution you'd like
We can check the keys are distinct when invoking the `map` and `make_map`
functions.
### Describe alternatives you've considered
_No response_
### Additional context
_No response_
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