Given a "map", an obvious operation is to get an item corresponding to a key. The idea here is to create a kernel that does this for each map in the array.

IIRC MapArray isn't guaranteed to have unique keys. So one version would return an array of ItemType by returning the first of last item for a given key. Yet another version could return a ListType containing all matching items. 

Reporter: Will Jones / @wjones127
Assignee: Dhruv Vats / @dhruv9vats

Related issues:

• [C++] Add basic support for nested field refs in scanning (is related to)

PRs and other links:

• GitHub Pull Request #12162

_{Note: This issue was originally created as ARROW-15089. Please see the migration documentation for further details.}