After SwissTable implements find() method in ARROW-13532, Grouper can add Find() method to its interface. Note that the main problem is that Grouper uses mutable member variables for storing temporary data, whenever it is doing hash table lookups, even when the hash table is used as read-only. Grouper is also not thread-safe, while Find() method ideally should be thread-safe, working on immutable object.

Reporter: Michal Nowakiewicz / @michalursa

Related issues:

• [C++] Query engine umbrella issue (is a child of)
• [C++][Compute] Add ExecNode for semi and anti-semi join (relates to)

_{Note: This issue was originally created as ARROW-13706. Please see the migration documentation for further details.}