Hi folks, I see that the member `tld_ <https://github.com/apache/arrow/blob/0ac0f733ff61f2db45cbff54def8768b3ceb8a9d/cpp/src/arrow/compute/exec/query_context.h#L150>` in class `QueryContext` is used by `BloomFilterPushdownContext <https://github.com/apache/arrow/blob/main/cpp/src/arrow/compute/exec/hash_join_node.cc>` and `SwissJoin <https://github.com/apache/arrow/blob/main/cpp/src/arrow/compute/exec/swiss_join.cc>`, both of which are parts of hash join node.
I'm wondering if there is any particular reason to design it this way. It seems reasonable to move it into hash join node - in which there exists per-thread states - and subsequently pass it down to the `BloomFilterPushdownContext` and `SwissJoin`. This way the `QueryContext` could stay thread-local-state-agnostic. Please help. Thanks in advance. *Rossi Sun*
