The motivations are:
1. The API uses a SINGLE predicate and adds that to many chunks. With
`Arc<Vec<...>>` you gain nothing, with `Vec<Arc<...>>` the predicate
is only stored once (in many vectors)
2. While we currently add predicates blindly to all chunks, we can be way
smarter in the future and prune out tables, partitions or even single
chunks (based on statistics). With that, it will be rare that many
chunks share the exact same set of predicates.
3. It would be nice if we could de-duplicate predicates when writing them
to the preserved catalog without needing to repeat the pruning
discussed in point 2. This is way easier to implement whan chunks
exists in `Arc`s.
4. As a side-note: the `Arc<Vec<...>>` wasn't really cloned around but
instead was created many time. So the new version should be more
memory efficient out of the box.
Two reasons:
1. I wanna decouple `parquet_file` from `query` (nearly done, needs a
small follow-up PR).
2. `predicate` will have more and more features (like serialization)
which justifies a new home
Marco Neumann
kodiakhq[bot]
Nga Tran