Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Further optimize the hash join algorithm

Describe the solution you'd like
There are a couple of optimizations we could implement:

• Vectorize the row-equality check which now uses the equal_rows functions. We should be able to speed this up by vectorizing this, and also specialize it for handling non-null batches too. We probably can utilize the kernels take and eq here.
• Don't use a Hashmap but a Vec (or similar) with a certain amount of buckets (proportional to the number of rows or the expected number of keys in the left side). I tried this, but as it causes much more collisions than we have currently, it causes a big (3x) slowdown, so vectorizing the collision check is a prerequisite.

Additional context

https://www.cockroachlabs.com/blog/vectorized-hash-joiner/
https://dare.uva.nl/search?identifier=5ccbb60a-38b8-4eeb-858a-e7735dd37487