2️⃣ Expression Evaluation Improvements

[joocer]

The portion of the time spent on Expression Evaluation quickly grows as expressions become more complex.

The current set of proposed solutions, which is primarily based on using a faster execution language are:

• use LLVM
• use Gandiva
• use rust

Cython is expected to perform very similar performance to the existing code which is mainly Numpy / pyarrow, so has been considered but won't be progressed unless new information is presented to change this view.

Gandiva is the least favourable of the options due to the inability to acquire the library without significant effort.

Using rust also requires significant effort before it can be used, but is expected to be able to be used for other optimisations (we already use sqlparser-rs and orjson which are built on rust)

LLVM is expected to give the best performance, but is unlikely to be able to be used in other ways for improvements.