Polars Evaluates Expressions in an Arena
Polars lowers the user-facing Expr tree into a flat Arena of nodes addressed by integer Node handles, which the physical planner walks to build Arc operators.
Lazy
Polars Kills Duplicate Subplans by Fingerprinting Them
Polars does not compare subtrees with a recursive equality check. It hashes each plan node together with the canonical ids of its children, interns the result in a hash table of …
Polars Simplifies the Expression Tree Before It Runs Anything
Simplification is not a separate optimizer pass in Polars but a rewrite rule that runs interleaved with type coercion during conversion, using a context flag that tells the rule …