Current approach for execution is essentially a kind plan tree interpretation. JIT-compilation of queries means compilation of plan tree into binary. Such compilation could get rid of multiple levels of indirection therefore accelerating queries.
JIT-compilation of queries requires significant rework of infrastructure:
- JIT-ready representation for built-in and user functions.
- JIT-ready representation for some executor nodes and core functions.
- JIT support for access methods: allow compilation of supporting functions into index scan.