> December's headline feature was teaching the planner to push a whole correlated EXISTS subquery down as a single LEFT SEMI JOIN instead of a nested loop with one ClickHouse round trip per outer row. This moved the needle from 3 of 22 TPC-H queries all the way to 12.
LLMs sure love throwing in archaic expressions such as "move the needle". The abrupt contrast in jargons is so unpleasant and keeps throwing me off right in the middle of reading.