pg_clickhouse v0.10: Subquery pushdown makes TPC-H queries 1000x faster
pg_clickhouse v0.10: Subquery pushdown and 1000x faster TPC-H queries
pg_clickhouse v0.10.0 pushes down correlated subqueries, enabling full pushdown for 16 of 22 TPC-H queries. A TPC-H Q17 query that took 32.7 seconds now runs in 37 ms. The release also introduces a new C client library, expands pushdown coverage for functions and aggregates, and fixes concurrency bugs in the binary driver.
Q17 is the trophy: a correlated subquery averaging l_quantity per part that, back when it evaluated once per outer row against 6M line items at scale factor 1, took 32.7 seconds. Fully pushed down, it's 37 milliseconds.