What's new in pg_clickhouse v0.10.0: Subqueries, TPC-H Speedups, C Driver, and Aggregates

Summary

pg_clickhouse v0.10.0 expands pushdown for analytic workloads, with full pushdown across the TPC-H suite remaining the stated target. The release moves the scoreboard from 12 of 22 fully pushed-down queries to 16, including Q17, which falls from 32.7 seconds to 37 milliseconds when its correlated aggregate subquery is shipped to ClickHouse. SubPlan handling now turns PostgreSQL subqueries into ClickHouse subqueries, while NOT IN and related operators receive guards that preserve PostgreSQL’s three-valued NULL semantics; compatibility requires ClickHouse 25.8 or later for the correlated-subquery shape. The binary driver was rebuilt on a plain-C client library and hardened against concurrency bugs. The release also broadens pushed-down functions and aggregates, adds clickhouse_perform() and clickhouse_server_version(), and leaves six TPC-H queries plus other roadmap items unresolved.

Takeaways

1. 1

   TPC-H coverage increased from 12 of 22 fully pushed-down queries to 16; Q17 improved from 32.7 seconds to 37 milliseconds after its correlated aggregate subquery was pushed down.

2. 2

   NOT IN and related operators use consumption-aware NULL guards to match PostgreSQL semantics, while non-nullable cases can use simpler native ClickHouse expressions.

3. 3

   clickhouse_perform() handles statements without row results, and clickhouse_raw_query() is deprecated in favor of configured-server functions with managed connection and driver selection.