What's New in pg_clickhouse v0.3.2: Postgres 19, TLS, Regex, and Memory

Summary

pg_clickhouse v0.3.2 updates the Postgres interface for querying ClickHouse, with changes centered on PostgreSQL 19 Beta1 support, TLS configuration, regular-expression pushdown, and memory consumption. The release adds CREATE SERVER options for forcing TLS or plaintext, selecting a minimum TLS version, and enabling ClickHouse native-protocol compression. Revised pushdown logic maps Postgres regular-expression flags to ClickHouse behavior, while regexp_match() can now be pushed down when its pattern has no capturing groups. Two memory issues were fixed: one involving unbuffered HTTP-driver queries and another involving repeated foreign scans such as parameterized inner scans in nested-loop joins. The minor update requires no reload, restart, or ALTER EXTENSION UPDATE, and also fixes empty-array ANY() errors on ClickHouse versions before 25.

Takeaways

1. 1

   The secure CREATE SERVER option supports on, off, and auto modes; min_tls_version accepts TLSv1 through TLSv1.3 and defaults to the TLS library's minimum.

2. 2

   Postgres and ClickHouse differ for m and p regular-expression behavior: ClickHouse equivalents do not prevent negated character classes such as [^xyz] from matching a newline, so those expressions require careful testing.

3. 3

   The release fixes memory problems associated with unbuffered HTTP-driver queries and repeated foreign scans, including parameterized inner scans in nested-loop joins.