Hacker News Reader

Comment by tempest_ | Hacker News Reader

This is nice because there are a lot of clickhouse fdw implementations and none of them are well maintained from what I can tell.

View on HN

Appreciate you chiming in! We evaluated almost all the FDWs and landed on clickhouse_fdw (built by Ildus) as the most mature option. However, it hadn’t been maintained since 2020. We used it as the base, and the goal is to take it to the next level.

Our main focus is comprehensive pushdown capabilities. It was very surprising to see how much the Postgres FDW framework has evolved over the years and the number and types of hooks it now provides for push down. This is why we decided to lean into FDW than build an extension bottoms up. But we may still do that within pg_clickhouse for a few features, wherever FDW framework becomes a restriction.

We’ve made notable progress over the last few months, including support for pushdown of custom aggregations and SEMI JOINs/basic subqueries. Fourteen of twenty-two TPCH queries are now fully pushdownable.

We’ll be doubling down to add pushdown support for much more complex queries, CTEs, window functions, and more. More on the future here - https://github.com/ClickHouse/pg_clickhouse?tab=readme-ov-fi... All with the goal of enabling users to build fast analytics from the Postgres layer itself but still using the power of ClickHouse!

>All with the goal of enabling users to build fast analytics from the Postgres layer itself but still using the power of ClickHouse!

That would be incredible! So many times I want to reach for ClickHouse but whatever company I'm at has so much inertia built into PG. Pleease add CTE support.

And yes I'm aware of PeerDB or whatever that project is called. This is still or even more helpful.

You're replying to the CEO of PeerDB. We recognize CDC is only one tool in the integration toolbox, which is why we're prioritizing this

I shouldn't be so flippant on here, of course I'm talking to the guy who wakes up and hears this every day.

I really appreciate the work that he and y'all are doing on both sides of the equation, it's great for every org that wants to use ClickHouse but can't.

Totally! Making things way easier on the app and query side is very important, which is why we plan to invest heavily in this going forward.

With respect to data replication, it gets really hard and has its challenges as data sizes grow - reliably moving tens of terabytes at speed, handling intricate quirks around replication slots, enterprise-grade observability etc. PeerDB/ClickPipes is designed to solve these problems. I wrote a blog post covering this in more detail here: https://clickhouse.com/blog/postgres-cdc-year-in-review-2025

That said, point taken - we will ensure query and app migration is seamless as well and reduce friction in integrating Postgres and ClickHouse. pg_clickhouse is a step in that direction! :)

(Note: we work closely with the clickhouse team so this is not to intended to detract from their launch, simply to point out maintained options.)

Our CH wrapper is actively maintained, with push down, parameterized views, and async streaming: https://supabase.github.io/wrappers/catalog/clickhouse/

We see a lot of companies choosing CH with PG - it’s fantastic

Thank you, Paul! Great to see Supabase wrappers evolve. I really love the async streaming feature. It helps address use cases involving (reliably) moving larger datasets from ClickHouse to Postgres for supporting (stricter) transactional workloads.

Very excited to continue working closely to further integrate these amazing open source database technologies and make it easier for users. :)

Reply on news.ycombinator.com