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Comment by lima | Hacker News Reader

And apparently ClickHouse out-performs MemSQL: https://clickhouse.yandex/benchmark.html

Has anyone here experience with ClickHouse?

No experience, but did a thorough read through of the docs. One thing to keep in mind about clickhouse is that their replication guarantees aren't very strong. From the docs: "There are no quorum writes. You can't write data with confirmation that it was received by more than one replica."

That's pretty troubling, but at least they're open about it. That said their performance claims are pretty spectacular, and it seems solidly engineered. Further if you're not planning on using replication it certainly seems interesting. I'd be curious to hear about someone's production experience as well, since the list of companies running it seems rather thin.

(ClickHouse dev here)

Yes, replication in ClickHouse is asynchronous by default. For intended use cases (OLAP queries aggregating data from many rows) data that is a few seconds stale is usually okay. In a serious production deployment you absolutely should enable replication, otherwise you risk losing all your data, not just last couple of seconds of inserts.

That said, sometimes synchronous replication is necessary despite the latency penalty that comes with it. This feature is actually implemented but not yet considered ready for prime time.

We have several years of production experience with ClickHouse (as a DBMS powering Yandex.Metrica - second largest web analytics system in the world). If you have questions - just ask.

We're using it internally, and also for a relatively small customer-facing analytics API, on the order of 10-30 nodes.

It's been good so far. Good support from the maintainers, too.

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