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Scaling request logging with ClickHouse, Kafka, and Vector

Great write-up!

I had a similar project back in August when I realised my DB's performance (Postgres) was blocking me from implementing features users commonly ask for (querying out to 30 days of historical uptime data).

I was already blown away at the performance (200ms to query what Postgres was doing in 500-600ms), but then I realized I hadn't put an index on the Clickhouse table. Now the query returns in 50-70ms, and that includes network time.

3 hours agorozenmd

Seems weird not to use Redis as the buffering layer + minutely cron job. Seems a lot simpler than installing Kafka + Vector.

an hour agomperham

BTW you could've used e.g. kittenhouse (https://github.com/YuriyNasretdinov/kittenhouse, my fork) or just a simpler buffer table, with 2 layers and a larger aggregation period than in the example.

Alternatively, you could've used async insert functionality built into ClickHouse: https://clickhouse.com/docs/optimize/asynchronous-inserts . All of these solutions are operationally simpler than Kafka + Vector, although obviously it's all tradeoffs.

2 hours agonasretdinov

There were a lot of simpler options that came to mind while reading through this, frankly.

But I imagine the writeup eschews myriad future concerns and does not entirely illustrate the pressure and stress of trying to solve such a high-scale problem.

Ultimately, going with a somewhat more complex solution that involves additional architecture but has been tried and tested by a 3rd party that you trust can sometimes be the more fitting end result. Assurance often weighs more than simplicity, I think.

2 hours agodevmor

While kittenhouse is, unfortunately, abandonware (even though you can still use it and it works), you can't say the same about e.g. async inserts in ClickHouse: it's a very simple and robust solution to tackle exactly the problem the PHP (and some other languages') backends often face when trying to use ClickHouse

2 hours agonasretdinov

Thanks for sharing. I really enjoyed the breakdown, and great to see small tech companies helping each other out!

2 hours agotlaverdure

Thanks for sharing I enjoyed reading this.

2 hours agofrenchmajesty

Currently at the millions stage with https://mailpace.com relying mostly on Postgres

Tbh this terrifies me! We don’t just have to log the requests but also store the full emails for a few days, and they can be up to 50 mib in total size.

But it will be exciting when we get there!

an hour agoalbertgoeswoof

How does Clickhouse compare to Druid, Pinot or Star Tree?

an hour agofnord77