We ran into some challenges with async inserts at highlight.io [2]. Namely, ClickHouse Cloud has an async flush size configured (that can't be changed AFAIK) that isn't large enough for our scale. Once you async insert more than can be flushed, you get back pressure on your application waiting to write while Clickhouse flushes the queue. We found that implementing our own batched flushing via kafka [3] is far more performant, allowing us to insert 500k+ RPS on the smallest cloud instance type.
We ran into some challenges with async inserts at highlight.io [2]. Namely, ClickHouse Cloud has an async flush size configured (that can't be changed AFAIK) that isn't large enough for our scale. Once you async insert more than can be flushed, you get back pressure on your application waiting to write while Clickhouse flushes the queue. We found that implementing our own batched flushing via kafka [3] is far more performant, allowing us to insert 500k+ RPS on the smallest cloud instance type.
[1] https://clickhouse.com/docs/en/optimize/asynchronous-inserts [2] https://github.com/highlight/highlight/tree/main [3] https://github.com/highlight/highlight/blob/4d28451b1935796d...