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Avoid TOO_MANY_PARTS with async_insert

ClickHouse was originally designed to insert data in batches.

For engineers accustomed to other databases, it's a common mistake to send hundreds of individual inserts per second to ClickHouse and get a TOO_MANY_PARTS error. This error is ClickHouse telling us to throttle ingestion, as it can't keep up.

Until recently, you were required to solve this issue yourself, by buffering inserts and sending larger batches.

However, ClickHouse v21.11 introduced async_insert which enables ClickHouse to handle batching small inserts for you.


async_insert is disabled by default, so you must enable it to take advantage of this feature.

If you decide to use it you should also have a look at async_insert_threads, async_insert_max_data_size, async_insert_busy_timeout_ms and wait_for_async_insert.