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As well as the poor selection of a partition key, this issue can manifest itself as a result of many small inserts. Each INSERT into ClickHouse results in an insert block being converted to a part. To keep the number of parts manageable, users should therefore buffer data client-side and insert data as batches - at a minimum 1,000 rows per insert, although batch sizes of 10,000 to 100,000 rows are optimal. If client-side buffering is not possible, users can defer this task to ClickHouse through async inserts. In this case, ClickHouse will buffer inserts in memory before flushing them as a single batched part into the underlying table. The flush is triggered when a configurable threshold is met: a buffer size limit (async_insert_max_data_size, default 1MB), a time threshold (async_insert_busy_timeout_ms, default 1 second), or a maximum number of queued queries (async_insert_max_query_number, default 100). Since data is held in memory until flush, it is important to set wait_for_async_insert=1 (the default) so that the client receives acknowledgement only after data has been safely written to disk, avoiding silent data loss in the event of a server crash before a flush.
。新收录的资料是该领域的重要参考
这是一份力透纸背的民生成绩单：
短短几天，项目新增Star就超过了2万！
DKbench runs the benchmark suite single-threaded and multi-threaded (2 threads in this comparison as we use 2x vCPU instances) and calculates a scalability percentage. The benchmark obviously uses highly parallelizable workloads (if that's not what you are running, you'd have to rely more on the single-thread benchmarking). In the following graph 100% scalability means that if you run 2 parallel threads, they will both run at 100% speed compared to how they would run in isolation. For systems where each vCPU is 1 core (e.g. all ARM systems), or for "shared" CPU systems where each vCPU is a thread among a shared pool, you should expect scalability near 100% - what is running on one vCPU should not affect the other when it comes to CPU-only workloads.