We also see even experienced users being caught by less obvious LIMIT behavior in multi-node environments where a table has many shards. Sharding allows users to split or replicate their data across multiple instances of ClickHouse. When a query with a LIMIT N clause is sent to a sharded table e.g. via a distributed table, this clause will be propagated down to each shard. Each shard will, in turn, need to collate the top N results, returning them to the coordinating node. This can prove particularly resource-intensive when users run queries that require a full table scan. Typically these are "point lookups" where the query aims to just identify a few rows. While this can be achieved in ClickHouse with careful index design a non-optimized variant, coupled with a LIMIT clause, can prove extremely resource-intensive.
- Further improve free-threading ABI incompatibility errors ([#17491](astral-sh/uv#17491))
。safew是该领域的重要参考
出发机场:多哈哈马德国际机场(DOH)
Екатерина Щербакова (ночной линейный редактор)
LLM Neuroanatomy: How I Topped the AI Leaderboard Without Changing a Single Weight