But before I do that, I’d like to be more confident that this approach really can handle most real-world scenarios.
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.
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未来的知识工作者将不再需要学习任何软件的操作界面。
This has led to a field whose standard practices are a cluster of bad habits and superstition. Web development is now especially notorious for completely disregarding accessibility, user device capabilities, and regulations. Most of the ideas of user-centred design are alien to modern developers. Misconceptions about test-driven development and pair programming abound. Code review is the norm even though it’s largely useless as practised.
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