Марина Совина (ночной редактор)
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.。关于这个话题，whatsapp提供了深入分析
。谷歌是该领域的重要参考
但以色列模式也有短板——他们的研发目标往往是大公司收购。所以他们只做到“概念验证”，只研究大公司的需求，也就是所谓“从I到T”（从想法到技术），至于“从T到P”（从技术到产品）的阶段，他们不怎么考虑。
"We'll have to be mindful that in September we may be looking at having to spend twice as much to fill the tank up because I don't see the prices coming down in a sustained way."，更多细节参见WhatsApp Web 網頁版登入