Primary keys are rightly the first tool users turn to when needing to accelerate queries. However, tables are limited to a single primary key, and query access patterns can render this ineffective i.e., for diverse use cases, queries which cannot exploit the primary key efficiently are inevitable. In these cases ClickHouse can be forced to perform a full table scan of each column when applying a WHERE clause condition. Often this will still be sufficiently fast, but in some cases users reach for data skipping indices, hoping to accelerate these queries easily.
↓ 1 │ . │ . │ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 7 │ 8 │
。关于这个话题，新收录的资料提供了深入分析
Active noise cancellation that still needs work
正在改变与想要改变世界的人，都在 虎嗅APP
赫格塞思和美军参谋长联席会议主席凯恩当天在五角大楼举行联合新闻发布会。赫格塞思说，美军的行动目标非常明确，即摧毁伊朗的进攻性导弹、导弹生产设施及其海军和其他安全基础设施，“这样他们就永远无法拥有核武器”。