MySQL 手册中的 dive into 该怎么理解?

2019-01-07 17:17:17 +08:00
 virus94

在看 mysql5.7 的手册,看到 Optimization 章节时,发现这一段

 • Otherwise, any index on col_name is nonunique and the optimizer can estimate the row count for each
range using dives into the index or index statistics.

With index dives, the optimizer makes a dive at each end of a range and uses the number of rows in the
range as the estimate. For example, the expression col_name IN (10, 20, 30) has three equality
ranges and the optimizer makes two dives per range to generate a row estimate. Each pair of dives yields
an estimate of the number of rows that have the given value.

  Index dives provide accurate row estimates, but as the number of comparison values in the expression
increases, the optimizer takes longer to generate a row estimate. Use of index statistics is less accurate
than index dives but permits faster row estimation for large value lists.

查了一下有道词典,dive 翻译为潜水,俯冲,知乎上有个 DBA 翻译了这个章节,也翻译成潜水,总感觉不对.

请教各位,这里面的 dive 和 dive into 该如何理解?

3452 次点击
所在节点    MySQL
3 条回复
mywaiting
2019-01-07 17:23:27 +08:00
dive into 理解为“深入”?
fkdog
2019-01-07 17:36:29 +08:00
不止 dive into,还有 dig into,
isrfr
2019-03-24 16:54:06 +08:00
植入?

这是一个专为移动设备优化的页面(即为了让你能够在 Google 搜索结果里秒开这个页面),如果你希望参与 V2EX 社区的讨论,你可以继续到 V2EX 上打开本讨论主题的完整版本。

https://www.v2ex.com/t/524708

V2EX 是创意工作者们的社区,是一个分享自己正在做的有趣事物、交流想法,可以遇见新朋友甚至新机会的地方。

V2EX is a community of developers, designers and creative people.

© 2021 V2EX