有很多指数的缺点是什么？ [英] What are the disadvantages of having many indices?

问题描述

我最近通过给SQLite一个很好的索引来处理一个复杂的查询一个数量级。像这样的结果让我想知道我是否应该索引很多其他字段通常用于JOINS或ORDER BY子句。但我不想得到过分热情，让我反感：我假设有一些原因不创建索引，或每个字段将被默认索引。

I recently sped up a complicated query by an order of magnitude by giving SQLite a good index to work with. Results like this make me wonder if I should index a lot of other fields that are commonly used for JOINs or ORDER BY clauses. But I don't want to get overzealous and have it backfire on me: I assume there must be some reasons not to create indices, or every field would be indexed by default.

我在这种情况下使用SQLite，但是当然也欢迎DBMS-agnostic的建议。

I'm using SQLite in this case, but of course DBMS-agnostic advice is welcome as well.

推荐答案

索引会减慢插入和更新（这可能会成为一个非常严重的问题与锁定）和成本磁盘空间。这是很多。

Indexes slow down inserts and updates (which can become a really serious issue with locking) and cost disk space. That's pretty much it.

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