Mongo唯一索引不区分大小写 [英] Mongo unique index case insensitive

问题描述

@CompoundIndexes({
    @CompoundIndex(name = "fertilizer_idx",
        unique = true,
        def = "{'name': 1, 'formula': 1, 'type': 1}")
})
public class Fertilizer extends Element implements Serializable {
//class stuff
}

是否可以创建不区分大小写的索引?现在，它在NAME和NAMe之间有所区别.保存第二个字段的小写(或大写)对我来说是不可能的.

Is it possible to create the index case insensitive? Right now it is differentiating from NAME to NAMe. Saving a second field lowercase (or uppercase) is not a possibility for me.

谢谢， 佩德罗

推荐答案

MongoDB 3.4版之前的版本，我们无法创建不区分大小写的索引 .

Prior of MongoDB version 3.4 we were unable to create index with case insensitive.

3.4版中的collation选项允许用户为字符串比较指定特定于语言的规则，例如字母大写和重音符号的规则.

In version 3.4 has collation option that allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

排序规则选项具有以下语法:

The collation option has the following syntax:

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

其中区域设置字段为强制；所有其他字段均为可选.

where the locale field is mandatory; all other fields are optional.

要创建不区分大小写的索引，我们需要使用必填字段 locale 和 strength 字段来进行字符串比较级别. strength允许值范围为 1-5 . 了解有关整理的更多信息

To create index with case insensitive we need to use mandatory field locale and strength field for string comparison level. strength allows value rage 1 - 5. read more about collation

strength属性确定整理或匹配文本时是否考虑重音或大小写

示例:

如果 strength = 1 ，则 role = Role =rôle

如果 strength = 2 ，则 role = Role<罗勒(Rôle)

如果 strength = 3 ，则角色<角色<角色

比较级文档

因此，我们需要使用strength=2创建索引.像:

So we need to use strength=2 to create index. like:

db.collectionName.createIndex(
  { name: 1, formula: 1, type: 1 },
  { 
    name: "fertilizer_idx",
    collation: {locale: "en", strength: 2},
    unique: true
  }
)

NB :collation选项不适用于文本索引.

N.B: collation option is not available for text indexes.

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