确保索引不起作用 - MongoDB [英] Ensure index not working - MongoDB

问题描述

我正在尝试确保文档字段的索引，而不是
工作。 MongoDB版本是2.0.2。
这是非常基本的，不知怎的，我觉得我可能错过了
的东西或不！
能够插入3个带有相同空字符串的文档!!

I am trying to ensure index on a field of a document and its not working. MongoDB version is 2.0.2. This is very basic and somehow i'm feeling i might have missed something or not!!! Its able to insert 3 docs with same empty string !!

以下是详细信息：

> use testinsert
switched to db testinsert
> db.users.ensureIndex({ name : 1});
> doc = {
... name  : ""
... }
{ "name" : "" }
> doc
{ "name" : "" }
> db.users.stats();
{
       "ns" : "testinsert.users",
       "count" : 0,
       "size" : 0,
       "storageSize" : 8192,
       "numExtents" : 1,
       "nindexes" : 2,
       "lastExtentSize" : 8192,
       "paddingFactor" : 1,
       "flags" : 1,
       "totalIndexSize" : 16352,
       "indexSizes" : {
               "_id_" : 8176,
               "name_1" : 8176
       },
       "ok" : 1
}
> db.users.insert(doc);
> db.users.insert(doc);
> db.users.insert(doc);
> db.users.find();
{ "_id" : ObjectId("4f1980dc7e154e6702c4914c"), "name" : "" }
{ "_id" : ObjectId("4f1980dd7e154e6702c4914d"), "name" : "" }
{ "_id" : ObjectId("4f1980dd7e154e6702c4914e"), "name" : "" }
> db.users.ensureIndex({ name : 1});
> db.users.insert(doc);
> db
testinsert
> db.users.find();
{ "_id" : ObjectId("4f1980dc7e154e6702c4914c"), "name" : "" }
{ "_id" : ObjectId("4f1980dd7e154e6702c4914d"), "name" : "" }
{ "_id" : ObjectId("4f1980dd7e154e6702c4914e"), "name" : "" }
{ "_id" : ObjectId("4f1981557e154e6702c49150"), "name" : "" }
> version();
version: 2.0.2

有人可以澄清可能是什么问题！

can somebody pls clarify as to what might be the problem !

推荐答案

没有问题，你可以看到索引在那里。你期望它不允许重复元素？为此，您必须将唯一标志设置为true：

There are no problems, you can see that the index is there. You're expecting it not to allow duplicate elements? For that you have to set unique flag to true:

db.users.ensureIndex({ name : 1},{unique: true});

更新：使用 {unique：true}再次运行确保不起作用，你必须再次放弃 ensureIndex ：

UPDATE: running ensure once again with {unique: true} doesn't work, you have to drop and ensureIndex again:

db.users.dropIndex({name:1})
db.users.ensureIndex({ name : 1}, {unique:true, dropDups : true}); 

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