假设这是代表客户的文档。
{
company_name: 'corporate ltd.',
pocs: [
{name: 'Paul', email: 'paul@corporate.com'},
{name: 'Jessica', email: 'jessica@corporate.com'}
]
}
我想为 pocs.email
定义一个唯一的索引,
因此我执行了以下命令:
db.things.ensureIndex({"pocs.email": 1}, {unique: true})
奇怪的是,当尝试添加一个拥有已经存在于另一家公司中的电子邮件的poc时,Mongo会拒绝该操作,遵循唯一索引约束。
也就是说,以下情况不允许存在:
{
company_name: 'corporate ltd.',
pocs: [
{name: 'Paul', email: 'paul@corporate.com'},
{name: 'Jessica', email: 'jessica@corporate.com'}
]
},
{
company_name: 'contoso llc',
pocs: [
{name: 'Paul', email: 'paul@corporate.com'},
]
}
这很好。然而,在同一文档中存在重复的poc是可能的,例如:
{
company_name: 'corporate ltd.',
pocs: [
{name: 'Paul', email: 'paul@corporate.com'},
{name: 'Paul', email: 'paul@corporate.com'},
{name: 'Jessica', email: 'jessica@corporate.com'}
]
},
以下是我使用的CLI命令序列:
> version()
version: 2.0.2
>
> use test
switched to db test
> db.test.ensureIndex({"poc.email": 1}, {unique: true})
>
> db.test.insert({company: "contoso", poc: [{email: 'me@comapny.com'}]})
> db.test.insert({company: "contoso", poc: [{email: 'me@comapny.com'}]})
E11000 duplicate key error index: test.test.$poc.email_1 dup key: { : "me@comapny.com" }
> ({company: "contoso", poc: [{email: 'me.too@comapny.com'}, {email: 'me.too@company.com'}]})
>
>
> db.test.find()
{ "_id" : ObjectId("4f44949685926af0ecf9295d"), "company" : "contoso", "poc" : [ { "email" : "me@comapny.com" } ] }
{ "_id" : ObjectId("4f4494b885926af0ecf9295f"), "company" : "contoso", "poc" : [ { "email" : "me.too@comapny.com" }, { "email" : "me.too@company.com" } ] }
此外,这种情况会发生在
插入
或更新
时。> db.test.update({"_id" : ObjectId("4f44949685926af0ecf9295d")}, {$push: { poc: {email: 'me@company.com'}}})
> db.test.find()
{ "_id" : ObjectId("4f4494b885926af0ecf9295f"), "company" : "contoso", "poc" : [ { "email" : "me.too@comapny.com" }, { "email" : "me.too@company.com" } ] }
{ "_id" : ObjectId("4f44949685926af0ecf9295d"), "company" : "contoso", "poc" : [ { "email" : "me@comapny.com" }, { "email" : "me@company.com" }, { "email" : "me@company.com" } ] }
>
这是一个bug还是我在文档中忽略的设计特性?