问题：原有的索引没有 unique 唯一属性，为其添加 unique 。
一、查询索引
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| mgset-44912522:PRIMARY> db.user.getIndexes()
[
{
"v" : 2,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "mydb.user"
},
{
"v" : 2,
"key" : {
"username" : 1
},
"name" : "username",
"ns" : "mydb.user"
}
]
|
接下来，给username索引增加唯一属性，要先删除旧索引，再重新建立新的索引。
二、删除索引
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| mgset-44912522:PRIMARY> db.user.dropIndex('username')
{
"nIndexesWas" : 3,
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1713167379, 1),
"signature" : {
"hash" : BinData(0,"sRHeElmSwQZdxoUt6OU0PIZhnOc="),
"keyId" : NumberLong("7316702510742241281")
}
},
"operationTime" : Timestamp(1713167379, 1)
}
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三、重建索引
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| mgset-44912522:PRIMARY> db.user.createIndex({ username: 1 }, { unique: true })
# 这个错误是由于数据中已经存在多个数据 { username: \"helloworld\" }，删除多余的保留一个即可。
{
"operationTime" : Timestamp(1713167425, 1),
"ok" : 0,
"errmsg" : "E11000 duplicate key error collection: mydb.user index: username_1 dup key: { username: \"helloworld\" }",
"code" : 11000,
"codeName" : "DuplicateKey",
"keyPattern" : {
"username" : 1
},
"keyValue" : {
"username" : "helloworld"
},
"$clusterTime" : {
"clusterTime" : Timestamp(1713167425, 1),
"signature" : {
"hash" : BinData(0,"Tbzv65r2RnDFtVf1NSsZHD+ptTU="),
"keyId" : NumberLong("7316702510742241281")
}
}
}
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数据删除之后，重新执行：
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| mgset-44912522:PRIMARY> db.user.createIndex({ username: 1 }, { unique: true })
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 2,
"numIndexesAfter" : 3,
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1713167572, 2),
"signature" : {
"hash" : BinData(0,"7baxP78Ao5NVroY+BdehOEhyrE4="),
"keyId" : NumberLong("7316702510742241281")
}
},
"operationTime" : Timestamp(1713167572, 2)
}
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四、再次查询索引
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| mgset-44912522:PRIMARY> db.user.getIndexes()
[
{
"v" : 2,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "mydb.user"
},
{
"v" : 2,
"unique" : true,
"key" : {
"username" : 1
},
"name" : "username_1",
"ns" : "mydb.user"
}
]
|