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MongoDBで検索する時にindexを強制する

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やりかた

ヘルパーメソッドのhelp()を使う場合はこう。

db.users.find().hint( { age: 1 } )

$hintオペレータを使う場合はこう。

db.users.find()._addSpecial( "$hint", { age : 1 } )
db.users.find( { $query: {}, $hint: { age : 1 } } )

上記は、usersコレクションのすべてのドキュメントをageフィールドをindexにして検索するという意味。

{ age: 1 }1は昇順という意味、降順にしたい場合は-1にすればよいです。

本当にそうなっているのか調べたい時

例えば$explainオペレータを使って以下のように書けばOK。

db.users.find( { $query: {}, $hint: { age : 1 }, $explain: 1 } )

参考

* MongoDB Reference: hint()
* MongoDB Reference: $hint

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