firebase - 为什么此Firebase ".indexOn"不起作用？

Question

所以我有这样的数据:

pushNotifications {
    -K - RwEgd541PIGNOXXUH: {
        message: "Xiaoyu Hugh Hou bid at $900 on your task: New P..."
        notifyId: "facebook:10100683829966199"
        relatedTask: "-Jzl8XKaxGCv19nIOChm"
        timestamp: 1443594566599
    } - K - RwpcBlQa04VJT4Bwm: {
        message: "Sam Feldt bid at $1100 on your task: New Post g..."
        notifyId: "google:1043268349966197"
        relatedTask: "-Jzl8XKaxGCv19nIOChm"
        timestamp: 1443594721963
    } - K - RwuM3 - 0 G0q9I96WHg: {
        message: "Sam Feldt bid at $600 on your task: NO Firebase..."
        notifyId: "facebook:10100683829966199"
        relatedTask: "-JzTSk2TIlO46oVqJ1Nn"
        timestamp: 1443594741347
    }
}

在我的代码中，我需要将下面的最新通知发送给某个“notifyId”。这是代码:

ref.child('pushNotifications')
   .orderByChild("notifyId")
   .limitToLast(1)
   .on("child_added", function (snapshot) {
       console.log("Found a new notification...");
       sendPush(snapshot.val());
   });

在我的Firebase安全规则中，我具有以下索引规则:

 "pushNotifications": {
      ".read": "auth != null",
      ".write": "auth != null",
      "$pushId": {
        ".indexOn": ["notifyId", "timestamp"],
      }
    },

这是Firebase文档在此处遵循的索引结构: docs

但是当我运行代码时，控制台仍会记录

FIREBASE WARNING: Using an unspecified index. Consider adding ".indexOn": "notifyId" at /pushNotifications to your security rules for better performance

自从我这样做以来，这没有任何意义。请帮忙!

Answer 1

您需要将.indexOn比您执行的操作高一级:

 "pushNotifications": {
    ".read": "auth != null",
    ".write": "auth != null",
    ".indexOn": ["notifyId", "timestamp"]
},

为了进行比较，请始终查看 Firebase documentation on indexes，它使用以下JSON示例:

"dinosaurs": {
  "lambeosaurus": {
    "height" : 2.1,
    "length" : 12.5,
    "weight": 5000
  },
  "stegosaurus": {
    "height" : 4,
    "length" : 9,
    "weight" : 2500
  }
}

使用此索引规则:

{
  "rules": {
    "dinosaurs": {
      ".indexOn": ["height", "length"]
    }
  }
}