Firestore在获取数据方面性能缓慢 [英] Firestore slow performance issue on getting data

问题描述

使用Firestore时，性能问题比较慢，而检索存储在文档中的基本数据与实时数据库相比只有1/10的比例。

使用Firestore第一次调用时平均需要3000毫秒

  this.db.collection（'testCol'）
 .doc （'testDoc'）
 .valueChanges（）。forEach（（data）=> {
 console.log（data）; // 3000 ms later 
}）; 
  

使用实时数据库，在第一次调用时平均需要300 ms

  this.db.database.ref（'/ test'）。once（'value'）。then（data => {
 console.log（data）; // 300ms later 
}）; 
  

这是网络控制台的屏幕截图：

$ b 结果 - 已启用磁盘持久性：

$ b

数据结构

I'm having slow performance issues with Firestore while retrieving basic data stored in a document compared to the realtime database with 1/10 ratio.

Using Firestore, it takes an average of 3000 ms on the first call

 this.db.collection(‘testCol’)
   .doc(‘testDoc’)
   .valueChanges().forEach((data) => {
     console.log(data);//3000 ms later
 });

Using the realtime database, it takes an average of 300 ms on the first call

 this.db.database.ref(‘/test’).once(‘value’).then(data => {
     console.log(data); //300ms later
 });

This is a screenshot of the network console :

I'm running the Javascript SDK v4.50 with AngularFire2 v5.0 rc.2.

Did anyone experience this issue ?

解决方案

I've also discovered Firestore to be much slower than Realtime DB, especially when reading from lots of documents.

Updated tests (with latest iOS Firestore SDK v0.9.0):

I set up a test project in iOS Swift using both RTDB and Firestore and ran 100 sequential read operations on each. For the RTDB, I tested the observeSingleEvent and observe methods on each of the 100 top level nodes. For Firestore, I used the getDocument and addSnapshotListener methods at each of the 100 documents in the TestCol collection. I ran the tests with disk persistence on and off. Please refer to the attached image, which shows the data structure for each database.

I ran the test 10 times for each database on the same device and a stable wifi network. Existing observers and listeners were destroyed before each new run.

Realtime DB observeSingleEvent method:

func rtdbObserveSingle() {

    let start = UInt64(floor(Date().timeIntervalSince1970 * 1000))
    print("Started reading from RTDB at: \(start)")

    for i in 1...100 {
        Database.database().reference().child(String(i)).observeSingleEvent(of: .value) { snapshot in
            let time = UInt64(floor(Date().timeIntervalSince1970 * 1000))
            let data = snapshot.value as? [String: String] ?? [:]
            print("Data: \(data). Returned at: \(time)")
        }
    }
}

Realtime DB observe method:

func rtdbObserve() {

    let start = UInt64(floor(Date().timeIntervalSince1970 * 1000))
    print("Started reading from RTDB at: \(start)")

    for i in 1...100 {
        Database.database().reference().child(String(i)).observe(.value) { snapshot in
            let time = UInt64(floor(Date().timeIntervalSince1970 * 1000))
            let data = snapshot.value as? [String: String] ?? [:]
            print("Data: \(data). Returned at: \(time)")
        }
    }
}

Firestore getDocument method:

func fsGetDocument() {

    let start = UInt64(floor(Date().timeIntervalSince1970 * 1000))
    print("Started reading from FS at: \(start)")

    for i in 1...100 {
        Firestore.firestore().collection("TestCol").document(String(i)).getDocument() { document, error in

            let time = UInt64(floor(Date().timeIntervalSince1970 * 1000))
            guard let document = document, document.exists && error == nil else {
                print("Error: \(error?.localizedDescription ?? "nil"). Returned at: \(time)")
                return
            }
            let data = document.data() as? [String: String] ?? [:]
            print("Data: \(data). Returned at: \(time)")
        }
    }
}

Firestore addSnapshotListener method:

func fsAddSnapshotListener() {

    let start = UInt64(floor(Date().timeIntervalSince1970 * 1000))
    print("Started reading from FS at: \(start)")

    for i in 1...100 {
        Firestore.firestore().collection("TestCol").document(String(i)).addSnapshotListener() { document, error in

            let time = UInt64(floor(Date().timeIntervalSince1970 * 1000))
            guard let document = document, document.exists && error == nil else {
                print("Error: \(error?.localizedDescription ?? "nil"). Returned at: \(time)")
                return
            }
            let data = document.data() as? [String: String] ?? [:]
            print("Data: \(data). Returned at: \(time)")
        }
    }
}

Each method essentially prints the unix timestamp in milliseconds when the method starts executing and then prints another unix timestamp when each read operation returns. I took the difference between the initial timestamp and the last timestamp to return.

RESULTS - Disk persistence disabled:

RESULTS - Disk persistence enabled:

Data Structure:

When the Firestore getDocument / addSnapshotListener methods get stuck, it seems to get stuck for durations that are roughly multiples of 30 seconds. Perhaps this could help the Firebase team isolate where in the SDK it's getting stuck?

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