FirestoreException：后端结束监听流

Question

我正在尝试使用 Firestore 为集合设置实时侦听器。每当在集合中添加、修改或删除文档时，我都希望调用侦听器。我的代码目前适用于一个集合，但是当我在更大的集合上尝试相同的代码时，它会失败并出现错误：

监听失败：com.google.cloud.firestore.FirestoreException：后端结束监听流：数据存储操作超时，或数据暂时不可用。

这是我的实际监听器代码：

/**
 * Sets up a listener at the given collection reference. When changes are made in this collection, it writes a flat
 * text file for import into backend.
 * @param collectionReference The Collection Reference that we want to listen to for changes.
 */
public static void listenToCollection(CollectionReference collectionReference) {

    AtomicBoolean initialUpdate = new AtomicBoolean(true);

    System.out.println("Initializing listener for: " + collectionReference.getId());

    collectionReference.addSnapshotListener(new EventListener<QuerySnapshot>() {
        @Override
        public void onEvent(@Nullable QuerySnapshot queryDocumentSnapshots, @Nullable FirestoreException e) {
            // Error Handling
            if (e != null) {
                System.err.println("Listen failed: " + e);
                return;
            }

            // If this is the first time this function is called, it's simply reading everything in the collection
            // We don't care about the initial value, only the updates, so we simply ignore the first call
            if (initialUpdate.get()) {
                initialUpdate.set(false);
                System.out.println("Initial update complete...\nListener active for " + collectionReference.getId() + "...");
                return;
            }

            // A document has changed, propagate this back to backend by writing text file.
            for (DocumentChange dc : queryDocumentSnapshots.getDocumentChanges()) {

                String docId = dc.getDocument().getId();
                Map<String, Object> docData = dc.getDocument().getData();

                String folderPath = createFolderPath(collectionReference, docId, docData);

                switch (dc.getType()) {
                    case ADDED:
                        System.out.println("Document Created: " + docId);
                        writeMapToFile(docData, folderPath, "CREATE");
                        break;
                    case MODIFIED:
                        System.out.println("Document Updated: " + docId);
                        writeMapToFile(docData, folderPath, "UPDATE");
                        break;
                    case REMOVED:
                        System.out.println("Document Deleted: " + docId);
                        writeMapToFile(docData, folderPath, "DELETE");
                        break;
                    default:
                        break;
                }
            }

        }
    });
}

在我看来，集合太大，集合的初始下载超时。我可以使用某种解决方法来实时获取此集合的更新吗？

Answer 1

我联系了 Firebase 团队，他们目前正在就这个问题与我联系。同时，我能够通过基于 Last Updated 时间戳属性查询集合来减小侦听器的大小。我只查看最近更新的文档，并让我的应用在每次进行更改时更改此属性。