Live Queries Dashboard

Live Queries Summary

This is a set of important metrics of your app's Live Queries. It includes following metrics:

Fetched Documents

This is the number of documents fetched from MongoDB via observers. Meteor fetches documents from MongoDB in a few different cases. Here are some of them:

Observer Changes

Once an observer is created, it’ll trigger events in a few different scenarios. Here's a list of those event types:

Oplog Notifications

Meteor watches the MongoDB oplog to observe changes happening in the MongoDB. If something happens in the DB, Meteor will receive it as a notification. The notification is attached to a collection. Then, Meteor will forward this notification to most of the observers created for that collection.

There are few different types of oplog notifications. They are:

Meteor will receive all these notification regardless of whether it has a related observer or not.

Total/Reused Observer Handlers

When a new Live Query is created, it’ll create a new observer that watches the DB for changes. If there is an observer already created for the query, Live Query won’t create a new observer. Instead, it’ll reuse an existing observer.

There is always a handler that sits between the Live Query and the observer.

If the reused count is close to total count, that means Live Queries have created a fewer number of actual observers, which is the ideal case.

Check this guide to learn how to increase the Reused Observer Handlers count.

Live Query Publication Breakdown

This is a breakdown of publications sorted by the different metrics related to Live Queries. They include:

This content originally appeared in the Kadira Knowledge Base.