Command Monitoring

Overview

This guide shows you how to use the Go driver to monitor the outcome of commands that the driver sends to your MongoDB deployment.

You might use information about command events in your application to understand changes in query performance or resolve bottlenecks.

Subscribe to Events

You can access details about command events by subscribing to them in your application. The following example demonstrates how to subscribe to the CommandStartedEvent event by instantiating a CommandMonitor and connecting to a deployment:

var eventArray []*event.CommandStartedEvent
cmdMonitor := &event.CommandMonitor{
    Started: func(ctx context.Context, e *event.CommandStartedEvent) {
        eventArray = append(eventArray, e)
    },
}
clientOpts := options.Client().ApplyURI(uri).SetMonitor(cmdMonitor)
client, err := mongo.Connect(clientOpts)

Event Descriptions

You can subscribe to one or more of the following command monitoring events:

Example Event Documents

The following sections show sample output for each type of command monitoring event.

*event.CommandStartedEvent
{
    "Command": "...",
    "DatabaseName": "...",
    "CommandName": "...",
    "RequestID": ...,
    "ConnectionID": "...",
    "ServerConnectionID": ...,
    "ServiceID": "..."
}

*event.CommandSucceededEvent
{
    "DurationNanos": 38717583,
    "Duration": 38717583,
    "CommandName": "insert",
    "RequestID": 13,
    "ConnectionID": "...",
    "ServerConnectionID": ...,
    "ServiceID": null,
    "Reply": "..."
}

*event.CommandFailedEvent
{
    "DurationNanos": 38717583,
    "Duration": 38717583,
    "CommandName": "insert",
    "RequestID": 13,
    "ConnectionID": "...",
    "ServerConnectionID": ...,
    "ServiceID": null,
    "Failure": "..."
}

Additional Information

To learn more about monitoring a MongoDB deployment, see the How to Monitor MongoDB article.

To learn more about performing MongoDB operations, see the CRUD Operations guides.