Analyze Query Performance
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MongoDB provides several ways to examine the performance of your workload, allowing you to understand query performance and identify long-running queries. Understanding query performance helps you build effective indexes and ensure your application runs critical queries efficiently.
Identify Slow Queries
Use the following methods to identify slow queries that occur on your deployment.
Performance Overview
The following methods provide overviews of your deployment's performance. Use these methods to determine if there are performance issues that need to be addressed:
Method | Availability | Description |
|---|---|---|
Use the Atlas Performance Advisor | M10+ Atlas clusters | The Atlas Performance Advisor monitors slow queries and suggests
new indexes to improve performance. For more information, see
Monitor and Improve Slow Queries. |
Check ongoing operations in Atlas | M10+ Atlas clusters | You can use the Atlas Real-Time Performance Panel (RTPP) to see current network
traffic, database operations, and hardware statistics. |
Check ongoing operations locally | Atlas clusters and self-hosted deployments | The You can also use the |
Check server metrics | Atlas clusters and self-hosted deployments | For Atlas clusters, you can view cluster metrics to identify performance issues. For self-hosted deployments, the |
View common query shapes | Atlas clusters and self-hosted deployments | The $queryStats aggregation stage returns information
about common query shapes. $queryStats provides a holistic
view of the kinds of queries being run on your deployment. |
View index statistics | Atlas clusters and self-hosted deployments | The $indexStats aggregation stage returns information
about your collection's indexes and how often individual indexes
are used. Use $indexStats to identify unused indexes that can
be removed to improve write performance. |
Analyze a Slow Query
Use these methods to analyze a slow query and determine the cause of poor performance:
Method | Availability | Description |
|---|---|---|
Use the Atlas Query Profiler | M10+ Atlas clusters | The Atlas Query Profiler shows long-running operations and
performance statistics. For more information, see
Monitor Query Performance. |
Enable the Database Profiler | Atlas clusters and self-hosted deployments | When enabled, the database profiler stores information about slow
queries in the For more information, see Database Profiler. |
View slow queries in the diagnostic log | Atlas clusters and self-hosted deployments | MongoDB logs queries that exceed the slow operation threshold (default 100 milliseconds) in the diagnostic logs. Check the diagnostic logs to identify problematic queries and see which queries would benefit from indexes. |
View explain results | Atlas clusters and self-hosted deployments | Query explain results show information on the query plan and execution statistics. You can use explain results to determine the following information about a query:
To view explain results, use the following methods:
To learn about explain results output, see Explain Results and Interpret Explain Plan Results. |
Perform Advanced Query Analysis
The following methods are suited for deeper investigation of problematic queries, and can provide fine-grained performance insights:
Method | Availability | Description |
|---|---|---|
View plan cache statistics | Atlas clusters and self-hosted deployments | The The plan cache contains query plans that the query planner uses to efficiently complete queries. Generally, the plan cache should contain entries for your most commonly-run queries. |