Fix Query Issues
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Query Targeting alerts indicate inefficient query or queries.
Alert Conditions
You can configure the following alert conditions in the project-level alert settings page to trigger alerts.
Query Targeting: Scanned / Returned occurs if the number of index keys examined to fulfill a query relative to the actual number of returned documents meets or is above a certain threshold.
Query Targeting: Scanned Objects / Returned occurs if the number of documents examined to fulfill a query relative to the actual number of returned documents meets or is above a certain threshold.
Common Triggers
No index that supports a given query or queries.
Existing index can only partially support a query or queries.
Fix the Immediate Problem
The Performance Advisor provides the easiest and quickest way to create an index. The Performance Advisor monitors queries that MongoDB considers slow and recommends indexes to improve performance.
Click Create Index on a slow query for instructions on how to create the recommended index.
Note
It is possible to receive a Query Targeting alert for an inefficient query without receiving index suggestions from the Performance Advisor if the query exceeds the slow query threshold and the ratio of scanned to returned documents is greater than the threshold specified in the alert.
In addition, you can use the following resources to determine which query generated the alert:
The Real-Time Performance Panel monitors and displays current network traffic and database operations on machines hosting MongoDB in your MongoDB Atlas clusters.
The MongoDB logs maintain an account of activity, including queries, for each
mongodinstance in your MongoDB Atlas clusters.The cursor.explain() command for
mongoshprovides performance details for all queries.Query Insights monitors collection-level query latency.
The Data Profiler records operations that MongoDB Atlas considers slow when compared to average execution time for all operations on your cluster.
Note
Enabling the Database Profiler incurs a performance overhead.
Implement a Long-Term Solution
To learn more about query performance, see:
Monitor Your Progress
Cloud Manager provides the following methods to visualize query targeting:
Query Targeting metrics, which highlight high ratios of objects scanned to objects returned.
Query Insights, which monitors collection-level query latency.
The Profiler, which describes specific inefficient queries executed on the cluster.