What are the performance matrices used in MongoDB Query Performance Troubleshooting?

MongoDB offers several performance metrics that are crucial for troubleshooting query performance issues. Here are the key metrics used in MongoDB query performance troubleshooting:

Query Execution Metrics

• Query Targeting: This metric helps identify if queries are using indexes effectively[2].
• Execution Time: Measures the latency of read and write operations. Read operations taking more than 100ms are generally considered slow[3].
• Scanned vs. Returned Ratio: Indicates how many documents were scanned to return the result set. A high ratio suggests inefficient queries or missing indexes[4].

Resource Utilization Metrics

• CPU Utilization: High CPU usage can indicate complex queries or insufficient indexing[2].
• Memory Utilization: Monitors the usage of RAM, which is crucial for caching frequently accessed data[2].
• Storage Metrics: Tracks disk I/O and storage capacity[2].

Database Operation Metrics

• Operation Counts: Tracks the number of insert, query, update, and delete operations per second[3].
• Connections: Monitors the number of active client connections[3].

Index Performance Metrics

• Index Usage: Measures how frequently indexes are used in queries[1].
• Index Size: Tracks the size of indexes, which can impact write performance if too large[4].

Replication Metrics

• Replication Lag: Measures the delay between operations on the primary and their replication to secondaries[4].

Cache Performance

• Cache Hit Ratio: Indicates how often requested data is found in memory cache versus disk[9].
• Dirty Cache Percentage: Shows the proportion of modified data in the cache waiting to be written to disk[9].

Latency Metrics

• Read Latency: Measures the time taken for read operations[11].
• Write Latency: Tracks the duration of write operations[11].

Profiler Metrics

• Slow Query Log: Captures queries that exceed a specified execution time threshold[6].
• Query Shapes: Provides information on common query patterns and their performance[6].

By monitoring these metrics, database administrators can identify performance bottlenecks, optimize query execution, and ensure efficient resource allocation for MongoDB deployments.

Sources
[1] Track and Troubleshoot MongoDB Performance With Datadog ... https://www.datadoghq.com/blog/mongodb-database-monitoring/
[2] How to Monitor MongoDB Performance Metrics Using the ... - GeoPITS https://www.geopits.com/blog/mongodb-performance-metrics.html
[3] MongoDB Monitoring | Beginner's Guide to MongoDB performance ... https://signoz.io/blog/mongodb-monitoring/
[4] MongoDB Performance Tuning Questions https://www.mongodb.com/developer/products/mongodb/performance-tuning-tips/
[5] How to Optimize MongoDB Queries for Performance? https://www.geeksforgeeks.org/how-to-optimize-mongodb-queries-for-performance/
[6] Analyze Query Performance - MongoDB Manual v8.0 https://www.mongodb.com/docs/manual/tutorial/evaluate-operation-performance/
[7] How to Troubleshoot Slow Queries in MongoDB - Netdata https://www.netdata.cloud/academy/how-to-troubleshoot-slow-queries-in-mongodb/
[8] How do you troubleshoot MongoDB performance issues? - Dragonfly https://www.dragonflydb.io/faq/mongodb-performance-troubleshooting
[9] Review Available Metrics - MongoDB Atlas https://www.mongodb.com/docs/atlas/review-available-metrics/
[10] How To Monitor MongoDB And What Metrics To Monitor https://www.mongodb.com/resources/products/capabilities/how-to-monitor-mongodb-and-what-metrics-to-monitor
[11] Monitoring MongoDB Performance Metrics (WiredTiger) - Datadog https://www.datadoghq.com/blog/monitoring-mongodb-performance-metrics-wiredtiger/
[12] How To Monitor MongoDB's Performance - DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-monitor-mongodb-s-performance
[13] Optimize Query Performance - MongoDB Manual v8.0 https://www.mongodb.com/docs/manual/tutorial/optimize-query-performance-with-indexes-and-projections/