About Query Analytics¶

Query Analytics (QAN) helps you find and fix slow queries. Use it to identify performance bottlenecks, understand query patterns, and track optimization progress.

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Stored metrics and Real-time QAN¶

Query Analytics offers two ways to analyze queries:

Stored metrics: Choose stored metrics when you want to analyze completed queries to identify patterns, find slow queries, and track optimization progress over time.
Real-time: Choose real-time when you need to identify problematic operations during an active incident.

Real-time vs. Stored metrics capabilities¶

Feature	Real-time Analytics (RTA)	Stored metrics (QAN)
Data type	Currently executing queries	Completed queries
Purpose	Live troubleshooting	Performance optimization
Time range	Live data (updates every 1-5 seconds)	Historical data (configurable retention)
Use case	Spot problematic operations during incidents	Analyze trends and optimize past performance
Database support	MongoDB (Technical Preview)	MySQL, PostgreSQL, MongoDB
Data retention	Temporary (refreshes with new data)	Persistent (stored for analysis)
Refresh rate	Live updates (1-5 seconds, configurable)	Historical snapshots
Query details	Raw operation data from `db.currentOp()` (no aggregation, grouping, or processing)	Aggregated metrics and query fingerprints
Best for	“What’s slowing down my database right now?”	“Which queries should I optimize?”

Requirements for Profiler¶

- Profiling enabled for Query Analytics
- Appropriate user roles: `clusterMonitor`, `read` (local), and custom monitoring roles. For MongoDB 8.0+: Additional `directShardOperations` role required for sharded clusters

### Requirements for Mongolog

- MongoDB configured to log slow operations to a file
- MongoDB server has write permissions to the log directory and file
- PMM agent has read permissions to the MongoDB log file
- Appropriate user roles: `clusterMonitor`, or custom monitoring roles (`getCmdLineOpts` privilege on `{ cluster: true }`)

Dashboard components¶

Query Analytics displays metrics in both visual and numeric form. Performance-related characteristics appear as plotted graphics with summaries.

Dashboard layout¶

The dashboard contains three panels:

Data retrieval delays¶

Query Analytics data retrieval is not instantaneous because metrics are collected once per minute. When collection delays occur, no data is reported and gaps will appear in the sparkline.

Label-based access control¶

Query Analytics integrates with PMM’s label-based access control (LBAC) to enforce data security and user permissions.

When LBAC is enabled:

users see only queries from databases and services permitted by their assigned roles
filter dropdown options are dynamically restricted based on user permissions
data visibility is controlled through Prometheus-style label selectors

Troubleshooting¶

If you experience Query Analytics performance issues in low-memory environments (less than 16 GB RAM), see ClickHouse memory issues.