Fundamentals of Query Optimization
graph TD
A[Query Performance Tuning] --> B[Index Strategy]
A --> C[Query Design]
A --> D[Resource Management]
A --> E[Monitoring]
Query Analysis Techniques
1. Explain() Method Analysis
Metric |
Description |
Optimization Potential |
COLLSCAN |
Full Collection Scan |
High Performance Impact |
IXSCAN |
Index Scan |
Moderate Performance |
COVERED |
Fully Indexed Query |
Optimal Performance |
Example Explain Analysis
## Analyze query performance
db.users.find({
"registrationDate": {
$gte: ISODate("2023-01-01")
}
}).explain("executionStats")
Advanced Query Optimization Strategies
Index Intersection
## Create multiple indexes
db.transactions.createIndex({"userId": 1})
db.transactions.createIndex({"timestamp": 1})
## Optimize complex queries
db.transactions.find({
"userId": "user123",
"timestamp": { $gte: new Date() }
})
Query Projection Techniques
## Limit returned fields
db.users.find(
{ "registrationDate": { $gte: ISODate("2023-01-01") } },
{
"email": 1,
"registrationDate": 1,
"_id": 0
}
)
MongoDB Profiler Configuration
## Enable database profiling
db.setProfilingLevel(1, { slowms: 100 })
## View slow queries
db.system.profile.find({
millis: { $gt: 100 }
}).sort({ millis: -1 })
Compound Index Optimization
## Create efficient compound index
db.orders.createIndex({
"customerId": 1,
"orderDate": -1,
"totalAmount": 1
})
Query Optimization Checklist
- Use selective indexes
- Avoid unnecessary sorting
- Limit result set size
- Use proper projection
- Leverage index coverage
At LabEx, we recommend continuous performance monitoring and iterative query refinement to maintain optimal database performance.
Metric |
Significance |
Query Execution Time |
Primary Performance Indicator |
Index Usage Percentage |
Indexing Efficiency |
Scan Depth |
Query Complexity |
Advanced Techniques
Aggregation Pipeline Optimization
## Optimize aggregation queries
db.sales.aggregate([
{ $match: {
"date": { $gte: ISODate("2023-01-01") }
}},
{ $group: {
_id: "$region",
totalSales: { $sum: "$amount" }
}},
{ $sort: { totalSales: -1 } }
])
Conclusion
Effective query performance tuning requires a holistic approach combining strategic indexing, query design, and continuous monitoring.