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MySQL Performance for Growing Web Applications
How to find slow queries, choose useful indexes, avoid N+1 reads, and keep database performance measurable.
By Junaid HossainJuly 5, 20267 min read
Measure before optimizing
Start with the slow query log, application traces, and EXPLAIN output. Optimizing queries that are already fast adds complexity without improving the user experience.
Build indexes for real queries
Indexes should follow the filters, joins, and ordering used by production queries. Composite index column order matters, so verify plans with representative data rather than guessing.
EXPLAIN ANALYZE
SELECT id, customer_id, total
FROM orders
WHERE customer_id = 42
AND status = 'paid'
ORDER BY created_at DESC
LIMIT 20;Control application query volume
A fast query repeated hundreds of times still creates a slow request. Eager-load known relationships, select only needed columns, and paginate large datasets.
- Detect and remove N+1 relationship queries
- Cache stable, expensive aggregates
- Move long reports to background jobs
- Monitor query count and latency after deployment