Slow database queries create cascading performance problems. A single inefficient query can bring applications to their knees under load. Systematic optimization using execution plans identifies bottlenecks, while indexing strategies and query rewrites deliver dramatic improvements.
Execution Plan Analysis
Execution plans reveal how databases process queries. Sequential scans on large tables indicate missing indexes. Nested loops with high row counts suggest join optimization opportunities. Sort operations on large datasets may benefit from pre-sorted indexes.
- Always analyze execution plans for slow queries before optimizing blindly
- Look for sequential scans on large tables—indexes likely help
- Check join order and methods for multi-table queries
- Identify sort operations that could use index ordering
- Monitor actual vs estimated row counts for plan accuracy
Indexing Strategies
Indexes accelerate reads but slow writes and consume storage. Create indexes supporting your query patterns. Composite indexes serve multiple columns efficiently when column order matches query predicates. Partial indexes reduce size by indexing only relevant rows.