How to optimize MySQL queries

· Category: SQL & Databases

Short answer

Optimize MySQL queries by analyzing execution plans, adding appropriate indexes, rewriting inefficient SQL, and tuning server configuration.

Steps

  1. Use EXPLAIN or EXPLAIN ANALYZE to identify full table scans.
  2. Add indexes on columns used in WHERE, JOIN, and ORDER BY.
  3. Avoid SELECT * and functions on indexed columns.
  4. Normalize large text columns and use covering indexes where possible.
  5. Tune innodb_buffer_pool_size and query_cache settings for the workload.

Tips

  • Enable the slow query log to find candidates for optimization.
  • Use composite indexes with columns in order of selectivity and query usage.

Common issues

  • Missing indexes on foreign keys cause slow joins.
  • Inefficient ORDER BY with LIMIT may create temporary tables and filesorts.r