What methods can be used to improve query performance in a database?

To improve query performance in a database, the following approaches can be used:

• Indexing: creating indexes on columns frequently used in WHERE or JOIN conditions.
• Query optimization: rewriting the query to reduce the number of operations, using more efficient JOINs, avoiding SELECT *.
• Caching: caching query results if the data does not change often.
• Parameterizing queries: helps the query planner reuse execution plans.
• Using prepared statements to reduce overhead.
• Analyzing the execution plan: studying EXPLAIN PLAN to identify bottlenecks.
• Minimizing data transfer volume: selecting only necessary fields and using pagination.

Example of indexing in SQL:

CREATE INDEX idx_user_email ON users(email);