Home / Optimizations

SQL Optimizations

Browse our collection of SQL optimization examples with before and after comparisons.

01 Physical Storage Optimization

Optimize database performance by rearranging data on storage and using faster storage devices.
02 Basic Indexing

Learn how adding indexes can dramatically improve query performance.
03 Composite Indexes

Optimize multi-column queries with composite indexes.
04 JOIN Optimization

Optimize slow JOIN queries using proper join types and techniques.
05 Subquery to JOIN

Convert inefficient correlated subqueries to JOINs for better performance.
06 SELECT * Elimination

Improve performance by selecting only required columns.
07 Pagination with LIMIT

Optimize paginated queries using keyset pagination instead of OFFSET.
08 DISTINCT vs GROUP BY

Understand when to use DISTINCT vs GROUP BY for optimal query performance.
09 UNION vs UNION ALL vs OR

Choose between UNION, UNION ALL and OR for optimal query performance based on your conditions.
10 Database Normalization

Learn about database normalization forms: 1NF, 2NF, 3NF, and BCNF. Understand when to normalize and when to denormalize.
11 Query Sargability

Learn how to write sargable queries that can efficiently use indexes.
12 Function Order Optimization

Learn how the order of functions in WHERE clauses affects query performance.
13 SQLite Tips

SQLite-specific optimization tips including VACUUM and performance tuning.
14 Proper Query Execution Ordering

Understand the order in which SQL clauses are executed to write more efficient queries.
15 Temporary Tables

Learn when and how to use temporary tables for better query performance.
16 Subquery vs CTE vs Temp Table

Learn when to use subqueries, CTEs, or temporary tables for optimal query performance.