SQLite ORDER BY Optimization

SQLite ORDER BY Optimization is a SQL statement in the SQLite Specific category. SQLite uses indexes for ORDER BY when possible. Creating the right index can eliminate explicit sorting (filesort). The syntax is -- SQLite can use indexes to avoid sorting when ORDER BY matches the index order.. It returns optimized sort order. A typical example: CREATE INDEX idx_emp_dept_name ON employees (department, last_name); -- This query avoids sorting — uses index order: SELECT * FROM employees ORDER BY department, last_name; -- Index: department (major), last_name (minor) -- Exactly matches ORDER BY, no filesort needed -- This query still sorts: SELECT * FROM employees ORDER BY last_name; -- Index starts with department, not last_name -- Partial match: only the leftmost prefix helps -- Use EXPLAIN QUERY PLAN… A close relative is AUTOINCREMENT (SQLite), which sQLite: unlike AUTO_INCREMENT in MySQL, only INTEGER PRIMARY KEY columns auto-increment. AUTOINCREMENT guarantees unique increasing IDs.