Column Order of Indexes
A case study testing how index column order affects query performance in SQLite.
Parameters
| Setting | Value |
|---|---|
| Database | SQLite 3.50.4 (64-bit) |
| OS | Arch Linux x86_64 |
| CPU | AMD Ryzen 5 6600H |
| Table Rows | 100,000 |
Experiment
- Create two databases with varying column index orders using Python
- Run query 30 times to avoid cold start bias
Results
The chart compares query execution times between different index column orders:
Conclusion
The order of columns in an index significantly impacts query performance depending on the query patterns. When the leading column of an index is used in WHERE clauses, the database can efficiently seek to the relevant portion of the index. However, if queries filter on columns that appear later in the index, the database may need to scan larger portions of the index.
💡 Key Takeaway: Place the most frequently filtered columns first in your index definition. Analyze your actual query patterns to determine the optimal column order for composite indexes.