Comparing Performance: IFNULL vs. COALESCE

When a database column can only have two candidate values, both IFNULL and COALESCE can be used to retrieve the non-null value. However, it's not immediately clear which function is faster.

Investigation

Despite the belief that IFNULL is superior, anecdotal evidence suggests that COALESCE may be equally or even more efficient.

Benchmarking Considerations

To determine which function is truly faster, it's essential to benchmark against specific usage scenarios. Data distribution and other environmental factors can impact the performance comparison.

Standardization

Moreover, it's worth noting that COALESCE has been part of the SQL standard since 1992, while IFNULL is not yet standardized. Standards help ensure consistency and interoperability across platforms.

Performance Equivalence

Based on a benchmark study conducted by Adam Machanic (Performance: ISNULL vs. COALESCE in SQL Server), the difference in performance between IFNULL and COALESCE is often negligible.

Conclusion

While both IFNULL and COALESCE can be used to handle null values, it's recommended to profile specific use cases to determine the optimal function for performance. Data distribution and the database environment play crucial roles in this evaluation. Standardization is also a factor to consider when making a decision.