SQL Row Count Optimization: `SELECT SQL_CALC_FOUND_ROWS` vs. `SELECT COUNT(*)` – Which is Faster?

SQL Performance Optimization: Comparing "SELECT SQL_CALC_FOUND_ROWS..." and "SELECT COUNT(*)" for Row Counts

In SQL database optimization, determining the total number of records in a table is crucial for pagination and other operations. Two common methods for this task are "SELECT SQL_CALC_FOUND_ROWS..." and "SELECT COUNT(*)".

Method 1: "SELECT SQL_CALC_FOUND_ROWS..."

This method uses the "SQL_CALC_FOUND_ROWS" option in the initial SELECT query to prepare the server for returning the total row count. After the initial query, you can retrieve the total count using "SELECT FOUND_ROWS()".

Method 2: "SELECT COUNT(*)"

Alternatively, you can run a separate query using "SELECT COUNT(*)" to directly count the total rows in the table.

Performance Comparison

The optimal method for determining row counts depends on specific factors. According to the MySQL Performance Blog, the efficiency of "SQL_CALC_FOUND_ROWS" varies based on indexes and other configuration settings.

Observations from Experts

Peter Zaitsev, the author of the MySQL Performance Blog, suggests that "SQL_CALC_FOUND_ROWS" is generally slower than running two separate queries for most scenarios. Many commentators on the blog post also indicate that "SQL_CALC_FOUND_ROWS" can be significantly slower, even by a factor of 10.

Conclusion

While "SELECT SQL_CALC_FOUND_ROWS..." can be beneficial in certain situations, it's generally recommended to use "SELECT COUNT(*)" for performance-critical applications where minimizing execution time is essential. However, it's always advisable to test both methods with your specific data and configuration to determine the optimal approach for your use case.

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