MySQL Pagination: Efficiently Retrieving Results and Total Count

When implementing pagination in MySQL, it's common practice to perform two separate queries: one to get the total number of results and another to limit the fetched records. This approach, known as double-querying, can be inefficient for large datasets.

However, the question arises whether it's possible to retrieve both the total result count and limit the results in a single query. While there is no direct way to achieve this, two alternative methods are available:

SQL_CALC_FOUND_ROWS and FOUND_ROWS()

Instead of double-querying, you can utilize the SQL_CALC_FOUND_ROWS and FOUND_ROWS() functions to achieve a similar result. The query with SQL_CALC_FOUND_ROWS precedes the limiting query, and the FOUND_ROWS() call fetches the total count.

Example:

SELECT SQL_CALC_FOUND_ROWS * FROM `table` WHERE `some_condition`;
SELECT FOUND_ROWS();

Note: This method has a potential drawback. MySQL has a bug that impacts ORDER BY queries when using this technique, making it slower on large tables.

Caching the Count

An alternative solution involves caching the total count for a specific duration. This approach eliminates the need for a separate query to fetch the count while preserving efficiency.

Example:

Retrieve the count and cache it for 10 minutes:

SET @count = (SELECT COUNT(*) FROM `table` WHERE `some_condition`);

In subsequent queries, use the cached count:

SELECT * FROM `table` WHERE `some_condition` LIMIT 0, 10;

Caching the count significantly improves performance, especially for frequently visited pages. While it's not a single-query solution, it achieves the same result while being more efficient than double-querying.