How to Efficiently Select Random Rows from Large MySQL Tables?

Efficiently select random rows from large MySQL tables

Selecting a random subset of rows is a common but challenging task when working with large data sets. For a table with 600,000 rows, finding a fast and efficient way to select 10 random rows is crucial.

Solution

For best performance in this situation, consider the following:

This solution utilizes the RAND() function and the CEIL() function to generate random IDs within an acceptable range. The JOIN operation then retrieves the corresponding row based on the randomly generated ID. By using ORDER BY r1.id ASC and LIMIT 1, the query ensures that the correct row is selected.

It is important to note that this method assumes a uniform distribution of IDs and allows for gaps in the ID list. For more advanced scenarios, such as non-uniform distribution and missing IDs, please refer to the article provided by Jan Kneschke for additional examples and strategies.

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