How Can I Efficiently Select 10 Random Rows from a Large MySQL Table?

Optimizing Random Row Selection in Large MySQL Tables

Extracting 10 random rows from a substantial MySQL table (e.g., 600,000 rows) requires a strategy that prioritizes speed and efficiency. The naive approach of using ORDER BY RAND() is notoriously slow for large datasets. A more effective method is outlined below:

The following query provides a significantly faster solution:

<code class="language-sql">SELECT name
FROM random
WHERE id >= (SELECT FLOOR(RAND() * MAX(id)) FROM random)
ORDER BY id
LIMIT 10;</code>

This query works by first determining a random starting point within the id column's range using FLOOR(RAND() * MAX(id)). It then selects rows where the id is greater than or equal to this random starting point. Finally, it orders the results by id and limits the output to 10 rows. This avoids the full table scan inherent in ORDER BY RAND(), resulting in a substantial performance improvement. This approach ensures a relatively even distribution of random rows across the table.

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