Function and usage of delete_expired_transients() in wordpress


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    The delete_expired_transients() function in WordPress is designed to remove all expired transients from your WordPress database. Transients are a type of cache that WordPress uses to store temporary data with an expiration time. Here's a breakdown of this function:


    delete_expired_transients( bool $force_db = false )


    • Deletes all expired transients: This function is used to clean up the WordPress database by removing transient records that have expired.


    • Limited Use with External Object Cache: The function won't have any effect if an external object cache is being used. This is because external object caches handle transient expiration differently.
    • Multi-table Delete Syntax: The function uses a multi-table delete syntax. This means it deletes the transient record from one table (let's call it table a), and simultaneously deletes the corresponding transient_timeout record from another table (table b). The transient_timeout record is what WordPress uses to track when a transient should expire.


    • $force_db (bool, optional): This parameter controls whether the cleanup process should run against the database even when an external object cache is in use.
      • Default Value: false
      • When set to true, it forces the cleanup to happen in the database regardless of whether an external cache is being used.

    Sample Usage:

    Here's a basic example of how you might use delete_expired_transients() in a WordPress plugin or theme:

    // Check if you want to force the cleanup in the database
    $force_cleanup = true;
    // Run the function to delete all expired transients
    delete_expired_transients( $force_cleanup );

    In this example, $force_cleanup is set to true, which means the function will force a cleanup in the database, even if you're using an external object cache.

    Good to Know:

    • Usage Frequency: This function is typically not something you would call frequently in your code. It's more of a maintenance function.
    • Performance Considerations: Be cautious about running this in high-traffic environments, especially with $force_db set to true, as it could impact database performance.

    Remember to test any code using this function in a staging environment before deploying it to a live site to ensure it doesn't negatively affect your site's performance or user experience.

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