WordPress • Caching through Transients

In web development, performance is crucial. Slow-loading websites can lead to frustrated users, decreased engagement, and even lower search engine rankings. To optimize the speed and efficiency of WordPress websites, developers often turn to WordPress Transients.

What are WordPress Transients

WordPress Transients provide an easy-to-use and efficient way to cache data in WordPress. They are temporary storage options that allow developers to store and retrieve data, such as query results or API responses, for a specified period.

Where are WordPress Transients stored?

Within the WordPress database, the transient data is stored in the wp_options table. The wp_options table is a core component of WordPress that holds various site options and settings.

How to Use WordPress Transients

Using WordPress Transients is relatively straightforward. The process involves three primary steps: setting a transient, retrieving a transient, and checking if a transient exists.

Setting a Transient

To store data in a transient, use the set_transient() function. It requires three parameters: the transient name, the data to store, and the expiration time in seconds. Here’s an example:

set_transient('my_transient', $data, DAY_IN_SECONDS);

Retrieving a Transient

To retrieve the data from a transient, use the get_transient() function. It takes the transient name as the parameter and returns the stored data if it exists. If the transient has expired or doesn’t exist, it returns false. Here’s an example:

$data = get_transient('my_transient');
if (false === $data) {
    // Transient doesn't exist or has expired
    // Fetch and set the data again
}

Deleting a Transient

To delete a transient in WordPress, you can use the delete_transient() function. Here’s an example:

delete_transient('my_transient');

Practical Example

The following code checks if a transient named ‘cooking_posts_query’ exists or has expired, and if so, fetches cooking posts data using WP_Query and sets it in the transient with a one-day expiration time.

$cooking_posts_query = get_transient('cooking_posts_query');
if ( $cooking_posts_query === false ) {
	// Transient doesn't exist or has expired
  // Fetch and set the data again
	$cooking_posts_query = new WP_Query( 
		array( 'tag' => 'cooking' ) 
	);
	set_transient('cooking_posts_query', $cooking_posts_query, DAY_IN_SECONDS);
}

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