WordPress Transients API

The Transients API is a built-in WordPress feature that allows developers to store cached data temporarily in the database with an optional expiration time. It’s used to improve performance by reducing expensive or repetitive operations such as API calls or complex queries.

Why Use Transients?

• Reduces database load and improves speed
• Ideal for storing temporary data like:
  • Remote API responses
  • Processed shortcodes
  • Query results
  • Third-party data

How It Works

A transient is stored with a name, a value, and an optional expiration time (in seconds).

Set a transient:

set_transient( 'my_cached_data', $data, 3600 ); // 1 hour

Get a transient:

$data = get_transient( 'my_cached_data' );

Delete a transient:

delete_transient( 'my_cached_data' );

If the data has expired or doesn’t exist, get_transient() returns false.

Where Is It Stored?

• By default, transients are stored in the WordPress options table (wp_options)
• If object caching (e.g., Redis or Memcached) is enabled, transients may be stored in-memory instead, improving performance

Real-World Use Case

Cache a remote API response to prevent repeated calls:

$response = get_transient( 'weather_data' );
if ( false === $response ) {
    $response = wp_remote_get( 'https://api.weather.com/data' );
    set_transient( 'weather_data', $response, 1800 );
}

Notes & Limitations

• Transients are not guaranteed to persist (especially without object caching)
• Ideal for non-critical, rebuildable data only
• Use a unique name prefix to avoid conflicts