Keep track of all transients that could exist in an option so that you can delete them by prefix. Useful for deleting dynamically generated keys on sites with a persistent object cache. Note: be careful with garbage collection - only use this when there is a finite number of possible transient keys.

store-transient-list.php

<?php

/**
 * Set/update the value of a transient.
 *
 * Transients set using this function can later be deleted in bulk
 * based on their prefix using rth_delete_transients().
 *
 * @param  string $key        Transient key.
 * @param  mixed  $value      Transient value.
 * @param  int    $expiration Optional. Time until expiration in seconds.
 * @return bool               False if value was not set and true if value was set.
 */
function rth_set_transient( $key, $value, $expiration = 0 ) {

	$was_transient_set = set_transient( $key, $value, $expiration );

	if ( $was_transient_set ) {

		// Add key to the list of transient keys that could potentially exist.
		$transient_keys   = get_option( 'rth_transient_keys' );
		$transient_keys[] = $key;

		update_option( 'rth_transient_keys', array_unique( $transient_keys ) );
	}

	return $was_transient_set;
}

/**
 * Delete all transients with a key prefix.
 *
 * This function will only delete transients that were originally
 * set using rth_set_transient().
 *
 * @param  string   $prefix Prefix to search for.
 * @return int|bool         Count of total deleted or false on failure.
 */
function rth_delete_transients( $prefix ) {

	// Get transient keys that could potentially exist.
	$transient_keys = get_option( 'rth_transient_keys' );
	$total_deleted  = 0;

	if ( $transient_keys && is_array( $transient_keys ) ) {

		foreach ( $transient_keys as $index => $key ) {

			// If transient key starts with the prefix we're looking for,
			if ( substr( $key, 0, strlen( $prefix ) ) === $prefix ) {

				// Delete transient.
				$was_transient_deleted = delete_transient( $key );

				if ( $was_transient_deleted ) {

					// Remove transient from the keys that could potentially exist.
					unset( $transient_keys[ $index ] );

					$total_deleted++;
				}
			}
		}

		update_option( 'rth_transient_keys', array_values( $transient_keys ) );
	}

	return $total_deleted ? $total_deleted : false;
}