Find the Largest Custom Field Values (WP-CLI)

if ( ! defined( 'WP_CLI' ) || ! WP_CLI ) {
    return;
}

WP_CLI::add_command( 'largest-meta', function ( $args, $assoc_args ) {
    global $wpdb;

    $tables = array(
        'post' => array( $wpdb->postmeta, 'post_id' ),
        'user' => array( $wpdb->usermeta, 'user_id' ),
        'term' => array( $wpdb->termmeta, 'term_id' ),
    );
    $which = $assoc_args['table'] ?? 'post';
    if ( ! isset( $tables[ $which ] ) ) {
        WP_CLI::error( 'Use --table=post, user or term.' );
    }
    list( $table, $owner ) = $tables[ $which ];
    $limit = max( 1, min( 200, (int) ( $assoc_args['limit'] ?? 15 ) ) );

    $rows = $wpdb->get_results( $wpdb->prepare(
        "SELECT $owner AS owner_id, meta_key, LENGTH(meta_value) AS bytes FROM $table ORDER BY bytes DESC LIMIT %d",
        $limit
    ), ARRAY_A );

    foreach ( $rows as &$row ) {
        $row['size'] = size_format( (int) $row['bytes'], 1 );
        unset( $row['bytes'] );
    }

    WP_CLI\Utils\format_items( $assoc_args['format'] ?? 'table', $rows, array( 'owner_id', 'meta_key', 'size' ) );
}, array(
    'shortdesc' => 'Lists the largest meta rows.',
    'synopsis'  => array(
        array( 'type' => 'assoc', 'name' => 'table', 'optional' => true, 'default' => 'post', 'options' => array( 'post', 'user', 'term' ) ),
        array( 'type' => 'assoc', 'name' => 'limit', 'optional' => true, 'default' => 15 ),
        array( 'type' => 'assoc', 'name' => 'format', 'optional' => true, 'default' => 'table', 'options' => array( 'table', 'csv', 'json' ) ),
    ),
) );