How to best delete orphan wp_postmeta

This snippet is good enough, use it with $wpdb. In this case I would use :

<?php
add_action( 'before_delete_post', 'my_func' );
function my_func( $postid ){

// We check if the global post type isn't ours and just return
global $post_type;   
if ( $post_type != 'my_custom_post_type' ) return;

// My custom stuff for deleting my custom post type here
}
?>

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