Delete All Post Meta Except Thumbnail In WordPress Pages and Posts

clean-post-meta.txt

//Originally found here: https://www.kvcodes.com/2015/12/delete-all-post-meta-except-thumbnail-in-wordpress-posts/
//Copy from line 3 to the end and paste into your theme's function file.
function kv_delete_all_meta_except_featuredimg(){
	$args = array( 'posts_per_page' => -1, 'post_status' => 'any',  'post_type' => array('attachment', 'page','post')); 
	$articles= get_posts( $args );

	foreach($articles as $article){
		if($article->post_type == 'attachment'){
			$myvals = get_post_meta($article->ID);
			foreach($myvals as $key=>$val)	{						
				if($key == '_wp_attached_file' || $key == '_wp_attachment_metadata'){} else {
				    	delete_post_meta($article->ID, $key);				   
				}
			}
		}else {
			$myvals = get_post_meta($article->ID);
			foreach($myvals as $key=>$val)	{
			      if($key != '_thumbnail_id' ){
				    delete_post_meta($article->ID, $key);
		              }
			}
		}
	}
}
add_action('init','kv_delete_all_meta_except_featuredimg');