Mysql query with Left Join is too very slow

Question

Query:

   select `r`.`id` as `id` 
     from `tbl_rls` as `r` 
left join `tblc_comment_manager` as `cm` on `cm`.`rlsc_id` != `r`.`id`

Both tabl

Answer 1

MySQL's EXPLAIN might help you finding out what is going on.