For my custom post type,i had set the 'hierarchical' to true for my url to be like
http://example.com/custom/parent/child/.But there is this part in the WordPress codex.
Note: this parameter was planned for Pages. Be careful, when choosing it for your custom post type - if you are planning to have many entries (say - over 100), you will run into memory issue. With this parameter set to true WordPress will fetch all entries of that particular post type, together with all meta data, on each administration page load for your post type.
Does this means that its better not to set it to true,if i will have a lot of child pages? And if I don't use the hierarchical, how could I make the URL to be like the one above?