How to get all records of a view with paging?
If you don't mind installing another module, try Views Bulk Operations.  Views Bulk Operations (often abbreviated VBO) allows you to add "select all on page/select all everywhere" checkboxes and also offers additional functions such as using batch API to process operations when there are too many to do at once (if you had 20,000 records instead of 20).

Node One has a tutorial on VBO.