Inconsistent behavior of select all rows checkbox with pagination

[anatoly314]

Will try my best to describe my issue, hope I'll success with it. For example I have in total 100 rows, and pagination (with lazy loading) set up to show only 20 rows each time. It means that each time when I move backward, forward I issue request to server to load next chunk of data.

Sometimes I need to perform a group action on all rows. But I can't distinguish between a scenario when user selected all rows checkbox and user selected manually an each row on a page. In a both cases ngModel which represents selected rows, populated with equal amount of rows.