IF i set rowNum=20 and  will add new record in the cycle, when the records will be > 20, there will be no entries are displayed. 

How can I find a record or not shown, and remove hidden?

For example:

global = $('#my_global').jqGrid({

.....

rowNum:20

...

});

I add a record in an endless cycle of one minute.

When the number of records become more than 20. 21 record is deleted from <table>.

But this record is not deleted from the object's date. (global[0].p.data) .

This is  memory leaks? How to deal with it? How to delete from global[0].p.data ?