when i do a redim of an array, to raise the size, what happen with the data containing in the array, it loses?

i have an array based on the data from my DB, and i want to do a methode that verifys if there are new data, and if it have something, add to the array.
if some data is deleted i won´t lower the size, i just won´t use that object of the array anymore.

Thank you,
Guilherme Costa