A good rule of them with pie dough. Always have a little more than needed.
Having cracks in your pie dough is bound to happen. And sometimes you can get away with a little hole or crack here or there. (Like for a cream pie, it will be okay to have a small hole.) However, if the crust is for something that is liquid that will bake onto the crust, like pumpkin pie or quiche, then you will definitely need to find a way to patch up those holes and cracks. Otherwise, the liquid will leak out and you end up with pie filling on the outside of the crust.
In any case, it is a really easy fix. First, after lining the pie plate with the dough, save the leftover dough. (A paste of flour and a little water will do if you don't have enough dough.) After blind-baking* and you can use bits of the leftover dough to simply patch up these cracks and holes, but be gentle as the crust will break if you press down too hard. Then continue with the baking process, allowing the patches to bake into these holes and cracks. You can also do this, if one side of the crust has shrunken in the baking process. However, you will need dough for this part and not the flour/water paste.
Once you put your filling in and finish off the pie, no one will know about the holes and cracks.
(*Blind baking is a technique used when you need a pre-baked crust such as with custard pies or quiche. Lining the dough with foil and adding either beans or rice helps the crust keep it shape while baking. The beans or rice act as weights. You do this until the crust dries out. Then you remove the weights and return the crust to the oven for a few minutes to finish baking. )