This was my doubt "How Google Maps the World? What its database? What it do?". Found a nice article on this here. These are from that article:
..These images, which are shared by Google Maps, are actually a combination of aerial photos and satellite imagery--and a lot of postprocessing...
Looks like nothing database as such. Atleast for the current earth positions, it won't use any database. It uses the combination of aerial photos and the images from DigitalGlobe, the company that supplies Google's satellite photos, and do the image processing on them. May be, it need to use some spatial databases to store these and get them again whenever needed.
Below is the image from that article that explains most of the process