Is there any other (faster) technique to retrieve pairwise images in a huge dataset?

edit

The basic thing is to be smart about your storage, and choose your descriptor wisely. Structures like the k-d tree show methods for searching high-dimensional data quickly. Your choice of descriptor matters as well, the better you can compress the image into a descriptor the better, because smaller descriptors are faster to check. Of course, the speed of calculating the descriptor matters too.

This is a very active area of research, typically with the keywords "image retrieval". Search Google Scholar with those keywords and begin reading. You can limit it to newer papers to get the best, but be sure to look at the citations to find good papers from the past that explain the basics.