A computer-implemented method, system and computer program product for minimizing hash collisions of composite keys. Each component (“key component”) of the composite key is converted into a linear index that uniquely represents that key component. Such a one-to-one mapping reduces the length (i.e., range of values the key component represents) of each component without introducing any collisions thereby effectively resulting in the lossless compression of the individual key components. Such a linear index for each converted key component is stored in a separate lookup memory. A reduced composite key is then created by joining together the linear indices that represent the components of the composite key thereby reducing the total length or domain (i.e., range of values the composite key represents) of the original composite key in a lossless manner. In this manner, by reducing the total length of the composite key, hash collisions of composite keys are minimized.