CareerCup

spatial index?

Assuming that buckets are contiguous in space and a rectangle represented by bucket is aligned with X and Y axis.

Question boils down to finding match in a row-wise and column-wise sorted matrix.

For database vs memcached, I think it will depend on the usage. Say we are using this for an gps application. In that case memcached must be used.

Based on sign one can identify which plane that coordinate belongs to.

Build a 2D interval search tree using the list of lat and long.