How does database indexing work? Given that indexing is so important as your data set increases in size, can someone explain how does indexing works at a database agnostic level? For information on queries to index a field, check out How do I index a database column. Solution Why is it needed? When data is stored on disk based storage devices, it is stored as blocks of data. These blocks are accessed in their entirety, making them the atomic disk access operation. Disk blocks