Define and differentiate between ordered indexing and hashing.

Ans: Ordered indexing: To gain fast random access to records in a file, we can make of an index structure. Every index structure is related with a specific search key. An ordered index stores the values of the search keys in sorted order and relates with each search key records which contain it. The records in the indexed file may themselves be stored in some sorted order. A file may have various indices on different search keys.                     

Hashing: It as well provides a way of constructing indices. In hashing, the address of the disk lock consisting of a desired record directly is computed by a function on the search-key value of the record.

Differentiate among the ordered indexing and hashing: Ordered indexing is stored in sorted order while in Hashing search keys are distributed consistently across "buckets" using 'hash function'.