I/O Efficient Dynamic Data Structures for Longest Prefix Queries

We present an efficient data structure for finding the longest prefix of a query string q in a dynamic database of strings. When the database strings are prefixes of IP‐addresses then this is the IP‐lookup problem. Our data structure is I/O efficient. It supports a query with a string q using $O({\log }_B(n)+\frac{\mid q\mid }{B})$ I/O operations, where B is the size of a disk block. It also supports an insertion and a deletion of a string q with the same number of I/Os. The data structure requires O(n/B) blocks, and the running time for each operation is O(Blog B (n)+|q|).