A Genetic Algorithm for Vertical Fragmentation and Access Path Selection

Vertical fragmentation and access path selection are interdependent techniques in physical database design used to enhance performance in database systems. While vertical fragmentation in relational databases deals with assignment of attributes to physical files, access path selection deals with searching efficiently the physical location of data records. Vertical fragmentation is a combinatorial optimization problem that is NP-hard in most cases. We propose a genetic algorithm approach for the vertical fragmentation problem while addressing access path selection. The effectiveness and efficiency of the genetic algorithm are illustrated through several database design problems, ranging from 10 attributes/5 transactions to 30 attributes/18 transactions. In most cases, our design solutions match the global optimum solutions obtained from an exhaustive enumeration. Compared to unpartitioned databases, our design solution results in substantial savings (up to 80%) in the number of disk accesses.