1. A computer-implemented method, comprising: identifying a set of access structures configured to support members of a set of database queries; identifying a set of basic configurations from the set of access structures; computing a net benefit associated with one or more members of the set of basic configurations; identifying a candidate configuration and an excluded configuration by selecting one or more members of the set of basic configurations as members of the candidate configuration based, at least in part, on a net benefit of a member of the set of basic configurations and adding non-selected members of the set of basic configurations to the excluded configuration; producing a reduced configuration by selectively moving one or more basic configurations from the candidate configuration to the excluded configuration based on an execution cost; and manipulating the reduced configuration by selectively moving one or more basic configurations from the excluded configuration to the reduced configuration based on a shared cost.