Minimum leaf spanning tree

An efficient set of indexes to cover a plurality of anticipated query types is determined by building a directed acyclic graph whose nodes correspond to anticipated query types. A minimum leaf spanning tree for the equivalent graph is determined by repeatedly finding an augmenting path for a current spanning tree and producing a reduced leaf spanning tree based on the current spanning tree and the augmenting path until an augmenting path can no longer be found. The leaves of the minimum leaf spanning tree indicate which indexes should be built.