1. A computer-executed method comprising: combining two or more path expressions of a first set of path expressions to form a fused path expression, wherein a particular query includes the path expressions of the first set; determining that the fused path expression is included in a second set of path expressions that are associated with a particular structured index; rewriting the particular query to include a subquery on the particular structured index; wherein the subquery is configured to retrieve, from the particular structured index, information referred to in the fused path expression; and wherein the method is performed by one or more computing devices.