1. A computer implemented method for constructing a referentially-complete target subset database from a source database, the method comprising: estimating an expected size of the target subset database based at least in part on application of a set of database subset rules on the source database, wherein the set of database subset rules comprises one or more database subset rules specifying one or more portions of the source database to be included in the target subset database; determining if the expected size of the target subset database meets a target subset database size goal, wherein if the goal is not met: modifying the set of database subset rules based at least in part on the expected size of the target subset database, such that application of the modified set of database subset rules on the source database results in the target subset database having a second expected size that is different from the expected size; creating a subsetting execution plan by applying the modified set of database subset rules to the source database; and generating, by a computer, the referentially-complete target subset database by applying the selected subset execution model to the subsetting execution plan.