10. A non-transitory computer-readable storage medium encoded with computer-executable instructions to select a preferred data set, which in response to execution by a computing device, cause the computing device to perform or control performance of operations that comprise: process a first relation to retain a set of tuples in the first relation, wherein the set of tuples includes at least one of a fully dominated tuple, a locally dominated tuple, and a non-locally dominated tuple in the first relation, wherein the retained set of tuples comprises a first set of tuples that corresponds to the fully dominated tuple in the first relation, and wherein the first relation includes a first join attribute and a plurality of first existence probability attributes; process a second relation to retain another set of tuples in the second relation, wherein the another set of tuples includes at least one of a fully dominated tuple, a locally dominated tuple, and a non-locally dominated tuple in the second relation, wherein the retained another set of tuples comprises a second set of tuples that corresponds to the locally dominated tuple in the second relation, wherein the second relation includes a second join attribute compatible with the first join attribute and a plurality of second existence probability attributes, and wherein the first join attribute is compatible with the second joined attribute based at least on a logical relationship between the first join attribute and the second join attribute; generate a joined relation based on the first relation and the second relation, wherein the joined relation comprises a first joined tuple which is joined based on a tuple from the first set of tuples and a tuple from the second set of tuples, and wherein the joined relation further comprises a skyline probability attribute based, at least in part, on a product of a value of the plurality of first existence probability attributes and a value of plurality of the second existence probability attributes; and select the preferred data set from the joined relation based on a comparison of a first value of the skyline probability attribute and a skyline probability threshold; compare a first joined tuple with one or more target tuples in the joined relation to determine whether the first joined tuple is fully dominated by the one or more target tuples, wherein the one or more target tuples comprise tuples formed by joining the tuple from the second set of tuples with the set of tuples in the first relation; and select the first joined tuple based on a determination that the first joined tuple is not dominated by the one or more target tuples, wherein the comparison of the first joined tuple with the one or more target tuples in the joined relation eliminates unnecessary comparisons with tuples formed by joining one or more tuples from the set of tuples in the first relation with one or more tuples from the another set of tuples in the second relation.
10. A non-transitory computer-readable storage medium encoded with computer-executable instructions to select a preferred data set, which in response to execution by a computing device, cause the computing device to perform or control performance of operations that comprise: process a first relation to retain a set of tuples in the first relation, wherein the set of tuples includes at least one of a fully dominated tuple, a locally dominated tuple, and a non-locally dominated tuple in the first relation, wherein the retained set of tuples comprises a first set of tuples that corresponds to the fully dominated tuple in the first relation, and wherein the first relation includes a first join attribute and a plurality of first existence probability attributes; process a second relation to retain another set of tuples in the second relation, wherein the another set of tuples includes at least one of a fully dominated tuple, a locally dominated tuple, and a non-locally dominated tuple in the second relation, wherein the retained another set of tuples comprises a second set of tuples that corresponds to the locally dominated tuple in the second relation, wherein the second relation includes a second join attribute compatible with the first join attribute and a plurality of second existence probability attributes, and wherein the first join attribute is compatible with the second joined attribute based at least on a logical relationship between the first join attribute and the second join attribute; generate a joined relation based on the first relation and the second relation, wherein the joined relation comprises a first joined tuple which is joined based on a tuple from the first set of tuples and a tuple from the second set of tuples, and wherein the joined relation further comprises a skyline probability attribute based, at least in part, on a product of a value of the plurality of first existence probability attributes and a value of plurality of the second existence probability attributes; and select the preferred data set from the joined relation based on a comparison of a first value of the skyline probability attribute and a skyline probability threshold; compare a first joined tuple with one or more target tuples in the joined relation to determine whether the first joined tuple is fully dominated by the one or more target tuples, wherein the one or more target tuples comprise tuples formed by joining the tuple from the second set of tuples with the set of tuples in the first relation; and select the first joined tuple based on a determination that the first joined tuple is not dominated by the one or more target tuples, wherein the comparison of the first joined tuple with the one or more target tuples in the joined relation eliminates unnecessary comparisons with tuples formed by joining one or more tuples from the set of tuples in the first relation with one or more tuples from the another set of tuples in the second relation. 11. The computer-readable storage medium of claim 10 , wherein the operations further comprise: process the first relation to retain a third set of tuples in the first relation which are non-fully dominated tuples, wherein the non-fully dominated tuples of the third set include at least one of the locally dominated tuple and the non-locally dominated tuple of the first relation.