13. The one or more non-transitory computer-readable storage media of claim 12 , wherein the first outer join is a full outer join of the first database object and the second database object, and wherein the second predicate is for a left outer join of the first database object and the second database object.
12. One or more non-transitory computer-readable storage media storing instructions which, when executed by one or more computing devices, cause: transforming a first query to a transformed query; wherein the first query includes: a first outer join of a first database object and a second database object, and a first join predicate that specifies a first condition of the first database object for the first outer join, wherein the first join predicate does not reference the second database object; wherein the transformed query does not include the first join predicate but does include: a second predicate that specifies a second condition of the first database object, wherein the second predicate references the second database object; wherein the transformed query is semantically equivalent to the first query; causing execution of the transformed query instead of the first query.