Patent ID: 7949655
Filing Date: 2011-05-24
Classification: G06F,Y10S

Abstract:
1. A method of performing a join in a database system comprising: receiving a join query containing at least one function selected from the group consisting of a selection predicate applied on a complex attribute, a projection applied on a complex attribute, and a user-defined data type method; determining, by at least one processor, a cost associated with applying the function on a first table and a cost associated with applying the function on a second table, wherein the join query specifies application of the function on the first table; and selecting, by the at least one processor, a join path based on relative costs of applying the function on the first and second tables, wherein selecting the join path comprises selecting the join path in which the function is applied on the second table rather than the first table based on a determination that the second table has a lower cardinality than the first table, the second table containing a join result of a join of the first table and another table.