17. The computer readable storage medium of claim 16 , wherein performing the insignificance analysis of a particular URL parameter includes: grouping document identifiers in the cluster into multiple sets, each set corresponding to a unique document content with respect to other sets; and computing an insignificance index for the particular URL parameter in accordance with the number of document identifiers in each set in which the particular URL parameter has at least two different parameter values.
17. The computer readable storage medium of claim 16 , wherein performing the insignificance analysis of a particular URL parameter includes: grouping document identifiers in the cluster into multiple sets, each set corresponding to a unique document content with respect to other sets; and computing an insignificance index for the particular URL parameter in accordance with the number of document identifiers in each set in which the particular URL parameter has at least two different parameter values. 18. The computer readable storage medium of claim 17 , further including a numeric insignificance threshold, wherein the particular URL parameter is classified as content-relevant if its insignificance index is less than the insignificance threshold.