1. A method for sampling analysis, comprising: classifying, using a computer processor, a plurality of query keywords into a plurality of query keyword subsets according to page view (PV) values associated with the plurality of query keywords, the plurality of query keywords being submitted by a plurality of users, wherein classifying the plurality of query keywords comprises: ordering the PV values associated with the plurality of query keywords; and grouping, based on the ordered plurality of PV values, query keywords with the same PV value to form respective ones of the plurality of query keyword subsets, such that query keywords with the same PV value are found within the same query keyword subset; determining a plurality of sample rates of corresponding ones of the plurality of query keyword subsets, wherein a given sample rate of the plurality of sample rates is determined by at least: calculating a sum of page view values (SPV) in a corresponding query keyword subset; calculating a sample probability by dividing the SPV in the corresponding query keyword subset by a total number of all user query keywords submitted by the plurality of users within a predetermined period of time; and multiplying the sample probability by a predetermined sample size; sampling query data in the plurality of query keyword subsets according to the respective ones of the plurality of sample rates, wherein the sampling includes sampling all of the plurality of query keyword subsets; and outputting the sampled query data.