1. A computer-implemented method for performing predicate evaluation on a compressed variable length character string comprising: determining, by a processor, upper and lower boundaries of a false positive range for a predicate, the false positive range for the predicate being a range in which a result of the predicate evaluation leads to a false positive error; compression-encoding, by the processor, the upper and lower boundaries of the false positive range; performing, by the processor, a first comparison for comparing the compressed variable length character string with the compression-encoded upper and lower boundaries of the false positive range; determining, by the processor, a result of the predicate evaluation based on at least a result of the first comparison; determining, by the processor, upper and lower boundaries of a false negative range for the predicate, the false negative range for the predicate being a range in which a result of the predicate evaluation leads to a false negative error; compression-encoding, by the processor, the upper and lower boundaries of the false negative range; and performing, by the processor, a second comparison for comparing the compressed variable length character string with the compression-encoded upper and lower boundaries of the false negative range, wherein determining the result of the predicate evaluation based on at least the result of the first comparison comprises determining the result of the predicate evaluation based on the result of the first comparison and a result of the second comparison, said determining the result of the predicate evaluation based on the result of the first comparison and the result of the second comparison further comprises: determining, by the processor, a first evaluation result to be true in response that the compressed variable length character string is within a range defined by the compression-encoded upper and lower boundaries of the false positive range, and otherwise determining the first evaluation result to be false; determining, by the processor, a second evaluation result to be true in response that the compressed variable length character string is within a range defined by the compression-encoded upper and lower boundaries of the false negative range, and otherwise determining the second evaluation result to be false; determining, by the processor, the result of the predicate evaluation to be the first evaluation result in response that the first evaluation result is consistent with the second evaluation result; and decompressing, in response that the first evaluation result is inconsistent with the second evaluation result, the compressed variable length character string and performing the predicate evaluation on the decompressed variable length character string to obtain the result of the predicate evaluation.