The method disclosed herein effectively caches timestamps in the memory of a query server. Each index file contains a base time and a set of documents with encoded timestamps. The base timestamp stored represents the index build time. The indexer encodes the timestamp of each document stored in the data directory. The difference of the absolute timestamp and the base timestamp is telescopically quantized into segmented time units. The compressed value of the segmented time units is stored in the index. During the querying process, the encoded timestamps for an individual document is recreated by applying a decoding process carried out in the query server. The reverse of the telescopic quantization is conducted to determine the absolute timestamp.