In the recent years, our ability of collecting information rapidly increases and huge databases that change over time in a high frequency have been developed. On the other hand, the data mining techniques used for extracting essential information from raw data are rather complex, thus not synchronized to underlying data changes. There is a need of detecting whether synchronization operations should take place so as to rescue resources. Motivated from the above problem, we introduce the notion of similarity in data and pattern space and examine their relationship.