There is provided a query execution method in a DB system in which a plurality of CSDs are used as a storage. According to an embodiment, a query execution method includes: generating snippets for offloading a part of query computations for a query received from a client to CSDs; scheduling the generated snippets for the CSDs; collecting results of offloading; and merging the collected results of offloading. Accordingly, by dividing query computations, offloading, and processing in parallel, while processing query computations that are inappropriate for offloading by a DBMS, a query request from a client can be executed effectively and rapidly.