Disclosed is a method performed by a database management system (DBMS) according to an exemplary embodiment of the present disclosure. The method may create a database index structure for pointing a data storage location based on monitoring result information depending on a monitoring algorithm in the database management system. The database index structure may at least partially include a sub index structure of a first level and a sub index structure of a second level which is lower than the first level, the second level sub index structure may include a plurality of columns, a first column among the plurality of columns of the second level sub index structure may include key values, a second column among the plurality of columns of the second level sub index structure may include ROWID values corresponding to rows of a data block, and a third column among the plurality of columns of the second level sub index structure may include optimized index values set based on the monitoring result information.