The present invention provides a system, a method, and a program for checking index consistency online in a database that includes a main database storing a plurality of data segments and an index database storing a plurality of index segments. A system according to an aspect of the present invention includes a record creating unit for sequentially reading out the index segments from the index database and creating a pointer record that contains a pointer value and a key value and for sequentially reading out the data segments from the main database and create a segment record that contains a storage address and an indexed field value of an index target segment to be indexed among the read out segments, a scan point setting unit for setting scan points that indicate progress of creation of the pointer record and the segment record.