estimates the number of block accesses required to find all index records having a particular search key . the method uses the table 's metadata to estimate the size of the index file and the number of index records per block . it then passes this information to the traversalcost method of the appropriate index type , which provides the estimate . concode_field_sep String fldname concode_elem_sep Transaction tx concode_elem_sep TableInfo ti concode_elem_sep StatInfo si concode_elem_sep String idxname concode_field_sep Schema schema concode_elem_sep int distinctValues concode_elem_sep int recordsOutput concode_elem_sep Index open