1. A computer-implemented method for accessing user-defined fields of a table, the method comprising: receiving a database operation that involves accessing a record in the user-defined fields of the table, wherein the record is mapped to a record stored in a custom field of a custom-field table associated with the table, wherein the record in the custom field is of the same data type and has the same index value as the record in the user-defined field, and wherein a value for the record in the user-defined field is stored in the custom field at a position based on an integer quotient, which is determined by dividing the index value by the number of customer fields in each row of the custom-field table; mapping, by computer, the user-defined field to the custom field of the custom-field table by: identifying the index value associated with the user-defined field; identifying the position associated with the user-defined field; and identifying the record corresponding to the user-defined field among records in the custom field of the custom-field table based on the index value and the position; and allowing the database operation to access the identified record in the custom field of the custom-field table.