Data managing method and apparatus, and recording medium

A data managing apparatus comprising:

• a data file for storing records each of which includes at least one item for a corresponding data unit, said data units subject to a predetermined sequence;
• an index file associated with said item;
• and
• record control means for controlling storing into said data file and said index file,
• wherein, responsive to a request for recording a data unit with respect to said item, said record control means produces a new record including said requested data unit and stores the new record into said data file, and further stores a change bit into said index file, said change bit representing whether said requested data unit in the new record differs from a data unit stored immediately before with respect to said item.

A data managing apparatus comprising:

• a data file storing records each of which includes at least one item having a corresponding data unit, said data units subject, to a predetermined sequence;
• an index file associated with said item and storing change bits representing whether the data units of said item have been changed in said predetermined sequence;
• and
• read control means for controlling reading from said data file and said index file,
• wherein, responsive to a retrieval request for a record whose data unit with respect to said item has been changed in contents, said read control means identifies the requested record based on the change bits stored in said index file.

A computer-readable recording medium storing a program which causes a computer to execute the steps of:

• forming a data file for storing records each of which includes at least one item for a corresponding data unit, said data units subject to a predetermined sequence;
• forming an index file associated with said item;
• producing, responsive to a request for recording a data unit with respect to said item, a new record including said requested data unit;
• storing the new record into said data file;
• and
• storing a change bit into said index file, said change bit representing whether said requested data unit in the new record differs from a data unit stored immediately before with respect to said item.

A computer-readable recording medium storing a program which causes a computer to execute the steps of:

• forming a data file storing records each of which includes at least one item having a corresponding data unit, said data units subject to a predetermined sequence;
• forming an index file associated with said item and storing change bits representing whether the data units of said item have been changed in said predetermined sequence;
• referring, responsive to a retrieval request for a record whose data unit with respect to said item has been changed in contents, to the change bits stored in said index file;
• and
• identifying the requested record based on said referred change bits.