File management method using transposed file

• US 6,397,223 B1
• Filed: 10/26/1999
• Issued: 05/28/2002
• Est. Priority Date: 07/08/1999
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kori, Mitsunori
• Primary Examiner(s): Corrielus, Jean M.
• Application Number:
  US09/427,113
• Time in Patent Office: 945 Days
• Field of Search: 707/3,102,101,1,2,7,104,533,205 717/2,1 345/804,968 705/29 706/934
• US Class Current: 1/1
• CPC Class Codes: G06F 16/11 File system administration, e.g. details of archiving or snapshots file system backup G06F11/14
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99937 Sorting
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A file management system performs flexible and efficient file management with a transposed file. First, variable-length logical fields constituting the records in an original file are converted to variable-length internal fields with field-to-field correspondence being maintained and fields aligned with word boundaries. Next, the records consisting of internal fields are divided into multiple record groups which may comprise a variable number of records. For each record group, one or a plurality of internal fields of all records are then sorted into blocks and blocks are set in a row as a group. Groups thus generated from all records are assembled into a transposed file. When requested to retrieve field data from the original file, the file management system accesses the transposed file and reads only blocks comprising target field data.

Claims

1. A file management method for managing an original file that holds a plurality of records, each of which includes at least one variable-length field, comprising:

a field converting step for converting all fields that constitute said records stored into said original file to variable-length internal fields with field-to-field correspondence being maintained;

a record group generating step for generating record groups by dividing all records consisting of said internal fields into a plurality of groups;

a block generating step for generating blocks by sorting said internal fields of all records within a record group into blocks according to their relative positions so that records'"'"' fields in the corresponding position will be assembled into a same group; and

a transposed file generating step for generating a transposed file by setting in a row all blocks generated from each record group to reorganize a new group and then setting thus reorganized groups in a row;

wherein said transposed file is accessed in response to a request for data reading from said original file.

2. The file management method according to claim 1, wherein said field converting step makes all internal fields terminate, aligning with boundaries of physical units for access by adding space area to said internal fields.

3. The file management method according to claim 1, wherein said record group generating step generates record groups comprising a variable number of records and the storage location of data of a target field is determined by referring to the previously set number of records to constitute an individual record group when said transposed file is accessed.

4. The file management method according to claim 3, wherein said block generating step generates all groups of same size by adding space area to undersized blocks.

5. The file management method according to claim 3, wherein the size of an input-output buffer to temporarily store the field'"'"'s data read from said transposed file is set equivalent to the maximum block size determined when blocks are generated.

6. The file management method according to claim 3, wherein, each time field'"'"'s data is read from said transposed file, a minimum necessary size of input-output buffer for storing the read fields data is allocated.

7. The file management method according to claim 1, wherein said block generating step generates blocks comprising a plurality of fields in the corresponding positions in all records in a record group.

8. The file management method according to claim 7, wherein said block generating step assembles non-adjacent fields into one block.

9. The file management method according to claim 1, wherein if the size of a generated block is not equal to an integer multiple of minimum physical input-output units, said block generating step adds space area to the block in order to size the block to an integer multiple of the minimum input-output units.

10. The file management method according to claim 9, wherein said minimum physical input-output units are disk sector size.