Database record compression system and method therefor including first and second dictionaries
AssigneeNEC Corporation
InventorMinoru Tamura
Life of this patent
Estimating the term…
Abstract
A database record compression system compresses data with frequency priority. The system has a formal dictionary for storing compressed strings and entry numbers corresponding to the compressed strings. A temporary dictionary compresses and stores strings of the plurality of strings input from an input file which are not stored in the formal dictionary. The system initializes all entries of the temporary dictionary when a number of registrations in the temporary dictionary reaches a predetermined number of initializations. In the system, an occurred string is registered in the formal dictionary when a frequency of occurrence of the string at the temporary dictionary reaches a predetermined number of times.
Claims19
A database record compression system for use with an input file for inputting a plurality of strings, comprising:
- a first dictionary for storing a plurality of compressed strings and entry numbers corresponding to the compressed strings;
- and
- a second dictionary for compressing and storing strings of the plurality of strings input from said input file which are not stored in said first dictionary,
- wherein said first dictionary comprises a formal dictionary and said second dictionary comprises a temporary dictionary, at least one entry of said temporary dictionary being initialized when a number of registrations in said temporary dictionary reaches a predetermined number of initializations.
A database record compression system for use with an input file for inputting a plurality of strings, comprising:
- a first dictionary for storing a plurality of compressed strings and entry numbers corresponding to the compressed strings;
- and
- a second dictionary for compressing and storing strings of the plurality of strings input from said input file which are not stored in said first dictionary,
- wherein said first dictionary comprises a formal dictionary and said second dictionary comprises a temporary dictionary, all entries of said temporary dictionary being initialized when a number of registrations in said temporary dictionary reaches a predetermined number of initializations.
A database record compression system which compresses record data, said record data including a plurality of strings, said system comprising:
- an input file for storing record data to be compressed;
- an output file for storing compressed record data;
- a first dictionary, coupled to said input file, for storing compressed strings and entry numbers corresponding to the compressed strings;
- a second dictionary for storing compressed strings which are not stored in said first dictionary;
- registration controlling means for scanning a record data from said input file, and registering the record data to one of said first dictionary and said second dictionary;
- and
- output means for outputting compressed record data to said output file.
A method of compressing a database record for use with a database record compression system having an input file for storing record data to be compressed, an output file for storing compressed record data, a first dictionary for storing a plurality of compressed strings and entry numbers corresponding to the compressed strings, and a second dictionary for storing compressed strings which are not stored in said first dictionary, comprising:
- a step of scanning record data having strings output from said input file;
- a step of registering the strings in said second dictionary;
- a step of initializing at least one entry of said second dictionary when a number of registrations in said second dictionary reaches a predetermined number of initializations;
- a step of registering an occurred string in said first dictionary when a frequency of occurrence at said second dictionary reaches a predetermined number of times;
- and
- a step of outputting compressed strings to said output file.
Dependencies are inferred from the claim text.