Browse Prior Art Database

Compressed Indexing Method

IP.com Disclosure Number: IPCOM000090337D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Chang, HK: AUTHOR

Abstract

An index key compression indexing block and entry examples are indicated. A compressed indexing method is a way of organizing an index of data records, the index including compressed keys and pointers to save storage space and save time for reading, writing and searching. Each entry in the compressed index contains three fields of data. The first field is a control field Cm and contains the front end compression byte Fm, which indicates the character position of the starting point of the compressed key. Such field also contains the position byte Pm which indicates the length of the compressed key. The second field is the compressed key field which contains the fully compressed key Km. The third field is the address field Am which contains an address pointing to the location of either a data record or another index record.

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Compressed Indexing Method

An index key compression indexing block and entry examples are indicated. A compressed indexing method is a way of organizing an index of data records, the index including compressed keys and pointers to save storage space and save time for reading, writing and searching. Each entry in the compressed index contains three fields of data. The first field is a control field Cm and contains the front end compression byte Fm, which indicates the character position of the starting point of the compressed key. Such field also contains the position byte Pm which indicates the length of the compressed key. The second field is the compressed key field which contains the fully compressed key Km. The third field is the address field Am which contains an address pointing to the location of either a data record or another index record.

In the example shown, the front portions of the actual keys are considered as relatively constant and the compressed keys refer to the nonconstant, lower- order positions of the actual keys. The compressed keys therefore refer to the first point in an actual key that differs from the immediately preceding actual key. The semicompressed key Xm is shown for understanding of the fully compressed key and the front end compression and position byte entries. The semicompressed key illustrates the complete actual key to the point of difference form the prior actual key. This point of difference is that comprising the fully co...