Index-only tables with nested group keys
US5852822A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1996 |
| Grant date | Dec 22, 1998 |
| Priority date | — |
| Expiry date | Dec 9, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99952
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for building, maintaining, and using a multi-level index is provided. The multi-level index is accessed using a key. The key is divided into multiple portions referred to as sub-keys. The first level of the multi-level index is built on a first-level sub-key. Each index entry at the first-level is for a particular first-level sub-key value, and either includes sub-entries associated with second-level sub-key values or a reference to a second-level data retrieval structure. All second-level data retrieval structures are built on the portion of the key that has been designated as the second-level sub-key. As the vocabulary of the first-level sub-key becomes exhausted, fewer maintenance operations will have to be performed to maintain the first-level data retrieval structure. This decreases the overhead and increases the concurrency in a database system that uses the multiple-level index. The multi-level index structure is especially suited for queries that retrieve all values for a given first-level sub-key. The structure also has reduced storage costs compared to a single-level index structure, since first-level sub-key values are stored only once for each nes…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.