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Abstract

A Client/Server Database System with improved methods for performing database queries, particularly DSS-type queries, is described. The system includes one or more Clients (e.g., Terminals or PCs) connected via a Network to a Server. In general operation, Clients store data in and retrieve data from one or more database tables resident on the Server by submitting SQL commands, some of which specify 'queries'--criteria for selecting particular records of a table. The system implements methods for storing data vertically (i.e., by column), instead of horizontally (i.e., by row) as is traditionally done. Each column comprises a plurality of 'cells' (i.e., column value for a record), which are arranged on a data page in a contiguous fashion. By storing data in a column-wise basis, the system can process a DSS query by bringing in only those columns of data which are of interest. Instead of retrieving row-based data pages consisting of information which is largely not of interest to a query, column-based pages can be retrieved consisting of information which is mostly, if not completely, of interest to the query. The retrieval itself can be done using more-efficient large block I/O transfers. The system includes data compression which is provided at the level of Cache or Buffer Managers, thus providing on-the-fly data compression in a manner which is transparent to each object. Since vertical storage of data leads to high repetition on a given data page, the system provides improved compression/decompression.

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First Claim