| 摘要 |
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. The system builds the value lookup table for tracking unique values in the cells. As additional unique values are inserted into the column of the user's table (i.e., maintained as the row-ordered cell array), the system assigns a small unique integer value to each unique user value. Instead of storing the original (wide) data value into the row-ordered array, the system instead stores the new (narrow) integer number into the row-ordered array. In response to a user request to retrieve a value for a given row number, the system fetches the appropriate chunk of the row-ordered array and retrieves the small integer value. This small integer value is then used to index into the value lookup table, for reconstituting the actual user data.
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