The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 02, 2001
Filed:
Mar. 26, 1999
Mark E. Melton, Round Rock, TX (US);
Robert M. Wehrmeister, Austin, TX (US);
Peter N. Lohman, Austin, TX (US);
Compaq Computer Corporation, Houston, TX (US);
Abstract
A database query compiler and compilation method has special facilities for compiling a query that includes an Offset sequence function, Offset(argument, index). During execution of the query, while the cursor for a table is pointing to a current row, the Offset function is used to access information from a previously accessed row. The argument of the Offset sequence function is a specified function of information associated with the previously accessed row of the table. The previously accessed row has a position that is index rows before the current row referenced by the cursor for the table. During compilation, the argument of the Offset sequence function is parsed to determine a set of auxiliary fields for each row of the table. Each auxiliary field of a row contains information that may be accessed during execution of the Offset sequence function while the cursor for that table is pointing to a subsequent row. The Offset sequence function is converted into a compiled set of instructions, including instructions for storing and reading the auxiliary fields to and from a buffer that is separate from the table. The buffer is preferably stored in volatile, main memory. As a result, the Offset sequence function is executed, and information from a previous row is accessed, without having to change the cursor position for the table.