Patent ID: 6363387
Filing Date: 2002-03-26
Classification: G06F,Y10S

Abstract:
In a database system having a database storing a database table comprising a plurality of data rows, said rows storing information organized into particular database fields, an improved method for granting access during a table scan to particular rows that meet a specified scan criterion, said table scan occurring during execution of multiple concurrent transactions, the method comprising:providing each row of the database table with delete and update status flags for indicating which rows may be skipped during the table scan, wherein: (i) the update status flag for a row is set when a transaction updates the row and is cleared when the transaction commits, (ii) the delete status flag for a row is set when a transaction delete a a row and is cleared when the transaction rolls back, and (iii) both the update and delete status flags for a row are restored to their respective prior states when a transaction rolls back that had flagged the row as updated; based on said status flags, determining those rows of the database table that may be skipped during the table scan; and granting access to particular rows of the database table that meet said specified scan criterion and have not been determined to be rows that may be skipped.