公开(公告)号：CA1290456C

公开(公告)日：1991-10-08

申请号：CA589118

申请日：1989-01-25

Applicant: IBM

Inventor： CHANG PHILIP Y ,  COYLE DANIEL J JR ,  MALKEMUS TIMOTHY R ,  RODRIGUEZ REBECCA A ,  WELTI PHILIP J

IPC: G06F12/00 ,  G06F7/24 ,  G06F17/30 ,  G06F15/40

Abstract: AT9-88-011 In a relational database system, a method is utilized that increases the performance of the sort operation. An optimizer routine in the relational database manager analyzes a user's complete query to determine whether the final sorted results can be used directly by the user as sorting occurs. If the sort results can be used, the sort results are sent to Relational Data Services in the relational database manager for output to the user. Depending upon the determination made by the optimizer routine, one of two output modes for the final sorted sequence string of data are selected by the relational database manager. In disk output mode, the last pass of the final sorted sequence string is written to disk. In fast direct output mode, the records of data are sent to the user as the final sorted sequence string is being merged during the last pass. The system and method of this invention reduces the total sort time by eliminating the overhead of writing to disk during the fast direct output mode. Also, the response time, or availability for each record is reduced since each record is retrieved or sent to the Relational Data Services immediately after it has been sorted into the final sort order instead of completing the entire sort first, and then writing to disk.