公开(公告)号：CA2168287A1

公开(公告)日：1996-10-01

申请号：CA2168287

申请日：1996-01-29

Applicant: IBM

Inventor： LOHMAN GUY M ,  SCHIEFER BERNHARD ,  URATA MONICA S

IPC: G06F17/30

公开(公告)号：CA2146171A1

公开(公告)日：1996-10-04

申请号：CA2146171

申请日：1995-04-03

Applicant: IBM CANADA

Inventor： SCHIEFER BERNHARD ,  STRAIN LORI G ,  YAN WEIPENG P

IPC: G06F16/245 ,  G06F16/2453 ,  G06F17/30

Abstract: The present invention provides a method for estimating cardinalities for query processing in a relational database management system. The present method is suitable for use with a query optimizer for estimating cardinalities for sets of columns or keys resulting from a grouping operation or a duplicate removal operation.

公开(公告)号：CA2124094A1

公开(公告)日：1995-11-21

申请号：CA2124094

申请日：1994-05-20

Applicant: IBM CANADA

Inventor： SCHIEFER BERNHARD ,  SWAMI ARUN N

IPC: G06F17/30 ,  G06F15/401

Abstract: Described herein is a system and method for operating a data processing system having a processing unit and physical storage in which data is stored. The storage is connected to the processing unit for transferring pages of data to the processing unit. The storage contains at least one database table stored on a plurality of pages. Each data base table has a plurality of rows of data, and one or more indexes composed of a sequence of entries which reference the rows. The processing unit has a memory associated with it. A portion of the memory comprises a buffer pool for caching data pages from the table. The method operates by scanning one or more selected indexes in determining the relationship of the number of data transfers required to traverse all or a portion of each selected index for a selected range of buffer pool sizes. Then, a description of this relationship is stored.\!