International Business Machines Corporation

Partha Pratim Bhattacharya

Yun Yu Wang

Mir Hamid Pirahesh

Mahmoud Naghshineh

Jen-Yao Chung

Arvind Krishna

Jeane S Chen

Patricia G Selinger

Roger Y Cheung

Murray C Baker

Peter E Reissner

Marisa S Viveros

Lawrence Peter Zaino

A method of performing a parallel join operation on a pair of relations R1 and R2 in a system containing P processors organized into Q clusters of P/Q processors each. The system contains disk storage for each cluster, shared by the processors of that cluster, together with a shared intermediate memory (SIM) accessible by all processors. The relations R1 and R2 to be joined are first sorted on the join column. The underlying domain of the join column is then partitioned into P ranges of equal size. Each range is further divided into M subranges of progressively decreasing size to create MP tasks T.sub.m,p, the subranges of a given range being so sized relative to one another that the estimated completion time for task T.sub.m,p is a predetermined fraction that of task T.sub.m-1,p. Tasks T.sub.m,p with larger time estimates are assigned (and the corresponding tuples shipped) to the cluster to which processor p belongs, while tasks with smaller time estimates are assigned to the SIM, which is regarded as a universal cluster (cluster 0). The actual task-to-processor assignments are determined dynamically during the join phase in accordance with the dynamic longest processing time first (DLPT) algorithm. Each processor within a cluster picks its next task at any given decision point to be the one with the largest time estimate which is owned by that cluster or by cluster 0.

Method of performing a parallel relational database query in a

A method of routing packets through a fixed source routing communications network from and to mobile units. With this invention an initial access point is determined when a communications session is established to or from a mobile unit through the network. Location information is updated each time the mobile unit moves out of the range of one access point and into the range of another access point of the network. When packets for the session are to be transmitted to the mobile unit from the wired network, the packets are forwarded from the initial access point to a current access point, which by definition is in the range of the mobile unit. When packets for the session are to be transmitted from the mobile unit and to the wired network, the access point intercepts these packets and routes them to their destination and/or initiates route discovery to those destinations. When packets are to be transmitted between mobiles at different access points. The packets are sent between the current access points and not through the home access points.

Mobility enabling access point architecture for wireless attachment to

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Briarcliff Manor, NY, United States of America

Partha Pratim Bhattacharya