Abstract: Techniques for simulating a multiprocessor system. Aspects of the present invention are based on such an observation that most memory accesses from different simulated processors do not conflict, and therefore the conservative policy for performing synchronization of all the memory accesses can waste a large amount of processing time. By identifying possibly conflicting memory accesses and only performing synchronization of these memory accesses, the synchronization cost can be reduced considerably. Since the function simulator is able to operate faster and to perform the same memory accesses, the possibly conflicting memory accesses can be identified by first executing the function simulator.

Abstract: Disclosed are techniques for simulating a multiprocessor system is disclosed. Aspects of the present invention are based on such an observation that most memory accesses from different simulated processors do not conflict, and therefore the conservative policy for performing synchronization of all the memory accesses can waste a large amount of processing time. By identifying possibly conflicting memory accesses and only performing synchronization of these memory accesses, the synchronization cost can be reduced considerably. Since the function simulator is able to operate faster and to perform the same memory accesses, the possibly conflicting memory accesses can be identified by first executing the function simulator.

Abstract: A system and method is provided for distributed relational databases for parallel sorting of a relation wherein the relation is a set of tuples to be sorted on multiple sort sites which completely decouples the return phase from the sort phase in order to eliminate the merge phase. The method involves selecting one coordinator site from any of the available logical sites, then generating and sorting a local sample on each of the available storage sites before sending the local random sample from each storage site to the designated coordinator site wherein the local random samples are merged to provide a single global sample. The coordinator site determines the global interval key values based on the global sample. The interval key values being determined such that each interval fits in a single sort site's main memory, wherein the tuples between two interval key values define the interval.

Abstract: A fast method for sorting data in a distributed data processing system is disclosed. Each processor P.sub.1 12i locally sorts its data into a local sorted file S.sub.i 34i, simultaneously producing an index to the sorted data and a file of key data records R' 32 each comprising a key value paired with the processor's identifier. Each processor produces a distribution table DT.sub.i 28i of its key values using the index, and sends the table to acoordinator processor 18 which merges the processors' tables into a global distribution table GST 30. The global distribution table assigns subranges of key values to the processors, and is broadcast back to them. Each processor then sends each paired key value and processor identifier to the processor assigned by the global distribution table to handle the subrange containing that key value. The processors receive and merge the incoming key data records simultaneously as they send such pairs to other processors. An output stream V.sub.