c ○ 2001 Kluwer Academic Publishers. Manufactured in The Ne(8)

Abstract. A data cube is a popular organization for summary data. A cube is simply a multidimensional structure that contains in each cell an aggregate value, i.e., the result of applying an aggregate function to an underlying relation. In practical situat

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WUBARBARAFigure2.Partitioningalgorithm.

oneandproceedstoclassifyeachchunk,furtherdividingitifnecessary,untilthechunkisdeclaredSTAT-SPARSE,STAT-NULLorSTAT-MODL.Itisworthnoticingthatthealgorithmwillreadthenumberofcellsinthecorecuboidintomemoryonlyonce.Theneachchunkthatisneithersparsenornullwillbereadintomemory(withitsrespectivecells)andprocessed(subdivided,modeled)untilnomoreprocessingisneededforthechunk.Ifeachchunk tsinmemory,thenitisguaranteedthattheeachcellwillbereadintomemoryonlyonce,makingtheinputactivityequivalenttotwopassesofthedataandthewriteactivityalsoequivalenttotwopassesofthedata.Ifachunkdoesnot tinmemoryseveralreadsandwritestothechunkwillbeneeded,makingthetotalreadactivitylooselyboundbyMAXLEVELnumberofpassesthroughthedata.(Duringthisprocess,whena