Transcription of Introduction to Hash Tables
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An Introduction to Hash TablesShaun KaufmannFarm Credit CanadaThispresentationwilladdressfourmai nquestions: Whatarehashesandhowdotheywork? Whatyoucanusethemfor? Whatkindofperformancegainscanhashesprovi de? HowdoIusehashesinSAS?AgendaBeforeweintro ducehashes(hashtables),therearethreeconc eptsthatarehelpfultofacilitateunderstand ing: Whatisadatastructure? WhatistheProgramDataVector? Whatisanobjectinregardtoobjectorientedpr ogramming?Before we adatastructureisaparticularwayofstoringa ndorganizingdatainacomputersothatitcanbe usedefficiently. Adatastructurecanbethoughtofasbeingiscon structedfromdatatypes.(numericandcharact er). Thesimplestdatastructureistheone-dimensi onal(linear)array, StructuresOne Dimensional Array Theprogramdatavectorisastorageplaceinmem orythatcontainsallofthevariablesencounte redbythedatastep.
Think FAST! Use Memory Tables (Hashing) for Faster Merging. SUGI 31 Paper 244-31 Gregg P. Snell, Data Savant Consulting, Shawnee, KS Find() the power of Hash - How, Why and When to use the SAS® Hash Object. John Blackwell, NESUG 2010. SAS Hash Object Programming Made Easy. Michele M. Burlew. SAS Press 2012. Better Hashing in SAS 9.2.
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