Describe the nested-loop join and block-nested loop join, Database Management System

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Describe the nested-loop join and block-nested loop join. 

 Ans:   The block nested- loop join algorithm is as described below:   

 for every block Br of relation R do begin       

   for every block Bs of  relation S do begin    

    for every tuple tr in Br do begin    

     for every tuple ts in Bs do begin   

      test pair (tr,ts) to see if they satisfy the join  

     condition                                      

        if they do, add tr.ts to the result  

     end

    end

   end

 end          

  The nested-loop from algorithm is like this: 

  for every tuple tr in relation R do begin

                for every tuple ts in relation S do begin

   test pair (tr,ts) to see if they satisfy the join condition   

    if they do, add tr.ts to the result

                     end

      end


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