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