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JOIN ON SELETCT ON JOIN

+1 vote
22 views

if we do JOIN when one of the sides is a SELECT on another JOIN results.

what is the cost??

exemple in 2014

http://courses.cs.tau.ac.il/databases/oldtests/DB1314B-solution.pdf

שאלה 3

סעיף ג

חלק 4

בתשובות הם הכפילו, אבל ראיתי תשובות שבהן לפעולת מקסימום במכנה הוסיפו

V(R,b)

של עמודת הסלקט

asked Feb 3, 2018 by tikitak (2,970 points)

1 Answer

+1 vote

Assuming you're talking about 'iv' (P2):

Notice they used a notation Jn(R.C,Q.H) which is defined earlier on the question (start of that page)

Which in turn is defined like you would expect.

(If you're talking about 'iii' (P1) - I don't see size multiplication in the answers)

answered Feb 3, 2018 by Assaf (31,090 points)
(And Jn(R.C,Q.H) in turn uses sl(R) which contains division by V(R,B) )
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