tuple relation

Question

consider the relation r1(P,Q,R) and r2(R,S,T) with primary key P and R respectively. r1 contain 2000 tuples and r2 2500 tuples. max size of natural joint of r1 and r2..? plz explain..

Comments

The max size will be Min $(2000, 2500) = 2000$ tuples.

Here is the reference. 

Answer 1

See here R is common in both the relation .Also R is key in the second relation .In second relation R will have 2500 distinct value.

Also Relation r1 has 2000 tuple .So here every tuple in relation r1 will map with the relation r2 .So it will give result 2000 tuple.

So Maximum size of R1⋈  R2 =2000

Also Minimum tuple in R1⋈  R2 =2000

Comments

I should provide one line for answering this question.Then only it will be clear .Instead of up voting you down voting the answer.Ok No problem.If you have still any doubt you can ask.

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thanxxxx manojk i got it now....:)

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thank you .