Assignment
Consider following relations”
Question 1: If the relations are fragmented into R1 and R2 then comment on the completeness and disjointness of the relations
- R1 = σ RESP = “Manager” OR RESP = “Engineer”(ASG)
- R1 = σ TITLE < “Programmer”(EMP)
- R1 = σ Salary < 30000 (PAY)
R2= σ RESP < “Engineer” (R)
R2= σ TITLE <= “Syst_Anal.”(EMP)
R2= σ Salary ≥ 30000 (PAY)
Question 2:
Assume P1: SAL < 27000 and P2: Sal >= 27000 are two simple predicates. Fragment PAY relation based on P1 and P2. Using these fragments perform fragmentation of EMP and show completeness, disjointness and reconstruction on fragmentation of emP.
Question 3:
Consider the following query based on above relations:
Select ENAME, PNAME
From EMP E, ASG A, PROJ P
Where E.ENO = A.ENO
And A.PNO = P.PNO
And (TITLE = “Elec. Eng” OR A.PNO < “P3”)
- Write relational Algebra expression fot the query
- Draw the canonical tree
- Obtain optimized tree
Question 4:
Simplify the following query:
Select ENO from ASG
Where RESP = ‘Analyst’
and NOT (PNO =”P2” or DUR = 12)
and NOT PNO =”P2”
or DUR = 12
Question 5:
In above relations if PFOJ is horizontally fragmented using the queries:
PROJ1: Select * from PROJ where PNO <= ’P3’
PROJ2: Select * from PROJ where PNO > ’P3’
Transform the following query into a reduced query on fragments:
Select BUGET from PROJ, ASG
Where PROJ.PNO = ASG.PNO
And PNO = “P4”
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