Homework answers / question archive / Question # 3: Given relations PAY and EMP as  PAY (title , sal)         EMP (eNo, ename, title)   p1: sal < 30000 and p2: sal >= 3000    Let p1 and p2 by two simple predicates

Question # 3: Given relations PAY and EMP as  PAY (title , sal)         EMP (eNo, ename, title)   p1: sal < 30000 and p2: sal >= 3000    Let p1 and p2 by two simple predicates

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Question # 3: Given relations PAY and EMP as  PAY (title , sal)

 

 

 

 

EMP (eNo, ename, title)

 

p1: sal < 30000 and p2: sal >= 3000 

 

Let p1 and p2 by two simple predicates. Perform a horizontal fragmentation of PAY with respect to these predicates to obtain PAY1, and PAY2. Using the fragmentation of PAY, perform further derived horizontal fragmentation for EMP. Show completeness, reconstruction, and disjointness of the fragmentation of EMP.

 

Question # 4:

Consider relations EMP and PAY 

 

PAY (title , sal)

EMP (eNo, ename, title)

 

EMP and PAY are horizontally fragmented as follows:

 

EMP1 = σ title = "Elect.Eng." (EMP)

EMP2 = σ title = "Syst.Anal." (EMP)

EMP3 = σ title = "Mech.Eng." (EMP)

EMP4 = σ title = "Programmer." (EMP)

PAY1 = σ sal >= 30000 (PAY)

PAY2 = σ sal < 30000 (PAY)

Draw the join graph. Is the graph simple or partitioned? If it is partitioned, modify the fragmentation of either EMP or PAY so that the join graph of EMP ? title PAY is simple.