Initial QGM

Q1.CDept=‘mgmt’And

Q1.Grade>=Q2.$1

took

Max

took

Q1 Q2

Q3SELECT Grade FROM took Q3 WHERE Q3.CName=Q1.CName

SELECTMax(Grade) AS GradeFROM Child Q4

Q4

SELECT Q1.SNameFROM took Q1, temp1 Q2WHERE Q1.CDept = ‘mgmt’ AND Q1.Grade >= Q2.$1

temp1SName,CName,CDept,Grade

Grade

CName,Grade

Grade

Performing Feed for the topmost Box

Q1.Grade>=Q2.$1

CDept=‘mgmt’

Max

Q1 Q2

supp

took

distinct

Magic_1

SELECT DISTINCT CName FROM supp

SELECT MAX (Grade) AS GradeFROM Child

SName,CName,CDept,Grade

SName,CName,Grade

SELECT Q1.SNameFROM took Q1, temp1 Q2WHERE Q1.Grade >= Q2.$1

temp1Q4

Grade

Q1.Grade>=Q2.$1

CDept=‘mgmt’

Max

Q1 Q2

supp

took

distinct

Magic_1

DCOBox

SELECT Q4.cName, Q5.$1FROM Magic_1 Q4, temp1 Q5

Q3.CName=Q1.CNameCIBox

SELECT Q3.Grade FROM DCOBox Q3 WHERE Q3.CName = Q1.CName

Q4 Q5

Q3

CName

SELECT Q1.SNameFROM took Q1, CIBox Q2WHERE Q1.Grade >= Q2.$1

SName,CName,Grade

SName,CName,CDept,Grade

CName CName,

Grade

Grade

temp1 Q6

Can merge the C1Box and the topmost box into one box as every tuple in the topmost box joins with atmost one tuple in the C1Box

Q1.Grade>=Q2.GradeQ1.cName=Q2.cName

CDept=‘mgmt’

Max

Q1 Q2

supp

took

distinct

Magic_1

DCOBoxSELECT Q4.cName,Q5.$1FROM Magic_1 Q4, temp1 Q5

Q4 Q5

CName

SELECT Q1.sName FROM supp Q1, DCOBox Q2WHERE Q1.cName=Q2.cName

AND Q1.Grade>=Q2.Grade

temp1

SName,CName,CDept,Grade

SName,CName,Grade

CName

CName,

Grade

Grade

Q6

Starting Point for the Aggregation Box

Max

distinct

Magic_1

DCOBox Q4 Q5

Q4.CName=Q3.CNameQ3

took

CName, Grade

SELECT Q4.CName, Q5.$1 AS GradeFROM Magic_1 Q4, temp1 Q5

temp1CName

CName,Grade

Grade

Q6 SELECTMax(Grade) AS GradeFROM Child Q6

SELECT Grade FROM took Q3 WHERE Q3.CName=Q1.CName

Grade

Performing Feed for the aggregate Box

Max

distinct

Magic_1

DCOBox Q4 Q5

Q1.CName=Q3.CNameQ3

took

CName, Grade

SELECT Q4.CName,Q5.$1From Magic_1 Q4, temp1 Q5

Q7.cName=Q4.cNameCIBox

Q7

DCOBox Q8 Q9

distinct

Magic_2

CName

CName

CName

CName, Grade

CName, Grade

Grade

Grade

temp1

SELECT Grade FROM DCOBox Q7 WHERE Q7.CName = Q4.CName

SELECTMax(Grade) AS GradeFROM Child Q6

Q6

Grade

SELECT Grade FROM took Q3 WHERE Q3.CName = Q1.CName

SELECT Q8.CName, Q9.Grade FROM Magic_2 Q8, Child Q9

Performing Absorb for the aggregate Box – introduce the

Group By and the LOJ

Max

distinct

Magic_1

DCOBox Q4 Q5

Q1.cName=Q3.cNameQ3

took

CName, Grade

CIBoxQ7

DCOBox Q8Q9

distinct

Magic_2

SELECT CName, MAX (Grade) AS GradeFROM Child Q6GROUPBY Q6.CName

Q6

CName

CName

CName

CName, Grade

CName, Grade

Grade

CName, Grade

CName, Grade

SELECT Q4.CName, Q5.Grade FROM Magic_1 Q4 LOJ temp1 Q5 ON CName

temp1

The LOJ is unnecessary here, and the C1Box is also unnecessary.

Max

Q1.CName=Q3.CNameQ3

took

DCOBox Q8 Q9

distinct

Magic_2

Q6

Q1.Grade>=Q2.GradeQ1.CName=Q2.CName

SELECT CName, MAX (Grade) AS GradeFROM Child Q6GROUPBY Q6.CName

CName, Grade

CName, Grade

CName, Grade

GradeCName

SELECT Q1.SNameFROM supp Q1, temp1 Q2WHERE Q1.CName = Q2.CName AND Q1.Grade >= Q2.Grade

Q2Q1

temp1

Starting Point for the bottommost SPJ Box

Q8.CName=Q3.CNameQ3

took

DCOBox Q8 Q9

distinct

Magic_2

CName

Grade

CName, Grade

CName, Grade

SELECT Grade FROM took Q3 WHERE Q3.CName = Q1.CName

SELECT Q8.CName, Q9.Grade FROM Magic_2 Q8, temp2 Q9

temp2

Performing Absorb for the SPJ Box

Q10.CName=Q3.CNameQ3

took

DCOBox Q8 Q9

distinct

Magic_2

Q10 SELECT Q3.CName, Q3.Grade FROM Magic_2 Q10, took Q3 WHERE Q3.CName = Q10.CName

SELECT Q9.CName, Q9.Grade FROM temp2 Q9

CName

CName

CName, Grade

CName, Grade

CName, Grade

temp2

Remove unnecessary DCOBox

Q10.cName=Q3.cNameQ3

took

distinct

Magic_2

Q10

CName, Grade

CName, GradeCName

SELECT Q3.CName, Q3.Grade FROM Magic_2 Q10, took Q3 WHERE Q3.CName = Q10.CName

The Final QGM

Q10.CName=Q3.CNameQ3

took

distinct

Magic_2

Q10

CName, Grade

Max Q6

Q1.Grade>=Q2.GradeQ1.CName=Q2.CName

CDept=‘mgmt’

took

SELECT Q3.CName, Q3.Grade FROM Magic_2 Q10, took Q3 WHERE Q3.CName = Q10.CName

CName, GradeCName

CName

SELECT CName, MAX (Grade) AS GradeFROM Child Q6GROUPBY Q6.CName

SName,CName,CDept,Grade

SName,CName,Grade

CName, Grade

SELECT Q1.sName FROM supp Q1, temp1 Q2WHERE Q1.CName=Q2.CName AND Q1.Grade>=Q2.Grade

Q2Q1

temp1