Full Disjunction
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Full DisjunctionsFull Disjunctions
Itzhak FadidaItzhak FadidaTechnion Israel
Credits for this presentation are due to my colleague Benny Kimelfeld.
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Example – Planning a tourExample – Planning a tour
When we plan a tour we wish to have the maximal information to help us make the correct choices.
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Data Sources – Tourist InformationData Sources – Tourist Information
CountryClimate
Canadadiverse
Bahamastropical
UKtempera
te
ClimatesClimates
CountryCityHotelStars
CanadaToront
oPlaza4
CanadaLondo
nRamad
a3
BahamasNassauHilton
AccommodationsAccommodations
CountryCitySite
CanadaLondo
nAir Show
CanadaMount Logan
UKLondo
nBuckingha
m
UKLondo
nHyde Park
SitesSites
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Natural Join – Providing Natural Join – Providing MaximalMaximal Information Information
SELECTSELECT * * FROMFROM
((ClimatesClimates Natural JoinNatural Join AccommodationsAccommodations)) Natural JoinNatural Join SitesSites
Country
CityClimateHotelStars
Site
CanadaLondon
diverseRamada
3Air Show
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Natural Outer Join – Natural Outer Join – PreservingPreserving Information Information
SELECTSELECT * * FROMFROM
((ClimatesClimates Natural Outer JoinNatural Outer Join AccommodationsAccommodations))
Natural Outer JoinNatural Outer Join SitesSites
Country
CityClimateHotelStars
Site
CanadaToronto
diversePlaza4
CanadaLondon
diverseRamada
3Air Show
CanadaMount Logan
UKLondon
Buckingham
UKLondon
Hyde Park
UKtemperate
Bahamas
Nassau
TropicalHilton
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Tourist Example – Full DisjunctionsTourist Example – Full Disjunctions
SELECTSELECT * * FROMFROM
FD(FD(ClimatesClimates,, AccommodationsAccommodations,, Sites Sites))
Country
CityClimateHotelStars
Site
CanadaToronto
diversePlaza4
CanadaLondon
diverseRamada
3Air Show
CanadadiverseMount Logan
UKLondon
temperate
Buckingham
UKLondon
temperate
Hyde Park
Bahamas
NassautropicalHilton
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The Natural The Natural JoinJoin Operator Operator
CountryClimateCityHotelStarsSite
Climates Accommodations Sites
CountryClimateCanadadiverse
Bahamastropical
UKtemperat
e
Climates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
BahamasNassauHilton
Accommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckinghamUKLondonHyde Park
Sites
⋈ ⋈
CanadadiverseLondonRamad
a3Air
Show
A join tuple corresponds to a set of source tuples
Join consistentJoin consistent
ConnectedConnectedNo Cartesian product
CompleteCompleteOne tuple from each relation
Join consistentJoin consistent
ConnectedConnectedNo Cartesian product
CompleteCompleteOne tuple from each relation
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Natural Join Misses InformationNatural Join Misses Information
CountryClimate
Canadadiverse
Bahamastropical
UKtempera
te
ClimatesClimates
CountryCityHotelStars
CanadaToront
oPlaza4
CanadaLondo
nRamad
a3
BahamasNassauHilton
AccommodationsAccommodations
CountryCitySite
CanadaLondo
nAir Show
CanadaMount Logan
UKLondo
nBuckingha
m
UKLondo
nHyde Park
SitesSitesBahamas is not in SitesSites, so natural join misses it
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Natural Join Misses InformationNatural Join Misses Information
CountryClimate
Canadadiverse
Bahamastropical
UKtempera
te
ClimatesClimates
CountryCityHotelStars
CanadaToront
oPlaza4
CanadaLondo
nRamad
a3
BahamasNassauHilton
AccommodationsAccommodations
CountryCitySite
CanadaLondo
nAir Show
CanadaMount Logan
UKLondo
nBuckingha
m
UKLondo
nHyde Park
SitesSitesBahamas is not in SitesSites, so natural join misses it
Mount Logan is not in a city, hence missed
A looser notion of join is needed—one that enables joining tuples from some of the tables
A looser notion of join is needed—one that enables joining tuples from some of the tables
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Why and What is Full DisjunctionsWhy and What is Full Disjunctions??
The full-disjunction operation is a variation of the join operator that maximally combines join consistent tuples from connected relations, while preserving all information in the relations.
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An Example of a Full DisjunctionAn Example of a Full Disjunction
CountryClimateCanadadiverse
UKtemperate
ClimatesClimates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
AccommodationsAccommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckingham
SitesSites
CountryClimateCityHotelStarsSiteFD(R)
R
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An Example of a Full DisjunctionAn Example of a Full Disjunction
CountryClimateCanadadiverse
UKtemperate
ClimatesClimates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
AccommodationsAccommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckingham
SitesSites
CountryClimateCityHotelStarsSite
CanadadiverseTorontoPlaza4
FD(R)
R
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An Example of a Full DisjunctionAn Example of a Full Disjunction
CountryClimateCanadadiverse
UKtemperate
ClimatesClimates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
AccommodationsAccommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckingham
SitesSites
CountryClimateCityHotelStarsSite
CanadadiverseTorontoPlaza4
CanadadiverseLondonRamad
a3Air Show
FD(R)
R
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An Example of a Full DisjunctionAn Example of a Full Disjunction
CountryClimateCanadadiverse
UKtemperate
ClimatesClimates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
AccommodationsAccommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckingham
SitesSites
CountryClimateCityHotelStarsSite
CanadadiverseTorontoPlaza4
CanadadiverseLondonRamad
a3Air ShowCanadadiverse
Mount Logan
FD(R)
R
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An Example of a Full DisjunctionAn Example of a Full Disjunction
CountryClimateCanadadiverse
UKtemperate
ClimatesClimates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
AccommodationsAccommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckingham
SitesSites
CountryClimateCityHotelStarsSite
CanadadiverseTorontoPlaza4
CanadadiverseLondonRamad
a3Air ShowCanadadiverse
Mount Logan
UKtempera
te
London Buckingha
m
FD(R)
R
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An Example of a Full DisjunctionAn Example of a Full Disjunction
CountryClimateCanadadiverse
UKtemperate
ClimatesClimates
CountryCityHotelStarsCanadaTorontoPlaza4CanadaLondonRamada3
AccommodationsAccommodations
CountryCitySiteCanadaLondonAir Show
CanadaMount Logan
UKLondonBuckingham
SitesSites
CountryClimateCityHotelStarsSite
CanadadiverseTorontoPlaza4
CanadadiverseLondonRamad
a3Air ShowCanadadiverse
Mount Logan
UKtempera
te
London Buckingha
m
FD(R)
R
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Any Questions?