The Data WareHouse ETL Toolkit - Chapter 05

8/9/2019 The Data WareHouse ETL Toolkit - Chapter 05

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VSV Training

Chapter 5: Delivering Dimension

TablesPrepared By: Kien Tran

Date: 09/01/2008


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5.1 The Basic Structure ! a

Di"ensin#$$ di"ensins shu$d %e physica$$y %ui$t tha&e the "ini"a$ set ! c"pnents

# pri"ary 'ey (surrgate)

*ne r "re natura$ 'eysSet ! descripti&e attri%utes


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5.1 The Basic Structure ! aDi"ensin (Pr%$e"s ! +eneratingSurrgate Keys),nte$$igent r s"art 'eys !ai$ (surrgate 'ey) !r

the !$$-ing reasns:

By denitin

Per!r"ance

Data type "is"atch

Dependency n surce syste"etergeneus surces


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5.2 The +rain ! a Di"ensin

Di"ensina$ "de$ers !reuent$y re!er t thegrain ! a di"ensin.


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5. The Basic ad P$an !r aDi"ensinDi"ensin ta%$es are de3nr"a$i4ed at

ta%$es.

,! a di"ensin is nr"a$i4ed6 the hierarchiescreate a characteristic structure 'n-n as asn-a'e


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5.7 $at Di"ensins and Sn-a'ed

Di"ensins


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5.7 $at Di"ensins and

Sn-a'ed Di"ensins (cnt)


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5.5 Date and Ti"e Di"ensins

Virtua$$y e&ery !act ta%$e has ne r "reti"e3re$ated di"ensin !reign 'eys.


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5.5 Date and Ti"e Di"ensins

(cnt)


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5. Big Di"ensins

The "st interesting di"ensins in a data-arehuse are the %ig6 -ide di"ensins.

The rea$$y %ig di"ensins a$"st a$-ays are

deri&ed !r" "u$tip$e surces.


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5. Big Di"ensins (cnt)


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5. S"a$$ Di"ensins

;any ! the di"ensins in a data -arehuseare tiny $'up ta%$es -ith n$y a !e- recrdsand ne r t- c$u"ns.


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5.8 *ne Di"ensin r T-


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5.9 Di"ensina$


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5.9 Di"ensina$


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5.9 Di"ensina$


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5.10 Di"ensins as Su%

di"ensins ! #nther Di"ensin-e ha&e s"eti"es re!erred t these su%

di"ensins as utriggers.


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5.11 Degenerate Di"ensinsact ta%$e "ay cntain degenerate di"ensin

(rder nu"%er) -hich is nt additi&e %ut "redescripti&e.


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5.12 S$-$y =hanging

Di"ensins>hen the data -arehuse recei&esnticatin that an e?isting r- in adi"ensin has three %asic respnses: Type 16

Type 26 and Type s$-$y changing.


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5.12.1 Type 1 S$-$y =hanging

Di"ensin (*&er-rite)# si"p$e &er-rite ! ne r "re attri%utes

in an e?isting di"ensin recrd.


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Di"ensin (Partitining istry)The standard %asic techniue !r accurate$ytrac'ing changes in di"ensina$ entities andassciating the" crrect$y -ith !act ta%$es.


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Di"ensin (Partitining istry)(cnt)


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5.12.2 Precise Ti"e Sta"ping ! a

Type 2 S$-$y =hanging Di"ensin(cnt)T add the !$$-ing &e e$ds t di"ensin

ta%$es prcessed -ith Type 2 $gic:

=a$endar Date !reign 'ey (date ! change)


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5.12.2 Precise Ti"e Sta"ping ! a

Type 2 S$-$y =hanging Di"ensin(cnt)


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5.12. Type S$-$y =hangingDi"ensin (#$ternate


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5.1 y%rid S$-$y =hanging

Di"ensins


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5.17 ate3#rri&ing Di"ensin


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5.15 ;u$ti&a$ued Di"ensins and

Bridge Ta%$es


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5.15 ;u$ti&a$ued Di"ensins and

Bridge Ta%$es


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5.15.1 #d"inistering the >eightingactrs


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5.15.2 Ti"e3Varying Bridge Ta%$es


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5.15.2 Ti"e3Varying Bridge Ta%$es


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5.1


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5.1


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5.1 Technica$ te:P*P#T,+,@


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5.18 sing Psitina$ #ttri%utes in a

Di"ensin t


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The Data WareHouse ETL Toolkit - Chapter 05

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