16841113 DatawareHousing Concepts

7/23/2019 16841113 DatawareHousing Concepts

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DATA WAREHOUSINGDATA WAREHOUSING


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Data Warehousing ConceptsData Warehousing Concepts

What is a Data Warehouse?What is a Data Warehouse? A Data warehouse is a subect!oriente"# integrate"# ti$e!%ar&ing#A Data warehouse is a subect!oriente"# integrate"# ti$e!%ar&ing#

non!%o'ati'e co''ection o( "ata in support o( the $anage$ent)snon!%o'ati'e co''ection o( "ata in support o( the $anage$ent)s"ecision *$a+ing process ,OR-"ecision *$a+ing process ,OR-

Data warehouse is a re'ationa' "atabase (or .uer& an" Ana'&sisData warehouse is a re'ationa' "atabase (or .uer& an" Ana'&sisRather than (or transaction processing/Rather than (or transaction processing/

Subect!oriente",custo$er#pro"ucts#sa'es#etc-Subect!oriente",custo$er#pro"ucts#sa'es#etc- Non!%o'ati'eNon!%o'ati'e Ti$e!%ar&ingTi$e!%ar&ing Integrate"Integrate"

(William.Inmon 1993)(William.Inmon 1993)


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Subect!oriente"Subect!oriente"

A Data Warehouse is organizedA Data Warehouse is organized

around major subjects, such asaround major subjects, such as

customer, supplier, product andcustomer, supplier, product and

sales. Rather than concentrating onsales. Rather than concentrating on

day-to-day operations andday-to-day operations and

transaction processing of antransaction processing of an

organization.organization.


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Integrate"Integrate"

A Data Warehouse is usuallyA Data Warehouse is usually

constructed by integrating multipleconstructed by integrating multiple

heterogeneous sources, such asheterogeneous sources, such as

relational databases, at les, and on-relational databases, at les, and on-line transaction records. data cleaningline transaction records. data cleaning

and data integration techniues areand data integration techniues are

applied to ensure consistency in namingapplied to ensure consistency in namingcon!entions, encoding structures,con!entions, encoding structures,

attribute measures and so on.attribute measures and so on.


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Ti$e 0ariantTi$e 0ariant

Data are stored to pro!ideData are stored to pro!ide

information from a historicalinformation from a historical

perspecti!e "e#ample$ the past % -&'perspecti!e "e#ample$ the past % -&'

years(. )!ery *ey structure in theyears(. )!ery *ey structure in the

data +arehouse contains, eitherdata +arehouse contains, either

implicitly or e#plicitly an element ofimplicitly or e#plicitly an element of

timetime


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Non!0o'ati'eNon!0o'ati'e

A data +arehouse is al+ays a physicallyA data +arehouse is al+ays a physically

separate store of data transformed from theseparate store of data transformed from the

application data found in the operationalapplication data found in the operational

en!ironment. due to this separation, a dataen!ironment. due to this separation, a data+arehouse does not reuire transaction+arehouse does not reuire transaction

processing,reco!ery,and concurrencyprocessing,reco!ery,and concurrency

control mechanisms. it usually reuires onlycontrol mechanisms. it usually reuires only

t+o operations in data accessing $initialt+o operations in data accessing $initialloading loading of data and access of data.loading loading of data and access of data.


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Co$parison o( O1T2 s&ste$s an"Co$parison o( O1T2 s&ste$s an"

"ata warehousing s&ste$s"ata warehousing s&ste$s

OLTP Systems Data warehousing systems

Ho'"s Current "ata Ho'"s Historica' "ata

Stores "etai'e" "ata

stores "etai'e"#'ight'an" high'&

su$$ari3e" "ata

Data is "&na$ic Data is 'arge'& static

Transaction!"ri%en Ana'&sis "ri%en

App'ication !oriente" Subect !oriente"

Supports "a&!to!"a& "ecisions Supports strategic "ecisions

Ser%es 'arge nu$ber o( c'erica'4operationa'users

Ser%es re'ati%e'& 'ow nu$ber o( $anageria'users


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Di$ension 5o"e'ingDi$ension 5o"e'ing

DimensionDimension$ Dimension is a structure$ Dimension is a structure

+hich consists of le!els, and+hich consists of le!els, and

hierarchies is dened on each le!el.hierarchies is dened on each le!el.

)#ample$)#ample$SEX

MALE FEMALE


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Di$ension 5o"e'ingDi$ension 5o"e'ing

)#ample$)#ample$

Profession

Engineer Secretary Teacher

Chemical Civil Eecutive !unior Elementary "igh School

Level #

Level $

Level %


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6ACTS6ACTS

act$ act consists of +hole data +ithact$ act consists of +hole data +ith

primary *ey, foreign *ey relation shipprimary *ey, foreign *ey relation ship

+ith dimensions and also consists of+ith dimensions and also consists of

measures.measures.

here are hree types of factshere are hree types of facts

&.ADD/) A01&.ADD/) A01

2.1)3 ADD/) A012.1)3 ADD/) A01

4.565 ADD/) A014.565 ADD/) A01


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6act 'ess 6act 7 Con(or$ "i$6act 'ess 6act 7 Con(or$ "i$

act less fact is a fact it does notact less fact is a fact it does not

containcontain

3easures.3easures.

A Dimension +hich can share moreA Dimension +hich can share morethan one act is called 0onformthan one act is called 0onform

DimensionDimension

0ollection of 1tar 1chemas and0ollection of 1tar 1chemas and1no+a*e1no+a*e

1chemas is called 7ala#y.1chemas is called 7ala#y.


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Star sche$a 7 Snow ('a+e Sche$aStar sche$a 7 Snow ('a+e Sche$a

1tar schema$1tar schema$

A 0entralized fact table surrounded +ithA 0entralized fact table surrounded +ithdimension tables ha!ing 8rimary, oreign *eydimension tables ha!ing 8rimary, oreign *eyrelation ship bet+een them is called star schema.relation ship bet+een them is called star schema.

1no+ a*e 1chema$1no+ a*e 1chema$

A normalized star schema s called 1no+A normalized star schema s called 1no+a*e 1chemaa*e 1chema

7ala#y$7ala#y$

0ollection of 1tar schemas and sno+ a*e0ollection of 1tar schemas and sno+ a*e1chema is called 7ala#y.1chema is called 7ala#y.


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Star Sche$aStar Sche$a

Fact Ta&le

Profession'Dim

Se'Dim Date'Dim

A((ress Dim

Se )ey

Se

Profession')ey

Profession'class

Title

Level

(isci*line

A((ress )ey

Country

State

City

Date )ey

Current year

Current month

Current wee)

Con(or$ Di$Profession +ey'''''''''''''''''''''''''''''

Se )ey

''''''''''''''''''''''''''''

A((ress )ey

'''''''''''''''''''''''''''''

Date )ey

'''''''''''''''''''''''''''''

' ''''

''''

'''''

Measures ,-umeric.


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Snow 6'a+e Sche$aSnow 6'a+e Sche$a

Fact Ta&leTime Dim

City DimLocation DimSu**lier Dim

/tem Dim

/tem )ey/tem name

Ty*e

Su**lier )ey

Time )ey/tem )ey

Location )ey

''''''

''''''

''''''''''''''''''''

''''''''

0u*ees sol(

1nits sol(

Time )ey2ear

3uarter

Month

(ay

Location )ey

Street

City )ey

Su**lier )ey

Su**lier name

Su**lier a((ressSu**lier ty*e

City )ey

City name

State

CountryPin co(e


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T82ES O6 5A22INGST82ES O6 5A22INGS

9istory9istory

1imple pass through "5one(1imple pass through "5one(

1lo+ly gro+ing target "ull(1lo+ly gro+ing target "ull( 1lo+ly changing dimension1lo+ly changing dimension

"depends("depends(


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T&pes o( SCD9ST&pes o( SCD9S

1lo+ly changing dimension:&1lo+ly changing dimension:&

1lo+ly changing dimension:21lo+ly changing dimension:2

&.&. ime stampingime stamping

2.2. !ersioning!ersioning

4.4. laginglaging 1lo+ly changing dimension:41lo+ly changing dimension:4


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S'ow'& changing Di$ension!:S'ow'& changing Di$ension!:

10D-&$When you does not +ant10D-&$When you does not +ant

9istory9istory

use this *ind of mapping "6nly insertuse this *ind of mapping "6nly insert

elseelse

;pdate ta*es place( it inserts the;pdate ta*es place( it inserts the

ne+ ro+ or ;pdate the e#istingne+ ro+ or ;pdate the e#isting

dimensions.dimensions.


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S'ow'& changing Di$ension!;S'ow'& changing Di$ension!;

10D -2 "ime stamp($10D -2 "ime stamp($ When you +antWhen you +antmaintain full history use this *ind of mapping.maintain full history use this *ind of mapping.

nserts ne+ and changed dimensions. 0reates annserts ne+ and changed dimensions. 0reates an

e


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S'ow'& changing Di$ension!


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Data Warehouse E=ecutionData Warehouse E=ecution

ArchitectureArchitecture ArchitectureArchitecture

DB2/400

Oracle

S! Ser"er

#lat $le%

ODB&

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ODB&

'ati"e

'&era DataWarehou%e

Source S%tem% +! DAA WA+O,S+

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16841113 DatawareHousing Concepts

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