database concepts and architecture

7/23/2019 Database Concepts and Architecture

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Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Slide 2- 1


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Copyright 2007 Ramez Elmasri and Shamkant B. Navathe

Chapter 2Dataase System Con!epts and

"r!hite!t#re


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$#tline

Data %odels and &heir Categories 'istory o( Data %odels S!hemas) *nstan!es) and States &hree+S!hema "r!hite!t#re Data *ndependen!e DB%S ,ang#ages and *nter(a!es

Dataase System -tilities and &ools Centralized and Client+Server "r!hite!t#res Classi(i!ation o( DB%Ss


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Data %odels

Data Model: " set o( !on!epts to des!rie the structureo( a dataase)

the operations (or manip#lating these str#!t#res) and

!ertain constraintsthat the dataase sho#ld oey.

Data Model Structure and Constraints: Constr#!ts are #sed to de(ine the dataase str#!t#re

Constr#!ts typi!ally in!l#de elements and their data

types/ as ell as gro#ps o( elements e.g. entity, record,

table/) and relationshipsamong s#!h gro#ps Constraints spe!i(y some restri!tions on valid data1 these

!onstraints m#st e en(or!ed at all times


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Data %odels !ontin#ed/

Data Model Operations: &hese operations are #sed (or spe!i(ying dataase

retrievalsand updatesy re(erring to the

!onstr#!ts o( the data model. $perations on the data model may in!l#de basic

model operations e.g. generi! insert) delete)

#pdate/ anduser-defined operations e.g.

!omp#test#dentgpa) #pdateinventory/


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Categories o( Data %odels

Conceptual (high-level se!antic" data !odels: 3rovide !on!epts that are !lose to the ay many #sers

per!eive data. "lso !alled entity-basedorobject-baseddata models./

#h$sical (lo%-level internal" data !odels: 3rovide !on!epts that des!rie details o( ho data is stored

in the !omp#ter. &hese are #s#ally spe!i(ied in an ad+ho!manner thro#gh DB%S design and administration man#als

&!ple!entation (representational" data !odels: 3rovide !on!epts that (all eteen the aove to) #sed y

many !ommer!ial DB%S implementations e.g. relationaldata models #sed in many !ommer!ial systems/.


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S!hemas vers#s *nstan!es

Dataase S!hema4 &he descriptiono( a dataase. *n!l#des des!riptions o( the dataase str#!t#re)

data types) and the !onstraints on the dataase. S!hema Diagram4

"n illustrativedisplay o( most aspe!ts o(/ adataase s!hema.

S!hema Constr#!t4 " componento( the s!hema or an o5e!t ithin

the s!hema) e.g.) S&-DEN&) C$-RSE.


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S!hemas vers#s *nstan!es

Dataase State4 &he a!t#al data stored in a dataase at a

particular moment in time. &his in!l#des the

!olle!tion o( all the data in the dataase. "lso !alled dataase instan!e or o!!#rren!e or

snapshot/. &he term instance is also applied to individ#al

dataase !omponents) e.g. record instance, tableinstance, entity instance


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Dataase S!hema

vs. Dataase State

Dataase State4 Re(ers to the contento( a dataase at a moment

in time.

*nitial Dataase State4 Re(ers to the dataase state hen it is initially

loaded into the system.

6alid State4 " state that satis(ies the str#!t#re and !onstraints

o( the dataase.


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Dataase S!hema

vs. Dataase State !ontin#ed/

Distin!tion &he database schema!hanges very in(re#ently.

&he database state!hanges every time the

dataase is #pdated.

Sche!ais also !alled intension.

Stateis also !alled e+tension.


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E8ample o( a Dataase S!hema



E8ample o( a dataase state



&hree+S!hema "r!hite!t#re

3roposed to s#pport DB%S !hara!teristi!s o(4 #rogra!-data independence,

S#pport o( !ultiple vie%so( the data.

Not e8pli!itly #sed in !ommer!ial DB%S prod#!ts)#t has een #se(#l in e8plaining dataase

system organization



&hree+S!hema "r!hite!t#re

De(ines DB%S s!hemas at threelevels4 &nternal sche!aat the internal level to des!rie physi!al

storage str#!t#res and a!!ess paths e.g inde8es/. &ypi!ally #ses a ph$sicaldata model.

Conceptual sche!aat the !on!ept#al level to des!rie the

str#!t#re and !onstraints (or the hole dataase (or a

!omm#nity o( #sers. -ses a conceptualor an i!ple!entationdata model.

+ternal sche!asat the e8ternal level to des!rie thevario#s #ser vies. -s#ally #ses the same data model as the !on!ept#al s!hema.



&he three+s!hema ar!hite!t#re


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17/53Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Slide 2- 1'

Data *ndependen!e

.ogical Data &ndependence: &he !apa!ity to !hange the !on!ept#al s!hema

itho#t having to !hange the e8ternal s!hemasand their asso!iated appli!ation programs.

#h$sical Data &ndependence: &he !apa!ity to !hange the internal s!hema

itho#t having to !hange the !on!ept#al s!hema.


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19/53Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Slide 2- 1)

DB%S ,ang#ages

Data De(inition ,ang#age DD,/

Data %anip#lation ,ang#age D%,/ 'igh+,evel or Non+pro!ed#ral ,ang#ages4 &hese

in!l#de the relational lang#age S:, %ay e #sed in a standalone ay or may e

emedded in a programming lang#age

,o ,evel or 3ro!ed#ral ,ang#ages4 &hese m#st e emedded in a programming

lang#age


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DB%S ,ang#ages

Data De/inition .anguage (DD.": -sed y the DB" and dataase designers to

spe!i(y the !on!ept#al s!hema o( a dataase.

*n many DB%Ss) the DD, is also #sed to de(ineinternal and e8ternal s!hemas vies/. *n some DB%Ss) separate storage de/inition

language (SD." andvie% de/inition language(0D."are #sed to de(ine internal and e8ternals!hemas. SD, is typi!ally realized via DB%S !ommands

provided to the DB" and dataase designers



DB%S ,ang#ages

Data Manipulation .anguage (DM.": -sed to spe!i(y dataase retrievals and #pdates

D%, !ommands data s#lang#age/ !an e

embeddedin a general+p#rpose programminglang#age host lang#age/) s#!h as C$B$,) C) C=

=) or >ava. " lirary o( (#n!tions !an also e provided to a!!ess

the DB%S (rom a programming lang#age "lternatively) stand+alone D%, !ommands !an e

applied dire!tly !alled a query language/.



&ypes o( D%,

igh .evel or on-procedural .anguage:


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DB%S *nter(a!es

Stand+alone #ery lang#age inter(a!es E8ample4 Entering S:, #eries at the DB%S

intera!tive S:, inter(a!e e.g. S:,A3l#s in

$R"C,E/ 3rogrammer inter(a!es (or emedding D%, in

programming lang#ages

-ser+(riendly inter(a!es %en#+ased) (orms+ased) graphi!s+ased) et!.


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DB%S 3rogramming ,ang#age *nter(a!es

3rogrammer inter(a!es (or emedding D%, in a

programming lang#ages4 !edded pproach4 e.g emedded S:, (or C)

C==) et!./) S:,> (or >ava/ #rocedure Call pproach4 e.g. >DBC (or >ava)

$DBC (or other programming lang#ages

Dataase #rogra!!ing .anguage pproach4

e.g. $R"C,E has 3,S:,) a programminglang#age ased on S:,1 lang#age in!orporates

S:, and its data types as integral !omponents


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-ser+


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$ther DB%S *nter(a!es

Spee!h as *np#t and $#tp#t

;e Broser as an inter(a!e

3arametri! inter(a!es) e.g.) ank tellers #sing

(#n!tion keys. *nter(a!es (or the DB"4

Creating #ser a!!o#nts) granting a#thorizations

Setting system parameters

Changing s!hemas or a!!ess paths


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Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Slide 2- 2'

Dataase System -tilities

&o per(orm !ertain (#n!tions s#!h as4 ,oading data stored in (iles into a dataase.

*n!l#des data !onversion tools.

Ba!king #p the dataase periodi!ally on tape. Reorganizing dataase (ile str#!t#res.

Report generation #tilities.

3er(orman!e monitoring #tilities. $ther (#n!tions) s#!h as sorting) #ser monitoring)

data !ompression) et!.


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$ther &ools

Data di!tionary repository4 -sed to store s!hema des!riptions and other

in(ormation s#!h as design de!isions) appli!ation

program des!riptions) #ser in(ormation) #sagestandards) et!.

ctive data dictionar$is a!!essed y DB%S

so(tare and #sersDB".

#assive data dictionar$is a!!essed y#sersDB" only.


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Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Slide 2- 2)

$ther &ools

"ppli!ation Development Environments and

C"SE !omp#ter+aided so(tare engineering/

tools4

E8amples4 3oerB#ilder Syase/

>B#ilder Borland/

>Developer 0 $ra!le/


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Copyright 2007 Ramez Elmasri and Shamkant B. Navathe Slide 2- 3*

&ypi!al DB%S Component %od#les


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" 3hysi!al Centralized "r!hite!t#re


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,ogi!al to+tier !lient server ar!hite!t#re


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Clients

3rovide appropriate inter(a!es thro#gh a !lient

so(tare mod#le to a!!ess and #tilize the vario#s

server reso#r!es.

Clients may e diskless ma!hines or 3Cs or;orkstations ith disks ith only the !lient

so(tare installed.

Conne!ted to the servers via some (orm o( a

netork. ,"N4 lo!al area netork) ireless netork) et!./


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DB%S Server

3rovides dataase #ery and transa!tion servi!es to the!lients

Relational DB%S servers are o(ten !alled S:, servers)#ery servers) or transa!tion servers

"ppli!ations r#nning on !lients #tilize an "ppli!ation3rogram *nter(a!e #&/ to a!!ess server dataases viastandard inter(a!e s#!h as4 $DBC4 $pen Dataase Conne!tivity standard

>DBC4 (or >ava programming a!!ess Client and server m#st install appropriate !lient mod#le

and server mod#le so(tare (or $DBC or >DBC See Chapter G


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&o &ier Client+Server "r!hite!t#re

" !lient program may !onne!t to several DB%Ss)

sometimes !alled the data so#r!es.

*n general) data so#r!es !an e (iles or other

non+DB%S so(tare that manages data. $ther variations o( !lients are possile4 e.g.) in

some o5e!t DB%Ss) more (#n!tionality is

trans(erred to !lients in!l#ding data di!tionary

(#n!tions) optimization and re!overy a!ross

m#ltiple servers) et!.


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&hree &ier Client+Server "r!hite!t#re

Common (or ;e appli!ations

*ntermediate ,ayer !alled "ppli!ation Server or ;e

Server4 Stores the e !onne!tivity so(tare and the #siness logi!

part o( the appli!ation #sed to a!!ess the !orresponding

data (rom the dataase server

"!ts like a !ond#it (or sending partially pro!essed data

eteen the dataase server and the !lient.

&hree+tier "r!hite!t#re Can Enhan!e Se!#rity4 Dataase server only a!!essile via middle tier

Clients !annot dire!tly a!!ess dataase server


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&hree+tier !lient+server ar!hite!t#re


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Classi(i!ation o( DB%Ss

Based on the data model #sed &raditional4 Relational) Netork) 'ierar!hi!al. Emerging4 $5e!t+oriented) $5e!t+relational.

$ther !lassi(i!ations Single+#ser typi!ally #sed ith personal

!omp#ters/vs. m#lti+#ser most DB%Ss/.

Centralized #ses a single !omp#ter ith onedataase/vs. distri#ted #ses m#ltiple !omp#ters) m#ltipledataases/


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Cost !onsiderations (or DB%Ss

Cost Range4 (rom (ree open+so#r!e systems to!on(ig#rations !osting millions o( dollars

E8amples o( (ree relational DB%Ss4 %yS:,) 3ostgreS:,)others

Commer!ial DB%S o((er additional spe!ialized mod#les)e.g. time+series mod#le) spatial data mod#le) do!#mentmod#le) H%, mod#le &hese o((er additional spe!ialized (#n!tionality hen

p#r!hased separately Sometimes !alled !artridges e.g.) in $ra!le/ or lades

Di((erent li!ensing options4 site li!ense) ma8im#m n#mero( !on!#rrent #sers seat li!ense/) single #ser) et!.


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'istory o( Data %odels

Netork %odel

'ierar!hi!al %odel

Relational %odel

$5e!t+oriented Data %odels

$5e!t+Relational %odels


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et%or Model: &he (irst netork DB%S as implemented y

'oneyell in GIJ+IK *DS System/.

"dopted heavily d#e to the s#pport y C$D"SL,Con(eren!e on Data Systems ,ang#ages/C$D"SL, + DB& report o( G7/.

,ater implemented in a large variety o( systems +*D%S C#llinet + no Comp#ter "sso!iates/) D%S00 -nisys/) *%"E '.3. 'elett+3a!kard//)6"H +DB%S Digital E#ipment Corp.) ne8tC$%3":) no '.3./.


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E8ample o( Netork %odel S!hema


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Netork %odel

"dvantages4 Netork %odel is ale to model !omple8

relationships and represents semanti!s o(adddelete on the relationships.

Can handle most sit#ations (or modeling #singre!ord types and relationship types.

,ang#age is navigational1 #ses !onstr#!ts like


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Netork %odel

Disadvantages4 Navigational and pro!ed#ral nat#re o( pro!essing

Dataase !ontains a !omple8 array o( pointers

that thread thro#gh a set o( re!ords. ,ittle s!ope (or a#tomated ?#ery optimization@


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ierarchical Data Model: *nitially implemented in a 5oint e((ort y *B% and

North "meri!an Ro!kell aro#nd GIK. Res#lted

in the *%S (amily o( systems. *B%9s *%S prod#!t had and still has/ a very large

!#stomer ase orldide

'ierar!hi!al model as (ormalized ased on the

*%S system $ther systems ased on this model4 System 2k

S"S in!./


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'ierar!hi!al %odel

"dvantages4 Simple to !onstr#!t and operate

Corresponds to a n#mer o( nat#ral hierar!hi!ally organized

domains) e.g.) organization ?org@/ !hart

,ang#age is simple4 -ses !onstr#!ts like E&) E& -N*:-E) E& NEH&) E&

NEH& ;*&'*N 3"REN&) et!.

Disadvantages4

Navigational and pro!ed#ral nat#re o( pro!essing Dataase is vis#alized as a linear arrangement o( re!ords

,ittle s!ope (or M#ery optimizationM


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elational Model: 3roposed in G70 y E.


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O7ect-oriented Data Models: Several models have een proposed (or implementing in a

dataase system.

$ne set !omprises models o( persistent $+$ 3rogramming

,ang#ages s#!h as C== e.g.) in $B>EC&S&$RE or6ERS"N&/) and Smalltalk e.g.) in E%S&$NE/.

"dditionally) systems like $2) $R*$N at %CC + then

*&"SC"/) *R*S at '.3.+ #sed in $pen $$DB/.

$5e!t Dataase Standard4 $D%+GO) $D%+version 2.0)$D%+version O.0.

Chapters 20 and 2 des!rie this model.


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O7ect-elational Models: %ost Re!ent &rend. Started ith *n(ormi8

-niversal Server.

Relational systems in!orporate !on!epts (romo5e!t dataases leading to o5e!t+relational.

E8empli(ied in the latest versions o( $ra!le+0i)

DB2) and S:, Server and other DB%Ss.

Standards in!l#ded in S:,+GG and e8pe!ted to eenhan!ed in (#t#re S:, standards.

Chapter 22 des!ries this model.


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S#mmary

Data %odels and &heir Categories 'istory o( Data %odels S!hemas) *nstan!es) and States

&hree+S!hema "r!hite!t#re Data *ndependen!e DB%S ,ang#ages and *nter(a!es Dataase System -tilities and &ools Centralized and Client+Server "r!hite!t#res Classi(i!ation o( DB%Ss

database concepts and architecture

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