CS 4604: Introducon to Database Management...

CS4604:Introduc0ontoDatabaseManagementSystems

B.AdityaPrakashLecture#1:Introduc/on

CourseInforma0on§  Instructor

B.AdityaPrakash,Torg3160F,[email protected]–  OfficeHours:2:30-3:30pmMondaysandWednesdays–  Andbyappointment–  IncludestringCS4604insubjectinanyemailyousendme

§  TeachingAssistants

SorourAmiri,McBryde106,[email protected]–  OfficeHours:TBDShamimulHasan,McBryde106,[email protected]–  WillnotholdregularOfficeHours

§  ClassMee0ngTimeMondayandWednesday,4:00PM-5:15PM,LaveryHall340

§  KeepinginTouchCoursewebsitehUp://courses.cs.vt.edu/~cs4604updatedregularlythroughthesemester–  Piazzalinkonthewebsite

Prakash2016 VTCS4604 2

Textbook§  RequiredDatabaseManagementSystems,byRaghuRamakrishnanandJohannesGehrke.3rdEd.McGrawHill.Webpageforthebook(witherrata)hUp://pages.cs.wisc.edu/~dbbook/

§  Op8onal:–  Garcia-Molina,UllmanandWidom,3rdEd.–  Silberschatz,KorthandSudarshan,6thEd.


Pre-reqsandForce-adds

§  Prerequisites:agradeofCorbeUerinCS3114,seniorstanding

§  Force-addrequests:– Goto:hUps://www.cs.vt.edu/S16Force-Adds– Password:4604bap$– Surveylinkwillworkduringtheen/reclassperiod,forthefirstandsecondlectures

–  Ifyoumissbothlectures,gotoMcB114andfillpaperform,andfindmetogetasignature.


CourseGrading

§  Projectisspreadover3deliverables§  Submithardcopiesofhomeworksandprojectassignmentsatthestartofclassontheduedate

§  Eachclasshasrequiredreading(oncoursewebpage)

§  NoPop-QuizzesJ

Homework 30% 6-7

Midtermexam 20% (Tenta/ve)March2,Wed.,inclass

Finalexam 30% May10,Tue.,3:25pm-5:25pm

Courseproject 20% 3assignments


CourseProject

§  Wewillputprojectoverviewlater(firstprojectassignment)

§  2,or3personsperproject.§  Projectrunstheen/resemesterwithregularassignmentsandafinalimplementa/onassignment.


ClassPolicies§  Makesureyougothroughthedetailedpoliciesonwebsite:

hUp://courses.cs.vt.edu/~cs4604/Spring16/policies.html

§  Lectures:Informmeinadvance,ifyouhavetoleaveaclassearlyorcomelateforanyreason.

§  Latepolicy:4‘slip’days(tobeusedonlyforHWsnotproject)

§  Howtosubmitlate:seewebpage§  Exams:noaidsallowed,except:–  1pagewithyournotes(bothsides),forthemidterm–  2suchpages,forthefinal


WhyStudyDatabases?§  Academic–  Databasesinvolvemanyaspectsofcomputerscience–  Fer/leareaofresearch–  ThreeTuringawardsindatabases

§  Programmer–  aplethoraofapplica/onsinvolveusingandaccessingdatabases

§  Businessman–  Everybodyneedsdatabases=>lotsofmoneytobemade

§  Student–  GetthoselastthreecreditsandIdon’thavetocomebacktoBlacksburgeveragain!

–  Google,Oracle,Microsop,Facebooketc.willhireme!–  Databasessoundcool!–  ???


WhatWillYouLearninCS4604?§  Implementa/on

–  Whatisunder-the-hoodofaDBlikeOracle/MySQL?§  Design

–  Howdoyoumodelyourdataandstructureyourinforma/oninadatabase?

§  Programming–  Howdoyouusethecapabili/esofaDBMS?

§  CS4604achievesabalancebetween–  afirmtheore/calfounda/ontodesigningmoderate-sizeddatabases

–  crea/ng,querying,andimplemen/ngrealis/cdatabasesandconnec/ngthemtoapplica/ons


CourseOutline§  Weeks1–4:Query/

Manipula/onLanguagesandDataModeling–  Rela/onalAlgebra–  Datadefini/on–  ProgrammingwithSQL–  En/ty-Rela/onship(E/R)approach

–  SpecifyingConstraints–  GoodE/Rdesign

§  Weeks5–8:Indexes,ProcessingandOp/miza/on–  Storing–  Hashing/Sor/ng–  QueryOp/miza/on–  NoSQLandHadoop

§  Week9-10:Rela/onalDesign–  Func/onalDependencies–  Normaliza/ontoavoidredundancy

§  Week11-12:ConcurrencyControl–  Transac/ons–  LoggingandRecovery

§  Week13–14:Students’choice–  Prac/ceProblems–  XML–  Dataminingandwarehousing


WhatisthegoalofaDBMS?

§  Electronicrecord-keepingFastandconvenientaccesstoinforma/on§  DBMS==databasemanagementsystem–  `Rela/onal’inthisclass– data+setofinstruc/onstoaccess/manipulatedata


WhatisaDBMS?§  FeaturesofaDBMS–  Supportmassiveamountsofdata–  Persistentstorage–  Efficientandconvenientaccess–  Secure,concurrent,andatomicaccess

§  Examples?–  Searchengines,bankingsystems,airlinereserva/ons,corporaterecords,payrolls,salesinventories.

–  Newapplica/ons:Wikis,social/biological/mul/media/scien/fic/geographicdata,heterogeneousdata.


FeaturesofaDBMS•  Supportmassiveamountsofdata

–  Giga/tera/petabytes–  Fartoobigformainmemory

•  Persistentstorage–  Programsupdate,query,manipulatedata.–  Datacon/nuestolivelongaperprogramfinishes.

•  Efficientandconvenientaccess–  Efficient:donotsearchen/redatabasetoansweraquery.–  Convenient:allowuserstoquerythedataaseasilyaspossible.

•  Secure,concurrent,andatomicaccess–  Allowmul/pleuserstoaccessdatabasesimultaneously.–  Allowauseraccesstoonlytoauthorizeddata.–  Providesomeguaranteeofreliabilityagainstsystemfailures.


ExampleScenario

§  Students,takingclasses,obtaininggrades– FindmyGPA– <andotherad-hocqueries>


Obvioussolu0on1:Folders

§  Advantages?– Cheap;Easy-to-use

§  Disadvantages?– Noad-hocqueries– Nosharing– LargePhysicalfoot-print


ObviousSolu0on++

§  FlatfilesandC(C++,Java…)programs– E.g.one(ormore)UNIX/DOSfiles,withstudentrecordsandtheircourses


ObviousSolu0on++

§  Layoutforstudentrecords?– CSV(‘comma-separated-values’) Hermione Grainger,123,Potions,A

Draco Malfoy,111,Potions,B

Harry Potter,234,Potions,A

Ron Weasley,345,Potions,C


ObviousSolu0on++

§  Layoutforstudentrecords?– Otherpossibili/eslikeHermione Grainger,123 123,Potions,A

Draco Malfoy,111 111,Potions,B

Harry Potter,234 234,Potions,A

Ron Weasley,345 345,Potions,C


Problems?

§  inconvenientaccesstodata(need‘C++’exper/ze,plusknowledgeoffile-layout)–  dataisola/on

§  dataredundancy(andinconsistencies)§  integrityproblems§  atomicityproblems§  concurrent-accessproblems§  securityproblems§  …….


Problems-Why?

§  Twomainreasons:– file-layoutdescrip/onisburiedwithintheCprogramsand

–  thereisnosupportfortransac/ons(concurrencyandrecovery)


DBMSshandleexactlythesetwoproblems

ExampleScenario§  RDBMS=“Rela/onal”DBMS§  Therela/onalmodelusesrela/onsortablestostructuredata§  ClassListrela/on:

§  Rela/onseparatesthelogicalview(externals)fromthephysicalview(internals)

§  Simplequerylanguages(SQL)foraccessing/modifyingdata–  FindallstudentswhosegradesarebeUerthanB.–  SELECTStudentFROMClassListWHEREGrade>“B”

Student Course Grade

HermioneGrainger Po/ons A

DracoMalfoy Po/ons B

HarryPoUer Po/ons A

RonWeasley Po/ons C


DBMSArchitecture


Transac0onProcessing§  Oneormoredatabaseopera/onsaregroupedintoa“transac/on”

§  Transac/onsshouldmeetthe“ACIDtest”– Atomicity:All-or-nothingexecu/onoftransac/ons.

– Consistency:Databaseshaveconsistencyrules(e.g.whatdataisvalid).Atransac/onshouldNOTviolatethedatabase’sconsistency.Ifitdoes,itneedstoberolledback.

– Isola/on:Eachtransac/onmustappeartobeexecutedasifnoothertransac/onisexecu/ngatthesame/me.

– Durability:Anychangeatransac/onmakestothedatabaseshouldpersistandnotbelost.



Disadvantagesover(flat)files?


Disadvantagesover(flat)files

§  Price§  addi/onalexper/se(SQL/DBA)(hence:over-killforsmall,single-userdatasetsBut:mobilephones(eg.,android)usesqlite)

ABriefHistoryofDBMS§  Theearliestdatabases(1960s)evolvedfromfilesystems

–  Filesystems•  Allowstorageoflargeamountsofdataoveralongperiodof/me•  Filesystemsdonotsupport:

–  Efficientaccessofdataitemswhoseloca/oninapar/cularfileisnotknown

–  Logicalstructureofdataislimitedtocrea/onofdirectorystructures–  Concurrentaccess:Mul/pleusersmodifyingasinglefilegeneratenon-uniformresults

•  Naviga/onalandhierarchical•  UserprogrammedthequeriesbywalkingfromnodetonodeintheDBMS.

§  Rela/onalDBMS(1970stonow)–  Viewdatabaseintermsofrela/onsortables–  High-levelqueryanddefini/onlanguagessuchasSQL–  Allowusertospecifywhat(s)hewants,nothowtogetwhat(s)hewants

§  Object-orientedDBMS(1980s)–  Inspiredbyobject-orientedlanguages–  Object-rela/onalDBMS


TheDBMSIndustry§  ADBMSisasopwaresystem.

§  MajorDBMSvendors:Oracle,Microsop,IBM,Sybase

§  Free/Open-sourceDBMS:MySQL,PostgreSQL,Firebird.–  UsedbycompaniessuchasGoogle,Yahoo,Lycos,BASF….

§  Allare“rela/onal”(or“object-rela/onal”)DBMS.

§  Amul0-billiondollarindustry



Fundamentalconcepts

§  3-levelarchitecture§  logicaldataindependence§  physicaldataindependence


3-levelarchitecture

§  viewlevel§  logicallevel§  physicallevel

v1 v2v3


3-levelarchitecture

§  viewlevel§  logicallevel:eg.,tables– STUDENT(ssn,name)– TAKES(ssn,cid,grade)

§  physicallevel:– howarethesetablesstored,howmanybytes/aUributeetc


3-levelarchitecture

§  viewlevel,eg:– v1:selectssnfromstudent– v2:selectssn,c-idfromtakes

§  logicallevel§  physicallevel


3-levelarchitecture

§  ->hence,physicalandlogicaldataindependence:

§  logicalD.I.:– ???

§  physicalD.I.:– ???


3-levelarchitecture

§  ->hence,physicalandlogicaldataindependence:

§  logicalD.I.:– canadd(drop)column;add/droptable

§  physicalD.I.:– canaddindex;changerecordorder


Databaseusers

§  ‘naive’users§  casualusers§  applica/onprogrammers§  [DBA(Databaseadministrator)]


Casualusers

DBMS

data

andmeta-data=catalog

select*fromstudent


``Naive’’users

Pictorially:

DBMS

data

andmeta-data=catalog

app.(eg.,reportgenerator)


App.programmers

§  thosewhowritetheapplica/ons(likethe‘reportgenerator’)


DBAdministrator(DBA)

§  Du/es?


DBAdministrator(DBA)

§  schemadefini/on(‘logical’level)§  physicalschema(storagestructure,accessmethods

§  schemasmodifica/ons§  gran/ngauthoriza/ons§  integrityconstraintspecifica/on


Overallsystemarchitecture

§  [Users]§  DBMS– queryprocessor– storagemanager–  transac/onmanager

§  [Files]


DDLint.DMLproc.

queryeval.app.pgm(o)

trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.

naive app.pgmr casual DBA users


Overallsystemarchitecture

§  queryprocessor– DMLcompiler– embeddedDMLpre-compiler– DDLinterpreter– Queryevalua/onengine


Overallsystemarchitecture(cont’d)

§  storagemanager– authoriza/onandintegritymanager–  transac/onmanager– buffermanager– filemanager


Overallsystemarchitecture(cont’d)

§  Files– datafiles– datadic/onary=catalog(=meta-data)–  indices– sta/s/caldata


Someexamples:

§  DBAdoingaDDL(datadefini/onlanguage)opera/on,eg.,createtablestudent...


DDLint.DMLproc.


trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.



Someexamples:

§  casualuser,askingforanupdate,eg.:updatestudentsetnameto‘smith’wheressn=‘345’


DDLint.DMLproc.


trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.



DDLint.DMLproc.


trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.



DDLint.DMLproc.


trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.



Someexamples:

§  app.programmer,crea/ngareport,egmain(){....execsql“select*fromstudent”...}


DDLint.DMLproc.


trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.


pgm(src)


Someexamples:

§  ‘naive’user,runningthepreviousapp.


DDLint.DMLproc.


trans.mgr

emb.DML

buff.mgr filemgr

data meta-data

queryproc.

storagemgr.


pgm(src)


Conclusions

§  (rela/onal)DBMSs:electronicrecordkeepers§  customizethemwithcreatetablecommands§  askSQLqueriestoretrieveinfo


Conclusionscontd

mainadvantagesover(flat)files&scripts:§  logical+physicaldataindependence(ie.,flexibilityofaddingnewaUributes,newtablesandindices)

§  concurrencycontrolandrecovery

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CS 4604: Introducon to Database Management...

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