Traditional File System vs DBMS
Adatabaseisacollectionofinterrelateddata'sstoredinadatabaseserver;these
data'swillbestoredintheformoftables.Theprimaryaimofdatabaseistoprovidea
waytostoreandretrievedatabaseinformationinfastandefficientmanner.
There are number of characteristics that differs from traditional file management
system.Infilesystemapproach,eachuserdefinesandimplementstheneededfilesfor
aspecificapplicationtorun.Forexampleinsalesdepartmentofanenterprise,One
userwillbemaintainingthedetailsofhowmanysalespersonnelarethereinthesales
departmentandtheirgrades,thesedetailswillbestoredandmaintainedinaseparate
file.
Another user will be maintaining the salesperson salary details working in the
concern,thedetailedsalaryreportwillbestoredandmaintainedinaseparatefile.
Althoughbothoftheusersareinterestedinthedata'softhesalespersonstheywillbe
havingtheirdetailsinaseparatefilesandtheyneeddifferentprogramstomanipulate
theirfiles.Thiswillleadtowastageofspaceandredundancyorreplicationofdata's,
whichmayleadtoconfusion,sharingofdataamongvarioususersisnotpossible,data
inconsistencymayoccur.Thesefileswillnotbehavinganyinterrelationshipamong
thedata'sstoredinthesefiles.Thereforeintraditionalfileprocessingeveryuserwill
bedefiningtheirownconstraintsandimplementthefilesneededfortheapplications.
Indatabaseapproach,asinglerepositoryofdataismaintainedthatisdefinedonce
and then accessed by many users. The fundamental characteristic of database
approachisthatthedatabasesystemnotonlycontainsdata'sbutitcontainscomplete
definitionordescriptionofthedatabasestructureandconstraints.Thesedefinitions
arestoredinasystemcatalog,whichcontainstheinformationaboutthestructureand
definitions of the database. The information stored in the catalog is called the
metadata,itdescribestheprimarydatabase.Hencethisapproachwillworkonany
typeofdatabaseforexample,insurancedatabase,Airlines,bankingdatabase,Finance
details,andEnterpriseinformationdatabase.Butintraditionalfileprocessingsystem
the application is developed for a specific purpose and they will access specific
databaseonly.
Theothermaincharacteristicofthedatabaseisthatitwillallowmultipleusersto
accessthedatabaseatthesametimeandsharingofdataispossible.Thedatabase
must include concurrency control software to ensure that several users trying to
updatethesamedataatthesametime,itshouldmaintaininacontrolledmanner.In
filesystemapproachmanyprogrammerswillbecreatingfilesoveralongperiodand
variousfileshavedifferentformat,invariousapplicationlanguages.
Therefore there is possibility of information getting duplicated, this redundancy is
storingsamedatamultipletimesleadstohighercostsandwastageofspace.Thismay
resultindatainconsistencyintheapplication,thisisbecauseupdateisdonetosome
ofthefilesonlyandnotallthefiles.Moreoverindatabaseapproachmultipleviews
canbecreated.Viewisatailoredrepresentationofinformationcontainedinoneor
more tables. View is also called as "Virtual table" because view does not contain
physicallystoredrecordsandwillnotoccupyanyspace.
Amultiuserdatabasewhoseusershavevarietyofapplicationsmustprovidefacilities
fordefiningmultipleviews.Intraditionalfilesystem,ifanychangesaremadetothe
structureofthefilesifwillaffectalltheprograms,sochangestothestructureofafile
mayrequirechangingofallprogramsthataccessthefile.Butincaseofdatabase
approachthestructureofthedatabaseisstoredseparatelyinthesystemcatalogfrom
the access of the application programs. This property is known as programdata
independence.
Database can be used to provide persistent storage for program objects and data
structures that resulted in object oriented database approach. Traditional systems
sufferedfromimpedancemismatchproblemanddifficultyinaccessingthedata,which
is avoided in object oriented database system. Database can be used to represent
complex relationships among data's as well as to retrieve and update related data
easilyandefficiently.
It is possible to define and enforce integrity constraints for the data's stored in the database. The
database also provides facilities for recovering hardware and software failures. The backup and
recovery subsystem is responsible for recovery. It reduces the application development time
considerably when compared to the file system approach and availability of up-to-date information
of all the users. It also provides security to the data's stored in the database system.
