Database & Record StructureDefinitionDatabase ComponentsDatabase FieldsSlide 5Database Records and FilesHypertext DatabaseData StructureTreesTablesDialog DatabaseDialog Database StructureLinear FileInverted FileCreation of Inverted FileSlide 16Linear File: ExampleSlide 18Slide 19IndexingRecord StructureInternet ProtocolsE-mail ProtocolsDatabase & Record StructureDania BilalIS 530Spring 2005DefinitionA database is a collection of information organized in a way that a computer program can quickly retrieve desired pieces of data.Database ComponentsFieldsRecordsFilesDatabase FieldsPieces of information a user can accessAuthorTitleJournal nameAbstractDescriptorsOtherDatabase FieldsFields may have attributes associated with them:Numeric (e.g., accession number)Textual (e.g., author name)Database Records and FilesRecordA collection of fields which constitutes a complete set of informationFileA collection of recordsHypertext DatabaseHypertext was invented by Ted Nelson in the 1960s.In a hypertext database, objects (text, pictures, music, and other media) are linked to each other.Data StructureA scheme for organizing related pieces of information. Basic types of data structuresFiles, records, trees, tablesTreesData is organized in a hierarchical structureEach element is attached to one or more elements that is directly beneath it.Connections between elements ->branchesElements at bottom of a tree with no elements below them -> leavesTablesData is organized in rows and columnsExample: Excel spreadsheetRelational database management systems store data in the form of related tablesAleph system is based on a relational database management system (Oracle)Dialog DatabaseDocuments or surrogates are stored in a linear fileLinear file is transformed into an inverted fileDialog Database StructureLinear fileComposed of document surrogates stored in the IR system in their full, native form.Inverted fileComposed of all words included in document surrogates excluding stop words.Linear FileDocuments have to be searched in their entirety to locate specific information needed.Slow and inefficientInverted FileWords in all documents can be searched instead of the whole text of the documents themselvesFaster and more efficientCreation of Inverted FileA list of words in document surrogates is made.Each word is numbered, including phrases and excluding stop words.Words that are numbered are alphabetized (numbers precede letters)Creation of Inverted FileAlphabetized entries are followed by the document number, field (e.g., AB, DE), and the number of the entry in that field (e.g., entry in abstract as first word)Linear File: Example101The origins of Don Giovanni.Discusses the history and sources Mozart used in his opera Don Giovanni.DE: Mozart, Opera, Historical Analysis.Inverted FileOrigins 101 Ti 2Don 101 Ti 4Giovanni 101 Ti 5Discusses 101 Ab 1History 101 Ab 3Sources 101 Ab 5Mozart 101 Ab 6Used 101 Ab 7…Inverted FileMozart 101 DE 1Opera 101 DE 2Historical 101 DE 3Analysis 101 DE 4Historical Analysis 101 DE 3,4IndexingWords (keywords)Every important word in document is indexedInformation systems, for example, is indexed as 2 separate words and as a phraseInformationSystemsInformation systemsRecord StructureDialog record structure shows every field followed by the information for that field. Fields and structure varies among databasesInternet ProtocolsHttpTelnetFile Transfer Protocol (FTP)Secure FTP (SSH)Web-based FTP (Volspace)E-mail ProtocolsSMTP (Simple Mail Transfer Protocol) Used to send e-mail between servers and between a server and client’s machine over the InternetEmail is retrieved by using a POP, IMAP, or text-based e-mail clientPOP (Post Office Protocol)IMAP (Internet Message Access
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