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Database Comparisons: An Overview Comparison Flat File Hierarchical Network Relational Object-Oriented Hybrid Timeframe Late 1950’searly 1960’s Mid 1960’searly 1970’s Late 1960’smid 1970’s Early 1970’spresent Late 1980’spresent Late 1960’searly 1970’s (Nested) Database Evolution Acronym 1st Generation 2nd Generation 2nd Generation 3rd Generation 4th Generation DBF DBMS DBMS RDBMS Description File orientation & navigation; file structures & proprietary program interfaces Hierarchical orientation & navigation; hierarchies of related records & standard interfaces Network orientation & navigation; uses hierarchicallyarranged data with the exception that child tables can have more than one parent; standard interfaces Relational orientation; data retrieved by unique keys; relationships expressed through matching keys; physical organization of data managed by RDBMS OODBS, ODBMS or OODBMS Object orientation; active, distributed processing & more powerful operators; uses objectoriented programming to combine data structures with functions to create re-usable objects Network of interrelated lists; looks like several trees that share branches; children have multiple parents and parents have multiple children Data is stored in relations (tables); relationships maintained by placing a key field value of one record as an attribute in the related record Physical Structure 6/28/2017 Flat file; onedimensional; frequently in tabular format; oftentimes multiple copies of the same data were maintained, each copy sorted in a different way Tree; parent-child relationships; single table acts as the “root” of the database from which other tables “branch” out; child can only have one parent, but a parent can have multiple children Modeling & creation of data as objects; store objects and operations to be performed on data; applications interact with object managers which work through object servers to gain access to object stores Late 1990’spresent (Object-Relational) 4th Generation O-R, ORDB or ORDBMS Nested: database/operating system with tool for data retrieval built in Object-Relational: relational databases that have evolved to add object-oriented features Organize information common to relational tabular structures; subsume the relational database model 1 Database Comparisons: An Overview Diagram Programming Languages Used See pp. 8 Assembler, Fortran, COBOL; spreadsheets use non-algorithmic programming language See pp. 9 Commands embedded in programming languages; COBOL, PL1, Fortran, ADS & Assembler See pp. 10 Commands embedded in programming languages; COBOL, PL1, Fortran, ADS & Assembler See pp. 11 SQL, ODBC Structural Changes If new fields were added to the file, every program that accessed that file had to be changed & data files would have to be converted Inflexible (once data is organized in a particular way, difficult to change); data reorganization complicated; requires careful design Inflexible (once data is organized in a particular way, difficult to change); data reorganization complicated; requires careful design Relationships No structured interrelationship between its data records Linked lists using pointers stored in the parent/child records to navigate through the records; pointers could be a disk address, the key field, or other random access Uses series of linked lists to implement relationships between records; each list has an owner record & possibly many member records; a single record can Flexible; because tables are subjectspecific & key fields relate one entity to another, both the data & the database structure can be easily modified & manipulated; programs independent of data format which yields flexibility when modifications are needed Uses key fields to link data in many different ways; supports one-toone, one-to-many & many-to-many relationships 6/28/2017 Java, C++, Smalltalk, Ada, Object Pascal, Objective DRAGOON, BETA, Emerald, POOL, Eiffel, Seif, Oblog, ESP. Loops, Visual Basic, POLKA & Python Flexible; programs are built using chunks or modules consisting of preassembled code & data which makes programming easier & faster; changes are made in the underlying code rather than in the design or structure of the database Relational: SQL3, ODBC, JDBC Defines software pieces, object types, actions/methods & the interrelationships between these objects; allows objects to be re-used for different purposes Primarily a relational structure with object-oriented features included Object-Oriented: Java, C++, Smalltalk, etc. Cartridges, DataBlades, & Extenders are modules that build on the object/relational infrastructure; they consist of types, data structures, functions, & data & often include special developer interfaces or prebuilt applications 2 Database Comparisons: An Overview technique; start at root and work down the tree to reach target data; supports one-toone & one-to-many relationships Advantages 6/28/2017 First method for converting raw data into usable information Easily shows oneto-one & one-tomany relationships; More efficient than the flat file model b/c less need for redundant data either be the owner or a member of several lists of various types; supports one-toone, one-to-many, & many-to-many relationships Network model solves problem of data redundancy by representing relationships in terms of sets rather than hierarchy; allowed complex data structures to be built; very efficient in storage & fast; better job with many-to-many relationships More easily visualize data organization & relationships; ease of design & userfriendly GUI interfaces; modern query tools & report generators; ease of data entry; tables represent a single subject; no duplicate data which reduces errors & improves consistency & eases database maintenance; relationships increase data integrity; more information from same data due to file integration; new & one-time requests easily accommodated; customized, menudriven interfaces can be easily Using OOP (objectoriented programming), ability to model, store & manipulate complex data (i.e. multimedia); support for special operations common to niche markets not well supported by more mainstream database engines (i.e. CAD/CAM & document management); supports data structures for arrays which are useful for waveform data such as EKGs and EEGs; persistence, secondary storage management; concurrency; recovery & ad hoc query facilities; when using OOP, Supports SQL; based on relational model so familiar to the user, yet provides some object-oriented features & benefits 3 Database Comparisons: An Overview developed; concurrent access to the data; increased productivity; application code generators; referential integrity controls; transactional integrity ensures that incomplete transactions do not occur; optimization of storage & database operation execution times; database users don’t corrupt each other’s work; scalable (can spread load across multiple CPUs or servers); best for data collection & querying; allows built-in validation; define & store schema (DB structure), load initial data, provide a variety of access methods, add, modify & delete data, provide multiple views of the data, provide security features, 6/28/2017 no need to translate into a database sublanguage (i.e. SQL, ODBC or JDBC) which means 1) writing less code (as much as 40% less) & 2) performance is faster b/c already in the correct format & doesn’t have to be translated (but this depends on complexity of data); best used for information analysis focusing on capability to navigate through & analyze large volumes of data (i.e. production planning, network planning, financial engineering); applications are very dynamic and schemas very complex; supports diverse data types; rather than force fitting all information into a handful of predefined data types (as in 4 Database Comparisons: An Overview facilitate backup and recovery Disadvantages 6/28/2017 Flat file environment created program/data dependence meaning that changes in the format of the data also required changes in all the programs that accessed the data; for any new analyses of the data in the form of a written report, No support for many-to-many relationships; user must know how the tree is structured to find anything; cannot add a record to a child table until it has been incorporated into the parent table; still creates data duplication More difficult to navigate and visualize compared to the hierarchical model; model difficult to implement and maintain; most implementations were used by programmers rather than endusers; had to have an understanding of how the database was Initially, had slow performance in 70’s & 80’s, but today’s more powerful machines speed up performance; wide price range, can be expensive; additional hardware might be required (i.e. faster CPU, more memory and disk space); high impact of failure due to centralization and RDBMS), object databases allow developers to define & use data types that directly reflect the real solution; ODBMS figures out how to physically configure & store information; today, objects & object containers go through a translation known as mapping to work directly with SQLbased relational databases; some modern object databases also support SQL; provides integration Due to time and cost involved, many hesitate to convert existing DBMS to OODBMS; lack of familiarity; most programmers understand RDBMS better than ODBMS; inertia (easier to use what you know); technology & business fear (most ODBMS vendors are small O-R databases force fits objects into a limited physical typing model required by their relational core design; O-R databases offer full SQL compliance, but limited object capabilities 5 Database Comparisons: An Overview new programs had to be written or existing programs had to be modified which seriously affected productivity for programmers & end-users; record descriptions & access methods for each file must be coded in every program that accessed the file; heavy conversion & enhancement workload; flat files need to store excessive amounts of redundant data; more than one subject; duplicate data; validation is manual Examples MS Excel; VisiCalc; Lotus 1-2-3; VP-Planner; Quattro; Symphony; MultiPlan IMS (Information Management System) by IBM Status Today Limited usage (i.e. Limited usage (i.e. 6/28/2017 structured in order to retrieve, insert, update or delete records; required a lot of programming to use successfully non-duplication of data; sophisticated design and programming required for some products; additional user training may be needed due to added system capabilities; backup and recovery are more difficult due to concurrency and complexity; security is more critical and complicated due to shared usage of central database Satellite communications, airline reservations; IDMS (Integrated Database Management System) from Cullinet Limited usage (i.e. Oracle, Informix, Ingres, Sybase, DB2, MS Access, FileMaker Pro, Visual FoxPro, SQL Server, MySQL (free), PostgreSQL (free) Most popular companies (is the risk worth the technological benefits?); not enough object developers; performance can suffer when developers use haphazard object design; reliability & availability suffered in the past due to lack of investment in management tools; past objectoriented databases did not support SQL which was the standard query language of the day; requires tightly coupled language interface & ability to handle the creation & evolution of schema without a lot of programmer intervention ObjectStore, Versant, O2, Gemstone, ONTOS, POET, Objectivity/DB, Jasmine, Matisse Gaining popularity; Oracle8, IBM’s UDB, Sybase Appears that all 6 Database Comparisons: An Overview spreadsheets, address books, bulk email used by spammers) 6/28/2017 Windows file structure) still used in satellite communications & airline reservation systems) DBMS in use today as a result of technical development efforts to ensure that advances such as object orientation, web serving, etc. appear quickly & reliably growing at a rate of 30-40% each year; will see mostly in new development relational systems of the future will be object-relational or RDBMS will coexist side-by-side ODBMS 7