Multidimensional Expressions MDX is a query language for OLAP database s, much like SQL is a query language for relational databases . It is also a calculation language, with syntax similar to spreadsheet formulas. Background The MultiDimensional eXpressions MDX language provides a specialized syntax for querying and manipulating the multidimensional data stored in OLAP cube s. ref cite web url http www.microsoft.com msj 0899 mdx mdx.aspx title Manipulate and Query OLAP Data Using ADOMD and Multidimensional Expressions publisher Microsoft author Carl Nolan accessdate 2008 03 05 ref While it is possible to translate some of these into traditional SQL, it would frequently require the synthesis of clumsy SQL expressions even for very simple MDX expressions. MDX has been embraced by a wide majority of Comparison of OLAP Servers OLAP vendors and has become the de facto standard for OLAP systems. History MDX was first introduced as part of the OLE DB for OLAP specification in 1997 from Microsoft . It was invented by the group of Microsoft SQL Server SQL Server engineers including Mosha Pasumansky . The specification was quickly followed by commercial release of Microsoft OLAP Services 7.0 in 1998 and later by Microsoft Analysis Services . The latest version of the OLE DB for OLAP specification was issued by Microsoft in 1999. While it was not an open standard, but rather a Microsoft owned specification, it was adopted by the wide range of OLAP vendors. This included both vendors on the server side such as Applix , icCube , MicroStrategy , NCR Corporation NCR , Oracle Corporation , SAS ... article.php 1459531 MDX Essentials Series by William Pearson in the Database Journal Data warehouse Category Online analytical processing Category Query languages de Multidimensional Expressions es Expresiones multidimensionales fr Multidimensional Expressions nl Multidimensional Expressions pl Multidimensional Expressions ru MDX ... more details
Expert subject multiple Mathematics Systems date February 2010 By the term multidimensional systems or m D systems we mean the branch of mathematical systems theory where not only one Variable mathematics variable exists like time , but several independent variables. Important problems like factorization and Stability theory stability have recently attracted the interest of many researchers and practitioners. The reason is that the factorization and stability of m D systems m 1 is not a straightforward extension of the factorization and stability of 1 D systems because for example the fundamental theorem of algebra does not exist in the Ring mathematics ring of m D m 1 polynomials . Applications Multidimensional systems or m D systems are the necessary mathematical background for modern digital image processing with many applications in biomedicine , X ray technology and satellite communications . There are also some studies combining m D systems with partial differential equations PDEs . References cite book editor last Tzafestas editor first S.G. title Multidimensional Systems Techniques and Applications publisher Marcel Dekker location New York date 1986 cite book last Kaczorek first T. title Two Dimensional Linear Systems publisher Springer Verlag series Lecture Notes Contr. and Inform. Sciences volume 68 date 1985 cite book editor last Bose editor first N.K. title Multidimensional Systems Theory, Progress, Directions and Open Problems in Multidimensional Systems publisher D. Reidel Publishing Company location Dordrecht, Holland date 1985 cite book editor last Bose editor first N.K. title Multidimensional Systems Theory and Applications publisher IEEE Press date 1979 Systemstheory stub Category Digital imaging Category Partial differential equations Category Stability theory ... more details
Multiple issues notability April 2008 orphan November 2008 An organization is multidimensional if its ... segment . Introduction The multidimensional organization exhibits the following the overall Performance ... opportunities Cause The most basic reason for the rise of the multidimensional organization is that, due to the fall in costs of information , customers start to behave in multidimensional ways in terms ... books IntroCyb.pdf accessdate 29 September 2010 ref The multidimensional organization also answers the emergence of multidimensional strategies, ref cite journal last Bartlett first C. A. coauthors ... The multidimensional organization is a new organization form, compared to the U form, the M form and the H ... with the matrix organization. Examples of firms with a multidimensional organization are IBM, Microsoft, ASML. ref cite web url http www.ssrn.com title The Emergence of the Multidimensional ... The differences between the multidimensional organization and the matrix organization can be summarized as below class wikitable Matrix organization Multidimensional organization One person may ... to ERP The multidimensional organization implies specific requirements on how transactions are recorded ... to be recorded, not only multidimensional, to allow multiple consolidations to occur simultaneously ... generation of workers Multidimensional organizations are an answer to the new generation of workers .... The multidimensional organization was discussed as early as the 1970s. ref cite journal last Ackoff first R. L. title Towards Flexible Organizations A Multidimensional Design year 1977 journal Omega ... The Concept and Potential of Multidimensional Organizations ref ref cite journal last Prahalad first C. K. coauthors Doz, Y. L. title Strategic Reorientation in the multidimensional organization journal ... multidimensional markets, and a new generation of workers and managers, to create this paradigm shift in organization forms. References Reflist DEFAULTSORT Multidimensional Organization Category ... more details
In statistics , econometrics , and related fields, multidimensional analysis is a data analysis process that groups data into two or more categories data dimension s and measurements. For example, a data set consisting of the number of wins for a single football team at each of several years is a single dimensional in this case, longitudinal data set. A data set consisting of the number of wins for several football teams in a single year is also a single dimensional in this case, cross sectional data set. A data set consisting of the number of wins for several football teams over several years is a two dimensional data set. In many disciplines, two dimensional data sets are also called panel data . ref Madalla, G.S., 2001. u Introduction to Econometrics u , New York Wiley. ref While, strictly speaking, two and higher dimensional data sets are multi dimensional, the term multidimensional tends to be applied only to data sets with three or more dimensions. ref Davies, A. and K. Lahiri, 1995. A new framework for testing rationality and measuring aggregate shocks using panel data. Journal of Econometrics , 68 1 , 205 227. ref For example, some forecast data sets provide forecasts for multiple target periods, conducted by multiple forecasters, and made at multiple horizons. The three dimensions provide more information than can be gleaned from two dimensional panel data sets. References references See also Multidimensional panel data DEFAULTSORT Multidimensional Analysis Category Multivariate statistics stat stub lv Daudzdimensiju anal ze ... more details
Multidimensional scaling MDS is a set of related statistical techniques often used in information visualization for exploring similarities or dissimilarities in data. MDS is a special case of Ordination statistics ordination . An MDS algorithm starts with a matrix mathematics matrix of item item Similarity mathematics similarities , then assigns a location to each item in N dimensional space, where ... matrix Classical multidimensional scaling also known as Torgerson Scaling or Torgerson Gower ... Borg, I., Groenen, P. title Modern Multidimensional Scaling theory and applications publisher Springer Verlag location New York year 2005 pages 207 212 edition 2nd isbn 0387948457 ref Metric multidimensional ... . Non metric multidimensional scaling In contrast to metric MDS, non metric MDS both finds ... SSA is an example of a non metric MDS procedure. Generalized multidimensional scaling An extension of metric multidimensional scaling, in which the target space is an arbitrary smooth non Euclidean space ... cite journal author Bronstein AM, Bronstein MM, Kimmel R title Generalized multidimensional scaling ... name Kruskal Joseph Kruskal Kruskal, J. B. , and Wish, M. 1978 , Multidimensional Scaling , Sage ... marketing Generalized multidimensional scaling GMDS Data clustering Factor analysis Discriminant ... refbegin cite book author Cox, T.F., Cox, M.A.A. title Multidimensional Scaling publisher Chapman and Hall year 2001 cite book author Coxon, Anthony P.M. title The User s Guide to Multidimensional Scaling ... bonn.de doc delbeke delbeke.htm An elementary introduction to multidimensional scaling http www.pavis.org essay multidimensional scaling.html Evaluation of multidimensional scaling algorithms Dead link date February 2011 http www.newmdsx.com NewMDSX Multidimensional Scaling Software http www.visumap.net ... in C by Antonio Gulli DEFAULTSORT Multidimensional Scaling Category Consumer behaviour Category Elections ... Skalierung es Escalamiento multidimensional it Scaling multidimensionale ja pl Skalowanie ... more details
Merge from Database administrator date January 2010 A database is a system intended to organize, store ... database management system s, which store database contents, allowing data creation and maintenance, and search and other access. Architecture Database architecture consists of three levels external ... model relational database model that dominates 21st century databases. ref name date31 harvnb Date .... A single database can have any number of views at the external level. The internal level defines how ... of indirection between internal and external. It provides a common view of the database that is uncomplicated ... into a coherent whole. ref name date31 Database management systems Main Database management system A database management system DBMS consists of software that operates databases, providing storage, access, security, backup and other facilities. Database management systems can be categorized according to the database model that they support, such as relational model relational or XML database ... s that access the database, such as SQL or XQuery , performance trade offs, such as maximum scale ... Access, SQL Server, FileMaker,Oracle,Sybase, dBASE, Clipper,FoxPro etc. Almost every database software comes with an Open Database Connectivity ODBC driver that allows the database to integrate with other ... web url http en.wikibooks.org wiki Design of Main Memory Database System Overview of DBMS title Design of Main Memory Database System Overview of DBMS publisher En.wikibooks.org date accessdate 2010 ... DBMS RDBMS include Data Definition Language DDL for defining the structure of the database, Data Control ... , Firebird database server FireBird Python programming language Python . SQL engine This component ... of objects instead of relational rows. Types unreferenced section date January 2011 Analytical database Analysts may do their work directly against a data warehouse or create a separate analytic database ... are the norm. Distributed database These are databases of local work groups and departments ... more details
Generalized multidimensional scaling GMDS is an extension of metric multidimensional scaling , in which the target space is non Euclidean. In case when the dissimilarities are distances on a surface and the target space is another surface, GMDS allows finding the minimum distortion embedding of one surface into another. GMDS is an emerging research direction. Currently, main applications are recognition of deformable objects e.g. for three dimensional face recognition and texture mapping. References cite journal author Bronstein AM, Bronstein MM, Kimmel R title Generalized multidimensional scaling a framework for isometry invariant partial surface matching journal Proc. Natl. Acad. Sci. U.S.A. volume 103 issue 5 pages 1168 72 year 2006 month January pmid 16432211 pmc 1360551 doi 10.1073 pnas.0508601103 url http www.pnas.org cgi pmidlookup?view long&pmid 16432211 External links http www.cs.technion.ac.il mbron research gmds.html Michael Bronstein s GMDS homepage Category Multivariate statistics ... more details
Orphan date February 2009 The Multidimensional hierarchical toolkit or http www.cs.uni.edu okane source MUMPS MDH mdh.html Multi Dimensional and Hierarchical MDH Database Toolkit is a Linux based, open source d, toolkit of portable software that supports very fast, flexible, multi dimensional and hierarchical storage, retrieval and manipulation of information in databases ranging in size up to 256 terabytes. The package is written in C programming language C and C and is available under the GNU GPL LGPL Free Documentation licenses in source code form. The distribution kit contains demonstration implementations of network capable, interactive text and sequence retrieval tools that function with very large genomic data bases and illustrate the toolkit s capability to manipulate massive data sets of genomic information. Distribution The toolkit is distributed as part of the http www.cs.uni.edu okane source MUMPS MDH compiler.html Mumps Compiler . Versions exist for Linux, Cygwin , and Windows XP . Origins The toolkit is a solution to the problem of manipulating very large, character string indexed, multi dimensional, sparse matrices. It is based on MUMPS also referred to as M , a general purpose programming language that originated in the mid 60 s at the Massachusetts General Hospital . Key features The principal database feature in this project is the global array which permits direct, efficient manipulation of multi dimensional arrays of effectively unlimited size. A global array is a persistent, sparse, undeclared, multi dimensional, string indexed data disk based structure. A global array may appear anywhere an ordinary array reference is permitted and data may be stored at leaf nodes as well as intermediate nodes in the data base array. The number of subscripts in an array reference is limited only by the total length of the array reference with all subscripts expanded to their string values. The toolkit includes several functions to traverse the data base and manipulate ... more details
Refimprove date December 2008 In econometrics , panel data is data observed over two dimensions typically, time and cross sections . A panel data set is termed multidimensional when the phenomenon is observed over three or more dimensions. An example is a data set containing forecasts produced by multiple individuals the first dimension forecasting multiple macroeconomic variables the second dimension at multiple time horizons the third dimension and for multiple target periods the fourth dimension . Analysis of panel data A multidimensional panel with four dimensions can have the form math X isth , i 1, dots, N, s 1, dots, S, t 1, dots, T, h 1, dots, H, , math where i is the individual dimension, s is the series dimension, t is the time dimension, and h is the horizon dimension. A general multidimensional panel data regression model is written as math y isth alpha X sith beta u sith . , math Complex assumptions can be made on the precise structure of the correlations among errors in this model. For example, serial correlation error terms correlated across time has multiple distinct meanings. Error terms can be correlated across time for the same series, individual, and horizon. They can be correlated across time and across series for the same individual and horizon, etc. Similarly, heteroskedasticity can be defined across individuals for the same series, time, and horizon, across individuals and different series for the same time and horizon, etc. Data sets which have a multidimensional panel design Blue Chip Survey of Professional Forecasters Survey of Professional Forecasters ASA NBER See also Panel analysis References http www.cemfi.es arellano Arellano, Manuel . Panel Data Econometrics, Oxford University Press 2003. Hsiao, Cheng, 2003. Analysis of Panel Data, Cambridge University Press. Davies, A. and Lahiri, K., 2000. Re examining the Rational Expectations Hypothesis Using Panel Data on Multi Period Forecasts, Analysis of Panels and Limited Dependent Variable ... more details
unsourced date May 2009 A multidimensional parity check code MDPC is a simple type of error correcting code that operates by arranging the message into a multidimensional grid, and calculating a parity bit parity digit for each row and column. In general, an n dimensional parity scheme can correct n 2 errors. Fact date May 2009 Example Assume that the goal is to transmit the four digit message 1234 , using a two dimensional parity scheme. First the digits of the message are arranged in a rectangular pattern 12 34 Parity bit Parity digits are then calculated by summing each column and row separately 12 3 34 7 46 The eight digit sequence 12334746 is the message that is actually transmitted. If any single error occurs during transmission then this error can not only be detected but can also be corrected as well. Let us suppose that the received message contained an error in the first digit. The receiver rearranges the message into the grid font color red 9 font 2 3 34 7 46 The receiver can see that the first row and also the first column add up incorrectly. Using this knowledge and the assumption that only one error occurred, the receiver can correct the error. In order to handle two errors, a 4 dimensional scheme would be required, at the cost of more parity digits. Decoder An n dimensional parity scheme is only guaranteed to correct up to n 2 errors, as the minimum distance is n 1 . As with all block code s, a soft decision decoder may be able to correct more than this. See also Error detection and correction Forward error correction Low density parity check code Category Error detection and correction ... more details
The Multidimensional Poverty Index MPI was developed in 2010 by Oxford Poverty & Human Development Initiative and the United Nations Development Programme . ref cite news author coauthors title A wealth of data. A useful new way to capture the many aspects of poverty url http www.economist.com node 16693283 quote Aided by the improved availability of survey data about living conditions for households in over 100 developing countries, the researchers have come up with a new index, called the Multidimensional Poverty Index MPI , which the United Nations Development Programme UNDP will use in its next Human Development Report in October. work The Economist date July 29, 2010 accessdate 2010 08 04 ref History The MPI was created for the 20th Anniversary edition of the UNDP Human Development Report and uses different factors to determine poverty beyond income based lists. It uses a range of deprivations that afflict an individual s life. The measure assesses the nature and intensity of poverty at the individual level in education, health outcomes, and standard of living. ref cite web url http www.ophi.org.uk policy multidimensional poverty index title Multidimensional Poverty Index accessdate 2010 08 04 quote publisher Oxford Poverty & Human Development Initiative ref The MPI is an index of acute multidimensional poverty. It reflects deprivations in very rudimentary services and core human functioning for people across 104 countries. Although deeply constrained by data limitations, MPI reveals a different pattern of poverty than income poverty, as it illuminates a different set of deprivations. The MPI has three dimensions health, education, and standard of living. These are measured ... A small Source Alkire, Sabina and Maria Emma Santos. 2010. Multidimensional Poverty Index 2010 Data. Oxford Poverty and Human Development Initiative. Available at www.ophi.org.uk policy multidimensional ... de pobresa multidimensional es ndice de pobreza multidimensional fr Indice de pauvret multidimensionnelle ... more details
Unreferenced date August 2008 In probability theory , the multidimensional Chebyshev s inequality is a generalization of Chebyshev s inequality , which puts a bound on the probability of the event that a random variable differs from its expected value by more than a specified amount. Let X be an N dimensional random vector with expected value math mu mathbb E left X right math and covariance matrix math V mathbb E left left X mu right left X mu right T right . , math If math V math is an invertible matrix i.e., a strictly positive definite matrix , for any real number math t 0 math math mathrm Pr left sqrt left X mu right T , V 1 , left X mu right t right le frac N t 2 math where math N mathrm trace V 1 V math . Proof Since math V math is positive definite, so is math V 1 math . Define the random variable math y left X mu right T , V 1 , left X mu right . math Since math y math is positive, Markov s inequality holds math mathrm Pr left sqrt left X mu right T , V 1 , left X mu right t right mathrm Pr left sqrt y t right mathrm Pr left y t 2 right le frac mathbb E y t 2 . math Finally, math mathbb E y mathbb E left X mu right T , V 1 , left X mu right mathbb E mathrm trace V 1 , left X mu right , left X mu right T mathrm trace V 1 V N . math Category Probabilistic inequalities Category Statistical inequalities ... more details
Orphan date February 2009 A statistical database is a database used for statistics statistical analysis purposes. It is an OLAP instead of OLTP system, although this term precedes that modern decision, and classical statistical databases are often closer to the relational model than the multidimensionaldatabasemultidimensional model commonly used in OLAP systems today. Statistical databases often incorporate support for advanced statistical analysis techniques, such as correlations, which go beyond SQL . They also pose unique security concerns, which were the focus of much research, particularly in the late 1970s and early to mid 1980s. Security in statistical databases In a statistical database, it is often desired to allow query access only to aggregate datas, not individual records. Securing such a database is a difficult problem, since intelligent users can use a combination of aggregate queries to derive information about a single individual. Some common approaches are only allowing aggregate queries SUM, COUNT, AVG, STDEV, etc. rather than returning exact values for sensitive data like income, only return which partition it belongs to e.g. 35k 40k return imprecise counts e.g. rather than 141 records met query, only indicate 130 150 records met it. don t allow overly selective WHERE clauses audit all users queries, so users using system incorrectly can be investigated use ... restrictions on allowable query set sizes will render the database useless as a source of statistical ... trier.de ley db conf ssdbm Statistical and Scientific Database Management SSDBM An important ... E. Denning, Secure statistical databases with random sample queries, ACM Transactions on Database ... de Jonge, Compromising statistical databases responding to queries about means, ACM Transactions on Database ..., Jan Schl rer, A fast procedure for finding a tracker in a statistical database, ACM Transactions on Database Systems, Volume 5, Issue 1 March 1980 . Pages 88 102 Category Databases ... more details
value Information model Multidimensionaldatabase Multi dimensional model Semantic data model ...A database model is the theoretical foundation of a database and fundamentally determines in which manner data can be stored, organized and manipulated in a database system. It thereby defines the infrastructure offered by a particular database system. The most popular example of a database model is the relational model . File Database models.jpg thumb 480px Collage of five types of database models. Overview A database model is a theory or specification describing how a database is structured and used. Several such models have been suggested. Common models include Hierarchical database model Hierarchical ... Various techniques are used to model data structure. Most database systems are built around one particular ... Image Flat File Model.svg thumb 350px Flat File Model. main Flat file database Spreadsheet The flat file database flat or table model consists of a single, two dimensional array of data elements, where ... as a part of a system security database. Each row would have the specific password associated with an individual ... left Hierarchical Model. main Hierarchical model In a hierarchical database hierarchical model , data ... structures were widely used in the early mainframe database management systems, such as the Information ... database operations when a full path as opposed to upward link and sort field is not also included ... Model. main Network model The network database network model defined by the CODASYL specification ... performance, at the expense of operations such as database loading and reorganization. Most object database s use the navigational concept to provide fast navigation across networks of objects ... to make database management systems more independent of any particular application. It is a mathematical ... to as relational database s in fact implement a model that is only an approximation to the mathematical model defined by Codd. Three key terms are used extensively in relational database models relation ... more details
Protein database may refer to Any protein structure database Any protein sequence database Exact names Protein NIH Protein database of the National Institute of Health Protein Database of Bio Synthesis, Inc. disambig ... more details
wiktionarypar DatabaseDatabase may refer to Database , central article discussing the organised collection of data Springfield Elementary School Students DatabaseDatabase , a character on The Simpsons Bibliographic database , in libraries, a collection of bibliographic information on a particular topic Glass database , a collection of glass compositions and related properties disambig ... more details
Database state may refer to Database state, in database technology the set of stored data. Entering, modifying, or deleting information changes the database state. A state that practices Mass surveillance . disambig ... more details
The Diseases Database is a free website that provides information about the relationships between medical conditions, symptoms , and medications . The database is run by Medical Object Oriented Software Enterprises Ltd, a small company based in London , UK . It directly integrates the Unified Medical Language System . External links http www.diseasesdatabase.com Diseases Database Category Bioinformatics Category Medical literature website stub med org stub ar az Diseases Database bs Diseases Database ca Diseases Database cy Cronfa ddata o Afiechydon et Diseases Database es Diseases Database fa fr Diseases Database gl Diseases Database ko id Diseases Database jv Diseases Database no Diseases Database pl Diseases Database pt Diseases Database ru Diseases Database sr Diseases Database sv Diseases Database ta tr Hastal k Veri Taban uk Diseases Database ur vi Diseases Database zh ... more details
Orphan date February 2009 A database machine or back end processor is a computer or special hardware that stores and retrieves data from a database. It is specially designed for database access and is coupled to the main front end computer s by a high speed channel. This contrasts with a database server, which is a computer in a local area network that holds a database. The database machine is tightly coupled to the main CPU, whereas the database server is loosely coupled via the network. An example is the IBM System 38 . FOLDOC compu hardware stub Category History of computing ... more details
NMR database NMR nuclear magnetic resonance may refer to NMR spectra database , a collection of NMR spectra for a large number of compounds NMR database method , a strategy to identify the stereochemistry of certain chiral compounds dab ... more details
The Openedge Database is a relational database with some growing Object capabilities . It was formerly known as the Progress RDBMS. see also Progress Software Corporation OpenEdge Advanced Business Language database software stub Category Proprietary database management systems ... more details
Mergeto Database date January 2010 Notability date September 2009 A database administrator DBA is a person responsible for the design, implementation, maintenance and repair of an organization s database . They are also known by the titles Database Coordinator or Database Programmer , and is closely related to the Database Analyst , Database Modeler , Programmer Analyst , and Systems Manager . The role includes the development and design of database strategies, monitoring and improving database performance ... and implement security measures to safeguard the database. ref cite web url http www.acs.org.au ictcareers index.cfm?action show&conID 200707200948211895 title Database Administrator publisher ICT Careers Portal Australian Computer Society ref Employing organizations may require that a database administrator have a certification or degree for database systems for example, the Microsoft Certified Professional Microsoft Certified Database Administrator .28MCDBA.29 Microsoft Certified Database Administrator . Some organizations have a hierarchical level of database administrators, generally ... f27a4a19 254b 4fb6 a469 768d14d1fc81 40sessionmgr10&vid 4 title Database Administrator? DBA publisher ... skills br Willing to pursue education throughout your career br Database administrator s activities can be listed as below ref cite web url http www.developer.com db article.php 718491 What Is a Database Administrator.htm title What is a Database Administrator? DBA publisher Developer.com ref ref cite web url http www.developer.com db article.php 718491 What Is a Database Administrator.htm title What is a Database Administrator? DBA publisher Developer.com ref ref cite web url http www.businessdictionary.com definition Database Administrator DBA.html title Database Administrator DBA publisher BusinessDictionary.com ref Transferring Data Replicating Data Maintaining database and ensuring its availability to users Controlling privileges and permissions to database users Monitoring database ... more details
A lexical database is a lexical resource which has an associated software environment database which permits access to its contents. The database may be custom designed for the lexical information or a general purpose database into which lexical information has been entered. Information typically stored in a lexical databasedatabase includes lexical category and synonyms of words, as well as semantic relations between different words or sets of words. See also Machine readable dictionary WordNet External links http wordnet.princeton.edu The WordNet Home Page http lexicaldatabase.com Lexical Database Category Linguistics Category Translation databases database stub ar ... more details
Notability date October 2008 Unreferenced date October 2008 The LOLI List of LIsts Database is an international chemical regulatory database developed and maintained by ChemADVISOR, Inc. The LOLI database is one of the primary sources of information for the creation of material safety data sheet s and other hazard communication documents. The database was first created in 1986. Since then, the database has grown to include over 3000 separate lists from 93 countries. See also Chemical database External links http www.chemadvisor.com Products Lolidb.aspx ChemADVISOR, Inc. LOLI Database Category Occupational safety and health Category Chemical databases ... more details
A database refactoring is a simple change to a database schema that improves its design while retaining both its behavioral and informational semantics. A database refactoring is conceptually more difficult than a code refactoring code refactorings only need to maintain behavioral semantics while database refactorings also must maintain informational semantics. ref Scott Ambler and Pramod Sadalage 2006 . Refactoring databases Evolutionary database design . Addison Wesley. ISBN 978 0321293534 ref The process of database refactoring is the act of applying database refactorings to evolve an existing database schema database refactoring is a core practice of evolutionary database design . You refactor a database schema for one of two reasons to develop the schema in an evolutionary manner in parallel with the evolutionary design of the rest of your system or to fix design problems with an existing legacy database schema Database refactoring does not change the way data is interpreted or used and does not fix computer bug bug s or add new functionality. Every single refactoring to a database leaves the system in a working state, thus not causing maintenance lags, provided the meaningful data exists in the production environment. An example of database refactoring would be splitting an aggregate table into two different tables in the process of database normalization See also Test driven development Unit testing Refactoring Tools LiquiBase References reflist Refimprove date May 2009 External links http www.infoq.com presentations ambler database refactoring Database refactoring presentation at InfoQ.com by Scott W. Ambler http www.agiledata.org essays databaseRefactoring.html The Process of Database Refactoring by Scott W. Ambler http www.agiledata.org essays databaseRefactoringCatalog.html Catalog of Database Refactorings . by Scott W. Ambler. http www.databaserefactoring.com Database Refactoring Website by Pramod Sadalage Category Extreme Programming ... more details
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