Infobox magazine title Communications of the ACM image file image size image caption editor Moshe Y. Vardi ... States based language English website http cacm.acm.org issn 0001 0782 Communications of the ACM CACM is the monthly Academic journal journal of the Association for Computing Machinery ACM . Established in 1957, CACM is sent to all ACM members, currently numbering about 80,000. The articles are intended for readers with backgrounds in all areas of computer science and information systems . The focus ... issues ACM also publishes a variety of more theoretical journals. CACM straddles the boundary of a science ... Communications of the ACM volume 1 issue 4 page 6 doi 10.1145 368796.368802 last1 Weiss first1 ... comptology Quentin Correll , ref cite journal author year title journal Communications of the ACM ... Communications of the ACM volume 2 issue 1 page 4 doi ref and datalogy Peter Naur . ref cite journal author year title journal Communications of the ACM volume 9 issue 7 page 485 doi ref C. A. R. Hoare ... Algorithm 64, and Find Algorithm 65 journal Communications of the ACM volume 4 issue 7 page 321 ... A Machine Program for Theorem Proving journal Communications of the ACM volume 5 issue 7 page 394 ... M. last4 Woodger first3 A. last3 Van Wijngaarden journal Communications of the ACM first2 J. H. volume ... of changing ACM s name, since the machinery in question is no longer the size of a house and is now ... to the ACM membership Why ACM? journal Communications of the ACM volume 8 issue 7 page 422 doi 10.1145 364995.364997 ref ref Cite journal author D.D. McCracken year 1976 title A letter from the ACM Vice President The ACM name change journal Communications of the ACM volume 19 issue 10 page 539 doi ... journal author R.L. Ashenhurst year 1986 title ACM forum journal Communications of the ACM volume 29 ... Simula An ALGOL based simulation language journal Communications of the ACM volume 9 issue 9 page ... Communications of the ACM volume 11 issue 3 page 148 doi ref The letter was reprinted in Jan 2008 ... more details
systems only, in particular ACM Multimedia Conference the first conference took place in Anaheim, California ... Language for Audio Visual Object Representation Other conferences on the same topic ACM International Conference on Multimedia Retrieval ICMR ACM International Conference on Multimedia Modeling MMM ACM Multimedia Systems Conference MMSYS IEEE International Conference Multimedia Expo ICME IEEE International ...Infobox Academic Conference history 1993 discipline multimedia abbreviation ACM MM publisher Association of Computing Machinery ACM SIGMM country International frequency annual ACM Multimedia ACM MM is the Association of Computing Machinery ACM s annual conference on multimedia , sponsored by the SIGMM ... journal title The World Comes to Bristol A Report from ACM Multimedia 98 author Simon Price journal ... 1 6 Anaheim, CA. ref cite book title Multimedia Systems author Ralf Steinmetz, Klara Nahrstedt year ... in May 1994 , SPIE Multimedia Computing and Networking MMCN , ACM Network and Operating System ... IWQoS , and European Workshop on Interactive Distributed Multimedia Systems and Telecommunication Services IDMS . ref USA ISBN 0 89791 596 8 ACM Multimedia workshops The http research.microsoft.com research ... speakers included Steve Mann and Gordon Bell . Open Source Competition Starting in 2004, ACM Multimedia ... ACM Multimedia Conference year 2008 ref 2007 http hop.inria.fr Programming Web Multimedia Applications with Hop . ref cite web url http mmc36.informatik.uni augsburg.de acmmm2007 title Program work ACM ... acmmm06 opensource.html title Open Source Competition work ACM Multimedia Conference year ... CLAM wins the 2006 ACM open source multimedia competition work Center for Research in Electronic Art Technology ref ref cite web url http www.mat.ucsb.edu node 79 title CLAM wins ACM MM Open Source ... Program work ACM Multimedia Conference year 2005 ref 2004 Two winners ref cite web url http www.acm.org ... on related topics ACM SIGGRAPH NIME International Computer Music Conference ICMC WIAMIS References ... more details
areas. The database research area has several notable dedicated academic journal s e.g., ACMTransactions on DatabaseSystems TODS, Data and Knowledge Engineering DKE, and more and annual Academic conference ... database management system DBMS . ref name Ullman Jeffrey Ullman and Jennifer widom 1997 First course in databasesystems , Prentice Hall Inc., Simon & Schuster, Page 1, ISBN 0 13 861337 0. ref A general ... data . It has evolved together with database management systems which enable the effective handling .... In the earliest databasesystems, efficiency was perhaps the primary concern, but it was already ... applications. The first generation of databasesystems were Navigational database navigational ... were made to build databasesystems with integrated hardware and software. The underlying philosophy ... databasesystems nowadays are software systems running on general purpose hardware, using general purpose ... of DatabaseSystems PODS , VLDB , IEEE ICDE, and more , as well as an active and quite heterogeneous ... a small subset of embedded database products is used in Real time computing real time embedded systems ... of as a database, albeit one spread across millions of independent computing systems. Web browsers ... using transaction databasetransactions . Essentially every major organization on earth uses ... that state. Data independence Main Data independence Data independence pertains to a database s Systems ... Database refimprove date December 2011 condense date November 2011 A database is an organized ... processes requiring this information for example, finding a hotel with vacancies . The term database is correctly applied to the data and their supporting data structures, and not to the database management system DBMS . The database data collection with DBMS is called a database system . The term database system implies that the data is managed to some level of quality measured in terms of accuracy .... Well known DBMSs include Oracle Database Oracle , IBM DB2 , Microsoft SQL Server , Microsoft Access ... more details
dusrm m 129.html Designation Systems US missiles Aviation lists DEFAULTSORT Agm 129 Acm Category ... Terrain Contour Matching TERCOM . detonation launch platform B 52 Stratofortress The AGM 129 ACM Advanced ... Systems . The AGM 129A is carried exclusively by the US Air Force s B 52 Stratofortress B 52H B ... would have difficulty penetrating future air defense systems. The AGM 86B relied on low altitude flight ... of the Beriev A 50 airborne early warning systems with look down radars reduced the likelihood that the low ... in 1987. US Congressman Les Aspin called the ACM a procurement disaster with the worst problems ... out funding for the ACM program in 1989. Manufacturing quality problems led the US Air Force to stop ... ACM procurement. The President determined that only 640 missiles were needed. The ACM program ... to be a Conventional weapons non nuclear version of the ACM, much as the nuclear AGM 86B led to the conventional ... http www.designation systems.net dusrm m 129.html title Raytheon General Dynamics AGM 129 ACM publisher ... 2,200 deployed nuclear weapons by 2012, with the ACM chosen because it has reliability issues and higher ..., Nebraska See also Portal United States Air Force commons AGM 129 ACM Aircontent related similar ... Missile Systems , Hajime Ozu, Shinkigensha, Tokyo, 2000 Japanese 2003 2004 Weapons File , United ... Air to surface missiles of the United States de AGM 129 ACM es AGM 129 ACM fr AGM 129 ACM it AGM 129A ACM nl AGM 129 ACM ja ACM ro AGM 129 ACM ru AGM 129 ACM ... more details
The ACM Portal is an online service of the Association for Computer Machinery . ref name portal http portal.acm.org ACM Portal ref Its core are two main sections ACM Digital Library ACM DL , and the Guide to Computing Literature . ref http www.libs.uga.edu research subject computer science The University of Gerogia Guide to Online Resources ref The ACM Digital Library is the full text collection of all articles published by the ACM in its articles, magazines and conference proceedings. The Guide is a bibliography in computing with over one million entries. ref name portal See also IEEE Xplore References reflist Category Association for Computing Machinery Category Digital library projects Category Online databases Category Bibliographic databases Category Bibliographic databases in computer science ... more details
ACM Queue ISSN 1542 7730 is a computer magazine published by the Association for Computing Machinery ACM . Stephen R. Bourne Steve Bourne helped found the magazine when he was President of the ACM and he is now Chair of the Advisory Board. The magazine is produced by computing professionals and is intended for computing professionals. It is available in print and electronic form for ACM members and other qualified computing professionals. External links http queue.acm.org Official website http liinwww.ira.uka.de bibliography Misc queue.html Bibliography compu mag stub Category Association for Computing Machinery publications Queue Category Computer magazines es ACM Queue ... more details
Infobox Company company name ATLANTIC ACM company logo company type foundation 1991 location Boston, Massachusetts key people Dr. Judy Reed Smith, Fedor Smith area served industry Telecommunications and information technology market research and benchmarking, management consulting products revenue operating income net income num employees parent subsid homepage footnotes ATLANTIC ACM is an independent research consultancy serving the telecommunications and information technology industries. Although the firm addresses all aspects of business strategy and publishes the telecommunications industry s sizing and market share studies and forecasts , ATLANTIC ACM is best known for its Excellence Awards, which are derived from its Carrier Report Card series. The firm is based in Boston , Massachusetts and has affiliates in more than 70 foreign markets. ref http www.atlantic acm.com index.php?option com content&view article&id 21&Itemid 9 ref History and Milestones ATLANTIC ACM was founded in 1991 by Dr. Judy Reed Smith, a Harvard educated strategist who tackled her first telecommunications industry project in 1987 ref http www.phoneplusmag.com articles profiles 6ch281112266175.html ref and worked for such consultancies as Gray Judson Howard offshoot of Arthur D. Little and Mercer Management Consulting. ref http www.prepaid press.com news detail.php?t paper&id 2530 ref The firm planted its flag in the competitive telecommunications industry by establishing many of the then young industry ... Association COMPTEL . ref http www.thefreelibrary.com ATLANTIC ACM CEO Appointed to ASCENT 27s Board of Directors 3B Dr. Judy... a095441824 ref In 2009, ATLANTIC ACM president Fedor Smith ... ref Benchmarking and ATLANTIC ACM Excellence Awards ATLANTIC ACM began its benchmarking research ... ACM s practice, it the area most associated with the firm because of ATLANTIC ACM Excellence Awards ... Atlantic Acm Category Companies based in Boston, Massachusetts ... more details
E. Denning, Secure statistical databases with random sample queries, ACMTransactions on DatabaseSystems TODS , Volume 5, Issue 3 September 1980 , Pages 291 315 doi 10.1145 319830.319834 Wiebren de Jonge, Compromising statistical databases responding to queries about means, ACMTransactions on DatabaseSystems, Volume 8, Issue 1 March 1983 , Pages 60 80 doi 10.1145 320128.320138 Dorothy E. Denning, Jan Schl rer, A fast procedure for finding a tracker in a statistical database, ACMTransactions on DatabaseSystems, Volume 5, Issue 1 March 1980 . Pages 88 102 Category Statistical databases ...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 multidimensional database multidimensional 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. ... 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 ... more details
Databases. ACMTransactions on DatabaseSystems , 12 3 , 325 349. ref ref name source2 Pottinger ... queue s, Database trigger trigger s, Data type type s, sequence s, materialized view s, Synonym database synonym s, database link s, Directory file systems directories , Java programming language ... database theory. In Proceedings of the 1982 ACM SIGMOD international conference on Management of data ...Mergefrom Schema object date March 2012 Image Mediawiki dbschema.svg thumb A depiction of MediaWiki database schema. A database schema pronounced skee ma , IPA en ski.m of a database system is its structure described in a formal language supported by the database management system DBMS and refers to the organization of data to create a blueprint of how a database will be constructed divided into database tables . The formal definition of database schema is a set of formulas sentences called integrity constraints imposed on a database. These integrity constraints ensure compatibility between parts of the schema. All constraints are expressible in the same language. A database can be considered a structure in realization of the database language . ref name source1 The states of a created conceptual schema are transformed into an explicit mapping, the database schema. This describes how real world entities are modeled in the database. br A database schema specifies, based on the database administrator s knowledge of possible applications, the facts that can enter the database, or those of interest to the possible end user s. ref name source3 The notion of a database schema plays the same ... to a database, which can be seen at any instant of time as a mathematical object . Thus a schema can ... specifically for a type of database, all expressed in the same database language. ref name source1 In a relational database , the schema defines the Table database tables , Field computer science fields , Relational model relationship s, View database view s, Index database index es, Software ... more details
Unreferenced date November 2009 Transactions demand , in economics economic theory , specifically Keynesian economics , is one of the determinants of supply and demand demand for money and Credit finance credit , the others being speculative demand and precautionary demand . Transactions demand is illustrated as a vertical line on the money demand graph. The demand of money is arisen form the absence of perfect snchronization of payments and receipts. The holding of money is to bridge the gap between payments and receipts. Transaction demand for money is due to the household motive to hold money for daily transaction and the business motive to facilitate the daily operation. The transactions demand for money is positively related with the amount of real income.It also depends on the timing of expenditures and the length of the pay period. The Baumol Tobin model focuses on the optimum number of transactions for a household. DEFAULTSORT Transactions Demand Category Keynesian economics Category Demand Econ theory stub ... more details
ACM Guide to Computing Literature is a database, published by the Association for Computing Machinery ACM , that categorizes and abstracts most computer science literature. It contains citations to all ACM publications, as well as literature from other publishers. The Guide was also published in print from 1977 until 1997. All of the citations included in the printed Guide from 1987 through 1997 are included in the online database citations from print issues of the Guide published prior to 1987 are not necessarily found in the online version. The Guide is not to be confused with the ACM Digital Library . The Digital Library provides complete texts of journals, magazines and conferences sponsored or published by ACM. See also Association for Computing Machinery ACM Digital Library ACM Computing Reviews External links http www.acm.org ACM official website http portal.acm.org guide.cfm ACM Guide to Computing Literature limited access for non subscribers http portal.acm.org dl.cfm ACM Digital Library limited access for non subscribers http www.reviews.com ACM Computing Reviews limited access for non subscribers Category Bibliographic databases in computer science Category Association for Computing Machinery publications Guide to Computing Literature Category Association for Computing Machinery Guide to Computing Literature compu mag stub database stub es ACM Guide to Computing Literature pt ACM Guide to Computing Literature ... more details
Infobox Journal title Perkin Transactions cover discipline Chemistry abbreviation Perkin Trans. 1 and Perkin Trans. 2 website http www.rsc.org Publishing Journals dt index.asp publisher Royal Society of Chemistry country United Kingdom history 1997 to 2002 ISSN Perkin Transactions is a scientific journal devoted to organic chemistry published from 1997 to 2002 by the Royal Society of Chemistry . It was split into Perkin Transactions I and Perkin Transactions II . The predecessor journals published by the Chemical Society before the merger of that Society with other Societies to form the Royal Society of Chemistry were the Journal of the Chemical Society , Perkin Transactions 1 and Journal of the Chemical Society, Perkin Transactions 2 1972 1996 . They were replaced by Organic and Biomolecular Chemistry . External links Royal Society of Chemistry s http www.rsc.org Publishing Journals P1 Index.asp Website for Perkin 1 Royal Society of Chemistry s http www.rsc.org Publishing Journals P2 Index.asp Website for Perkin 2 See also List of scientific journals in chemistry List of scientific journals chem journal stub Category Chemistry journals Category Royal Society of Chemistry academic journals Category English language journals ... more details
Use dmy dates date September 2011 Infobox journal title Dalton Transactions cover File CoverIssueDaltonTrans.jpg ..., Dalton Transactions Inorganic Chemistry 1972 2003 Journal of the Chemical Society A Inorganic, Physical ... Portal Chemistry Dalton Transactions is a peer review peer reviewed scientific journal publishing ... OpenScience index.asp Retrieved 2011 02 22 ref The editor in chief of Dalton Transactions is Jamie .... This ranks Dalton Transactions 7th out of 43 listed journals in the Chemistry, Inorganic & Nuclear ... journals Journal of the Chemical Society, Dalton Transactions covering inorganic and organometallic chemistry Faraday Transactions Journal of the Chemical Society, Faraday Transactions 1 Physical Chemistry in Condensed Phases and Faraday Transactions Journal of the Chemical Society, Faraday Transactions 2 Molecular and Chemical Physics . Journal of the Chemical Society, Dalton Transactions was then renamed in 2003 to Dalton Transactions . In January 2000, Dalton Transactions incorporated Acta ... Transactions was published as 12 issues a year from 1972, as submissions increased, the journal switched ... Dalton Transactions Developing for the Inorganic Community journal Dalton Trans. pages 15 17 publisher ... B516708F accessdate 2011 02 26 ref Volume renumbering In 2010, Dalton Transactions introduced a sequential ... year since the publication of Journal of the Chemical Society, Dalton Transactions . ref http www.rsc.org ... Transactions publishes articles on all aspects of the chemistry of Inorganic chemistry inorganic ... doi 10.1039 J19660001711 ref Article types Dalton Transactions publishes the following types ... published in Dalton Transactions . ref http www.rsc.org Publishing Journals guidelines AuthorGuidelines JournalPolicy Journals DT.asp Retrieved 2011 03 12 ref Abstracting and indexing Dalton Transactions ... Dalton Transactions work Chemical Abstracts Service Source Index CASSI Displaying Record for Publication ... Index Web of Science Scopus GeoRef Citations The five journals that cited Dalton Transactions ... more details
Comparable transactions is one of the conventional methods to value a company for sale. The main approach of the method is to look at similar or comparable transactions where the acquisition target has a similar business model and similar client base to the company being evaluated. This approach is fundamentally different from that of DCF valuation method, which calculates intrinsic value. Example For instance, Providence Equity Partners acquired Virtual Radiologic Corporation, which is an online clinic that provides radiologist analysis through a virtual network. It was sold for a price of 282 million and an enterprise Value of 242 million. To evaluate a similar unsold company, we would look at what are called the transaction multiples. One popular transaction multiple is EV EBITDA . For Virtual Radiologic Corporation, the EBITDA at the time of the transaction was 20 million, giving an EBITDA multiple of 12.1x. A similar unsold company, which has EBITDA at 10 Million could expect to be sold for 120 million. In some market segments, the companies do not have high EBITDA, and sometimes a multiple based on revenues EV sales is used instead. To get a more accurate valuation, one should look at the multiples of more than one similar deals that are relatively recent since multiples do change from year to year. References http www.tscpa.com publicinfo SBarticles art of valuations.aspx The Art of Valuations , by Carole Belmar, CPA http www.researchratings.com article.asp?id 598 Valuations based on comparable transactions by Research Ratings http www.mergers acquisitions.org glossary term 167 Comparable Transaction Analysis in the Glossary of mergers acquisitions.org DEFAULTSORT Mergers And Acquisitions Category Corporate finance Category Mergers and acquisitions ... more details
The ACM Computing Classification System is a subject classification system for computer science devised ... Classification in scope, aims and structure, being used by the various ACM journals to organise subjects .... Structure The ACM Computing Classification System is hierarchically structured in four levels three ... are listed as uncoded subject descriptors in these standard subcategories. Navbox name ACM Computing Classification System title ACM Computing Classification System image above The 1998 version of the ACM ... reliability . list3 concerns Computer organization computer systems organization . The subtopics ... communication networks , special purpose and application based systems, Performance tuning performance of systems , and Implementation computer system implementation . list4 is entitled Software . This section ... software . list8 pertains to information systems . It includes subtopics for models and principles, Databasedatabase management , information storage and Information retrieval retrieval , information systems applications, and information interfaces and presentation e.g., Human computer ... Humanities humanities , computer aided engineering , and computers in other systems. list11 has as its ... and information systems , the computing profession, and Personal computer personal computing . See ... of topics in its computer science subject areas but also allows papers to be classified using the ACM ... of the ACM location New York, NY, USA pages 111 112 publisher ACM title ACM s computing classification ... Bernard journal Computing Reviews location New York, NY, USA publisher ACM pages 1 5 title Computing ... a Computer Science Research Organization on the ACM Computing Classification System editor1 ... ACM Computing Classification System is the homepage of the system, including links to three complete ... 1998 acmccs98 1.2.3.xml XML version of the ACM Computing Classification System version 1998 The http arxiv.org corr home ACM Computing Research Repository uses a http arxiv.org corr subjectclasses classification ... more details
An Active Database is a database that includes an event driven architecture often in the form of Event Condition Action ECA rules which can respond to conditions both inside and outside the database. Possible uses include security monitoring, alerting, statistics gathering and authorization. Most modern relational databases include active database features in the form of Database trigger SQL Triggers . See also Event driven architecture References cite journal last Paton first Norman W coauthors D az, Oscar title Active databasesystems journal ACM Computing Surveys year 1999 volume 31 issue 1 pages 63 103 doi 10.1145 311531.311623 url http portal.acm.org citation.cfm?id 311623 accessdate 8 July 2010 publisher ACM location NY, USA issn 0360 0300 Use dmy dates date October 2010 DEFAULTSORT Active Database Category Types of databases Database stub ... more details
have other options available. Distributed transactionsDatabasesystems implement distributed transaction ... a database remain uncompleted, with unclear status. To provide isolation between programs accessing a database concurrently. If this isolation is not provided the programs outcome are possibly erroneous. A database transaction, by definition, must be Atomicity databasesystems atomic , Consistency databasesystems consistent , Isolation databasesystems isolated and Durability databasesystems durable ... other transactions, results must conform to existing constraints in the database, and transactions that complete successfully must get written to durable storage. Purpose Database s and other data stores ... transactions on the database are able to be rolled back if they are not completed properly e.g. due ... into the category of databases that support transactions. In a database system a transaction might ... using code START TRANSACTION code , autocommit will often also be reenabled. Some databasesystems ... service ensures that all parts of the transaction are applied to all relevant systems. As with database ...Refimprove date August 2010 A transaction comprises a unit of work performed within a database management system or similar system against a database, and treated in a coherent and reliable way independent of other transactions. Transactions in a database environment have two main purposes To provide reliable units of work that allow correct recovery from failures and keep a database consistent even ... that are atomic, consistent, isolated, and durable ACID . ref Database practitioners often refer to these properties of databasetransactions using the acronym ACID . Transactions provide an all or nothing proposition, stating that each work unit performed in a database must either complete ... transactions to maintain the integrity of data. A single transaction consists of one or more independent units of work, each reading and or writing information to a database or other data store. When ... more details
Refimprove date December 2009 Orphan date December 2009 A cooperative database is a type of database that holds information on customers and their transactions. Many companies will contribute information to a database in return for aggregate information on the customers other companies have provided. Such databases are used for promotional mailings, credit card fraud detection and fighting E mail spam . Alternatively, the term cooperative database can be used to describe databasesystems that incorporate techniques to aid users beyond returning direct answers. ref Wesley W. Chu Cooperative DatabaseSystems. Wiley Encyclopedia of Computer Science and Engineering, 2008. ref Such databases can, for example, give explanations as to why a query returns no or few results, detect and report some user misconception suggested by the query, provide justifications for returned answers, or relax query attributes to find close but non precise answers. The fundamental goal is to extend databases towards reflecting the cooperative principle , and in particular, to avoid misleading users by omission of pertinent, contextual detail. References Reflist DEFAULTSORT Cooperative Database Category Anti spam Category Types of databases ... more details
italictitle ACM Computing Reviews ISSN 1530 6585 is an academic journal that reviews computer science literature. It is published by the Association for Computing Machinery ACM . See also ACM Guide to Computing Literature ACM Computing Surveys External links http www.reviews.com ACM Computing Reviews limited access for non subscribers compu mag stub Category Association for Computing Machinery publications Computing Reviews Category Computer science journals Category Publications with year of establishment missing es ACM Computing Reviews pt ACM Computing Reviews ... more details
Normal Form for the Design of Relational Database Schemata. ACMTransactions on DatabaseSystems ... Dependencies and a New Normal Form for Relational Databases journal ACMTransactions on DatabaseSystems .... An Introduction to DatabaseSystems . Addison Wesley 1999 , p. 290 ref Most 3NF tables are free of insertion ... and Relational Database Operators . ACM SIGMOD International Conference on Management of Data, May 31 ... to DatabaseSystems 8th ed. . Addison Wesley Longman. ISBN 0 321 19784 4. Kent, W. 1983 http ...Technical date March 2012 Database normalization is the process of organizing the Field computer science fields and Table database table s of a relational database to minimize redundancy and dependency ... of a field can be made in just one table and then propagated through the rest of the database ... for Large Shared Data Banks journal Communications of the ACM volume 13 issue 6 month June year ... Model . Presented at Courant Computer Science Symposia Series 6, Data Base Systems , New York City ... Base Systems Courant Computer Science Symposia Series 6 . Prentice Hall, 1972. ref and Codd and Raymond ... CoddBCNF Codd, E. F. Recent Investigations into Relational Data Base Systems . IBM Research Report ... database table database table the computerized representation of a relation database relation is often ... form 4NF , and Fifth normal form 5NF but typically not Sixth normal form 6NF . A standard piece of database ... have somehow failed to meet requirements. Date, C.J. Database in Depth Relational Theory for Practitioners ... flawed. ref Codd, E.F. Chapter 23, Serious Flaws in SQL , in The Relational Model for Database ... of each of these objectives. Free the database of modification anomalies File Update anomaly.svg 280px ... is known as a deletion anomaly . Minimize redesign when extending the database structure When a fully normalized database structure is extended to allow it to accommodate new types of data, the pre existing aspects of the database structure can remain largely or entirely unchanged. As a result ... more details
Unreferenced date September 2009 A parallel database system seeks to improve performance through parallelization of various operations, such as loading data, building indexes and evaluating queries. Although data may be stored in a distributed fashion, the distribution is governed solely by performance considerations. Parallel databases improve processing and input output speeds by using multiple CPU s and disks in parallel. Centralized and client server databasesystems are not powerful enough to handle such applications. In parallel processing, many operations are performed simultaneously, as opposed to serial processing, in which the computational steps are performed sequentially. Parallel databases can be roughly divided into two groups, the first group of architecture is the multiprocessor architecture, the alternatives of which are the followings Shared memory In hardware Shared memory architecture , where multiple Central processing unit processors share the main memory space, as well as mass storage e.g. hard disk drive s . Shared disk architecture , where each node has its own main memory, but all nodes share mass storage, usually a storage area network . In practice, each node usually also has multiple processors. Shared nothing architecture , where each node has its own mass storage as well as main memory. The other architecture group is called hybrid architecture, which includes Non Uniform Memory Architecture NUMA , which involves the Non Uniform Memory Access . Cluster shared nothing shared disk SAN NAS , which is formed by a group of connected computers. References Communications of the ACM http portal.acm.org citation.cfm?id 129894 Parallel databasesystems the future of high performance databasesystems DEFAULTSORT Parallel Database Category Types of databases database stub de Paralleles Datenbanksystem ... more details
in the area are the ACM Symposium on Principles of DatabaseSystems PODS and the International Conference on Database Theory ICDT . References Citation last Abiteboul first Serge author link ... query Expressive power Database DEFAULTSORT Database Theory Category Database management systems Category Database theory lv Datu b u teorija tr Veritaban kuram zh ...Database theory encapsulates a broad range of topics related to the study and research of the theoretical realm of database s and database management system s. Theoretical aspects of data management include, among other areas, the foundations of query languages, computational complexity and expressive power of queries, finite model theory , database design theory, dependency theory database theory dependency theory , foundations of concurrency control and database recovery , deductive database s, temporal database temporal and spatial database s, real time database s, managing uncertain data and probabilistic database s, and Web data. Most research work has traditionally been based on the relational model , since this model is usually considered the simplest and most foundational model of interest. Corresponding results for other data models, such as object oriented or semi structured model s, or, more recently, graph data models and XML , are often derivable from those for the relational model. A central focus of database theory is on understanding the complexity and power of query languages and their connection to logic . Starting from relational algebra and first order logic which are equivalent by Codd s theorem and the insight that important queries such as graph reachability are not expressible in this language, more powerful language based on logic programming and fixpoint logic such as datalog were studied. Another focus was on the foundations of query optimization and data integration . Here most work studied conjunctive query conjunctive queries , which admit query ... more details
database without affecting other modules systems . Reliable transactions Due to replication of database ... Information Systems pp. 185 189 . New York, NY McGraw Hill Irwin ref Besides distributed database replication and fragmentation, there are many other distributed database design technologies. For example, local autonomy, synchronous and asynchronous distributed database technologies. These technologies ... among other things. Transactions are transparent each transaction must maintain database integrity ... to maintain multiple disparate systems, instead of one big one. Extra database design work must also ... 978 1 4419 8833 1 FS1037C FS1037C Elmasri and Navathe, Fundamentals of databasesystems 3rd edition ...refimprove date August 2010 Cleanup date June 2009 A distributed database is a database in which computer ... network network of interconnected computers. Collections of data e.g. in a database can be distributed across multiple physical locations. A distributed database can reside on network servers on the Internet ... . The replication and distribution of databases improves database performance at end user worksites. ref O Brien, J. & Marakas, G.M. 2008 Management Information Systems pp. 185 189 . New York, NY McGraw ... software that looks for changes in the distributive database. Once the changes have been identified .... It basically identifies one database as a master and then duplicates that database ... location has the same data. In the duplication process, changes to the master database only ... of the data to be stored in the database, and hence the price the business is willing to spend on ensuring data security, consistency and integrity. Architecture A database user accesses the distributed database through Local applications applications which do not require data from other sites. Global applications applications which do require data from other sites. A distributed database does not share main memory or disks. Important considerations Care with a distributed database must be taken ... more details
Encyclopedia
top
