Databases and Database Systems Essay Example | Topics and Well Written Essays - 1250 words

Databases and Database Systems - Essay Example A database management system is a collection of programs that enables the user to create and maintain a database. In the Database Management System (DBMS), sharing a database allows multiple users and programs to access the database concurrently. Other important functions provided by the DBMS include protecting the database and maintaining it over a long period of time. Protection includes both system protections against hardware or software malfunction (or Crashes) and security protection against unauthorized or malicious access. A database typically has many uses, each of which may require a different perspective or view of the database. A multi-user DBMS, as its name implies, must allow multiple users to access the database at some time. This is essential if data for multiple applications to be integrated and maintained in a single database. The DBMS must include concurrency control software to ensure that several users trying to update the same data do so in a controlled manner s o that the result of updates is correct. These types of applications are generally called online transaction processing applications. A fundamental role of multi-users DBMS software is to ensure that concurrent transactions operate correctly. The concept of a transaction has become central to many database applications. A transaction is an executing program or process that includes one or more database accesses, such as reading or updating database records. Each transaction is supposed to execute logically correct database access is executed in its entirety without interference from other transaction. The DBMS must enforce several transaction properties. The isolation property ensures that each transaction appears to execute in isolation from other transactions, even though a hundred of the transaction may be executing concurrently. When multiple users share a large database, it is likely that most users with not be authorized to access all the information in the database. In additi on, some users may be permitted only to retrieve data whereas others are allowed both to retrieve and update. Hence, the type of access operation must also be controlled. A DBMS should provide a security and authorization subsystem. As we know, multiple users can access databases and use computer systems simultaneously because of the concept of multiprogramming. In this concurrent process, execution of processes is actually interleaved and most of the theory concerning concurrency control in a database is developed in terms of interleaved concurrency. In a multi-users DBMS, the stored data items are the primary resources that may be accessed concurrently by interactive users or application programs, which are constantly retrieving information and modifying the database. In this process, concurrency control is very much needed to avoid a certain type of problems. Concurrency control and recovery mechanisms are mainly concerned with the database access commands in a transaction. Trans action submitted by the various users may execute concurrently and may access and update the same database items. If this concurrent execution is uncontrolled it may lead to problems such as an inconsistent database, the lost update problem, and temporary update problem. Transaction failure may occur due to integer overflow or division by zero or erroneous parameter  values or logical programming errors.

British Ethnic Legacy in Africa Essay Example | Topics and Well Written Essays - 1000 words

British Ethnic Legacy in Africa - Essay Example This paper contends that problem of tribalism and negative ethnicity that has dominated the African social cultural political and economic spheres giving rise to intense rivalry, divisions and frequently civil strife is predominantly a legacy of British colonialism. Using their superior economic and political position, they created deep-seated divisions that destroyed the social- political harmony in Africa since even after they left the class inequalities and negative feelings that some communities had towards others who collaborated with colonialist remained to fuel future conflict (Blanton, David & Brian 474). Nigeria exemplifies the divisive nature of ethically motivated politics; therefore, British colonialist divided the country with the intention of making it easier to control in the typical divide and rule policy capitalizing on the preexisting ethnic and religion differences (Amadife & Warhola 533). The British were gradually withdrawing from the country and with them the co ntrol they had exerted over the different groups; however, the disunity that served the British so well in marginalizing and effectively making it impossible for the tribe to unify against them became a cause for civil conflict. The long run effects are evident in the civil war of 1967- 1970 when the nations was almost split asunder as communities fought form behind the artificial boarders the British cleaved into their country. Even today, many insecurity problems facing the country are due to ethic conflicts which can be traced back to the British Imperialist’s actions. In addition, another example can be seen in the infamous Rwanda genocide of 1990, as aforementioned, elevating certain communities over others to effectively practice indirect rule was a tactic the British widely employed, however the aftermath of the divisions which usually ran deep has often been catastrophic in posterity (Blanton, David & Brian 478). While it would appear that the conflict was a primarily matter of tribal issues with no connection to the retrospective colonial past, critical examination of the events leading up to the period implies otherwise. Since their takeover of the country in the late 19th century, the British had taken advantage of existing divisions between the two tribes and by sideling the Hutu and elevating the Tutsis who the deemed as more civilized than the Hutus (Wa Wamwere 142). Decades after independence, the Hutu used the fact that the Tutsis had been loyal to the British in retrospect to massacre them and strengthen their position as legitimate leaders of the country, the Exiled Tutsis came back to try to salvage the situation and this resulted in a full scale war to end the aftermath and the British who had sowed the seeds of the bloody divisions were nowhere to quell the situation. Opponents of this papers claim will likely claim that not all African colonies degenerated in violence and ethnic politics, to this end, they may cite Tanzania, Liberi a and several other states that remained peaceful. Therefore, according to them, accusing the British of being responsible for Africa’s present and past problems is unreasonable and the situation would probably be much worse had it not been for their intervention in the first place. In addition, attributing the problems of Africa to