What was the predecessor of DBMS? What is the structure of GAUM (generalized update access method)? Explain the evolvement of DBMS from file-based storage systems to relational database systems.... [Show More]


By CPA Guru 2 weeks ago

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The predecessor of DBMS was the File Management System. In the file-based version of storing data and information, data was maintained in a flat file. The Generalized Update Access Method (GUAM) made use of a hierarchical database structure. The Structure included a root node with one or more children related to the parent node. In the structure of GUAM, a parent node may have many children nodes, but a child may have only one parent node. As such, data was organized like a tree structure which enabled the repeating of information through the establishment of many parent/child relationships. The implemented structure was mainly used in the first mainframe database management systems which allowed high application maintenance and fast data-access path. File-based is the predecessor of the database where data was maintained in a flat file. Files were preceded by punched cards. However, flat files did not have any significant advantages; rather they held several disadvantages. First, flat files or file-based method required extensive programming in third-generation programming languages. Secondly, there were high levels of duplicated data which led to a waste of memory space. Thirdly, the file-based system lacked robust security features making it vulnerable to unauthorized access to data. Fourth, there were high maintenance costs such as controlling access and ensuring data consistency. File-Bases systems were followed by hierarchical databases which allowed a tree-like structure where there was a root node, followed by parent nodes and child nodes. The structure allowed a parent node to have many children nodes while a child node could only have one parent node. Advantages of the hierarchical database model were efficient searching, enabled data independence, integrity and security of data and less data redundancy. However, it had some significant drawbacks which included complex implementation of the database and lack of structural independence. Hierarchical Database Model was followed by Network Data Model in which files were related as owners and members. In the network data model, each member file had the ability to have more than one owner. It had three unique database components which include sub-schema, network schema and data management language which was low level and procedural. Advantages of the network data model included easy access to data, enabling data integrity and independence and the increased ability to handle more relationships as compared to its predecessor. However, it also contained drawbacks which included system complexity and difficulty in designing and implementing and lack of structural independence. After the era of the network data model came that of relational databases. Relational databases defined the actions of retrieving, storing and creating data in a manner that will make it logically consistent. Relational databases were followed by object-oriented databases which supported the creation and modelling of data as objects. Object-oriented databases are known for their large storage capacity and high access speed. However, their architecture was not deemed appropriate for web applications.

By Professor Henry 2 weeks ago . . .   helpful (10)    Marked as unhelpful (8)


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