https://ir.unisa.ac.za/handle/10500/23877 2026-05-09T04:05:34Z https://ir.unisa.ac.za/handle/10500/24106 Database consistency under UNIX Viktor, HL; Rennhackkamp, MH A recovery technique, to facilitate the recovery from system failures should ensure a consistent database state at all times. The UNIX write system call uses a delayed-write policy. Data blocks are kept in a buffer cache and are later asynchronously written to disk. If a system failure occurs, logically complete transactions may be lost and the database may contain incorrect old data values. If a physical write was being executed when the failure occurred, the database will be inconsistent, since an update in place policy is used when writing to disk. Differential files can provide database consistency efficiently. 1991-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/24104 Automatic vectorization Tidwell, LD; Schach, Stephen R. It is becoming increasingly difficult for researchers with little or no formal computer science background to make effective use of supercomputers and other vector machines in their own fields of research. Automatic vectorization tools have been put forward as a possible solution to this problem. A description is given of experiences in utilizing an automatic tool to vectorize a program that models the frequency of lethal autosomal recessive genes. The vectorization was performed in order to run the program on a Cray Y-MP supercomputer. Drawbacks of current automatic vectorization tools are discussed, and approaches that could be used in the future to allow users of all levels of sophistication to utilize the full potential of supercomputers are suggested. 1991-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/24101 A causal analysis of job turnover among systems analysts Smith, DC; Hansen, AL; Oosthuizen, NC Staff Shortages in the Information Systems industry are a continuing problem. Job turnover of IS staff contributes to this shortage and is particularly high in South Africa. This high turnover is often attributed to inadequate remuneration. A study was conducted to determine the reasons why Systems Analysts leave their jobs. The results demonstrate that these individuals consider career growth and job content more important than salary. As these factors can be controlled by IS managers, certain actions are proposed to reduce the high turnover. 1991-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/24098 The universal relation as a database interface Philips, M.J.; Berman, Sonia The universal relation is a way of overcoming users' prime database access difficulty, namely navigation through database structures. As a result there is reduced user involvement with the underlying logical database structure. The universal relation is an imaginary relation that contains all the data in the database. Data element roles and 'flavours weak universal relations, and cycles in database structures are important related issues. Practical universal relation implementations include the computational approach, where the universal relation is generated; the use of multiple predefined views, and the window generation method. The latter has been most popular, largely due to the demands made on hardware by the processing of user views. 1991-01-01T00:00:00Z