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Physical Sciences and Mathematics Commons™
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Full-Text Articles in Physical Sciences and Mathematics
An Experimental Study Into The Effect Of Varying The Join Selectivity Factor On The Performance Of Join Methods In Relational Databases, Ada Mallet
Theses : Honours
Relational database systems use join queries to retrieve data from two relations. Several join methods can be used to execute these queries. This study investigated the effect of varying join selectivity factors on the performance of the join methods. Experiments using the ORACLE environment were set up to measure the performance of three join methods: nested loop join, sort merge join and hash join. The performance was measured in terms of total elapsed time, CPU time and the number of I/O reads. The study found that the hash join performs better than the nested loop and the sort merge under …
User Response And Organisational Fit For Information Systems In Earth Observation, Jeff Kingwell
User Response And Organisational Fit For Information Systems In Earth Observation, Jeff Kingwell
Theses: Doctorates and Masters
A group of seventy six scientists and data managers in the Australian research agency CSIRO were surveyed to establish their needs and preferences in relation to information systems for Earth observation data. After study of available alternatives, three prototype Earth observation information management systems were installed and the user response was evaluated through interview of fifteen of the group. The prototypes consisted of web-based client servers which permitted users to interrogate databases of Earth observation datasets; to search for information about sensor or satellite performance, and to retrieve data and information products. The chosen systems were CILS, the CEOS (Committee …