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Define the Query optimisation
The query parser commonly generates a standard initial tree to correspond to an SQL query, with no doing any optimization. Such type of a canonical query tree denotes a relational algebra expression that is extremely inefficient if executed directly. A query commonly has many possible execution strategies, and the process of choosing a appropriate one for processing a query is termed as query optimization. The major guidelines that are applied throughout query optimization are:
a. Combine a cascade of selections
b. Combine a cascade of projections
c. Commute selection and projection
d. Commuting selection with join / cartesian product Commuting projection with join or cartesian product
e. Commute projection with set operations
f. Commute selection with set operations
Explain the differences between structured data and unstructured data. Structured data are facts concerning objects and events. The most significant structured data are numeric
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Define the Traditional System Analysis and Design Traditional System Analysis and Design (SAD) have three basic life cycle models. A typical software lifecycle consists of the
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Define Boyce codd normal form A relation schema R is in BCNF with respect to a set F of functional dependencies if, for all functional dependencies in F + of the form.α ->β.
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