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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
Define tuple variable? Tuple variables are used for comparing two tuples in the same relation. The tuple variables are explained in the from clause by way of the as clause.
What is recovery management component? Ensuring durability is the responsibility of a software component of the base system known as the recovery management component.
Define instance and schema? Instance: Collection of data kept in the data base at a particular moment is known as an Instance of the database. Schema: The o
Write an sql statement to find what is the percentage of home policies which are from the state of Arizona out of all Home policies by Policy Value.
Give the levels of data abstraction? There are three levels of Data Abstraction a) Physical level b) logical level c) view level
Designing the fields in the data base The following are the considerations one has to remain in mind while designing the fields in the data base. Coding, compression, en
Can you scan double-sided documents - and remove blank pages? Our software and imaging systems supports duplex scanning, at the same time scanning both sides of a page. Program
Describe integrity and security? a) Domain constraint b) Referential integrity A value that appears in one relation for a given set of attributes also appear fo
Define Outer join Outer join - If there are any type of values in the one table that do not have corresponding value(s) in the other, in an equi-join which will not be selected
Develop a database broker framework to implement a persistence mechanism for the domain objects involved in the use case dealt with in Question 2. a. Specify the attribute type
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