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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
Strong entity set and weak entity set? Strong entity set and weak entity set: A strong entity set has a primary key. All tuples in the set are distinguishable through that key.
Benefits of using heuristics
A use case diagram giving a pictorial overview of user requirements and brief use case descriptions. As the case study contains only an outline of a business scenario, you will als
Different stages of DDLC ?
Ask questApollo Hospitals (AH) is a popular medical service provider in Oman. AH wants to automate its business functions into an information system. The proposed information syst
Can your organization scan large format documents? Yes, large format scanning used for such entities as city plans and blueprints is available. We selected scanners with the ab
Increased parallelism : Since the replicated date has several copies a query can be distributed or can be answered from the smallest loaded site. Also, with more replicas you have
what would go in order patient#, patient name, patien address, surgeon#, surgeon name, surgery date, surgery type, drug admin
Discuss the count function? The COUNT function used returns the number of tuples or values fixed in a query. The count function comprises two types of syntax: (1) COUNT (*)
An entity set that does not have sufficient attributes to form a primary key is called? An entity set that doesn't have sufficient attribute to form a primary key is known as w
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