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Question
Describe query optimization and the modes that an optimizer can operate in.Answer
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Related questions
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A dependency of one nonprime attribute on another nonprime attribute is a partial dependency.
a. True
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A determinant is any attribute whose value determines other values within a column.
a. True
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It is possible for a table in 2NF to exhibit transitive dependency, where the primary key may rely on one or more nonprime attributes to functionally determine other nonprime attributes.
a. True
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A table is in 2NF if it is in 1NF, and it includes no partial dependencies.
a. True
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Converting a database format from 1NF to 2NF is a complex process.
a. True
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In the context of partial dependencies, data redundancies occur because every row entry requires duplication of data.
a. True
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Repeating groups must be eliminated by ensuring that each row defines a single entity.
a. True
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A table is in BCNF if every determinant in the table is a foreign key.
a. True
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Normalization is a process that is used for changing attributes to entities.
a. True
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From a data modeling point of view, ___________--data refer to data whose values change over time and for which one must keep a history of the data changes.
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The " __________________" characteristic of a primary key states that the primary key must uniquely identify each entity instance, must be able to guarantee unique values, and must not contain nulls.a. unique valuesb. nonintelligentc. preferably single-attributed. security-complaint
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A primary key's main function is to uniquely identify a(n)_______________ within a table.a. attributeb. entity instance or rowc. entity subtyped. natural key or identifier
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An entity cluster is formed by combining multiple interrelated entities into_______________ .a. a single abstract entity objectb. multiple abstract entity objectsc. a single entity objectd. multiple entity objects
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______________is the bottom-up process of identifying a higher-level, more generic entity supertype from lower-level entity subtypes.a. Specializationb. Generalizationc. Normalizationd. Total completeness
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Overlapping subtypes are subtypes that contain_______--- subsets of the supertype entity set.a. nullb. exclusivec. solitaryd. nonunique
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Nonoverlapping subtypes are subtypes that contain a(n)________ subset of the supertype entity set.a. entityb. subtypesc. uniqued. nonunique
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Which of the following is a specialization hierarchy overlapping constraint scenario in case of partial completeness?
a. Subtype sets are unique.
b. Supertype has optional subtypes.
c. Subtype discriminators cannot be null.
d. Subtype does not have a supertype.
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At the implementation level, the supertype and its subtype(s) depicted in a specialization hierarchy maintain a(n)__________ relationship.a. self-referencingb. 1:1c. 1:Md. M:N
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What components should an implementation-ready data model contain?
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In_________________________ , a threepronged symbol represents the "many" side of the relationship.
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Each row in a relation is called a(n)_______________ .
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A(n) ________________is a brief, precise, and unambiguous description of a policy, procedure, or principle within a specific organization.
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The relational data model was developed in the_______ . a. 1960s b. 1970sc. 1980s d. 1990s
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MySQL is an example of the____________ .a. hierarchical model b. file system data modelc. relational data model d. XML data model
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Students and classes have a ____________relationship.a. one-to-one b. one-to-manyc. many-to-one d. many-to-many
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A(n)__________ is a restriction placed on the data.a. attribute b. entityc. relationship d. constraint
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A(n)________ 's main function is to help one understand the complexities of the realworld environment.a. node b. entityc. model d. database
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The hierarchical model is software-independent.a. Trueb. False