Question 1 Which is not a reason why data integration across multiple organizations is harder than integration within an organization? SQL can be implemented differently in different databases, which creates a need to reconcile those differences. Efficient execution of queries over multiple systems is challenging. Query processing in distributed databases is challenging. Data from different sources tend to be structured differently.
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Question 1Which is not a reason why data integration across multiple organizations is harder than integration within an organization?
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SQL can be implemented differently in different databases, which creates a need to reconcile those differences.
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Efficient execution of queries over multiple systems is challenging.
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Query processing in distributed databases is challenging.
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Data from different sources tend to be structured differently.
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Question 2
Which statement accurately distinguishes the roles of the wrapper and source description in a mediated schema?
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The wrapper requests and parses data from the sources, while the source description converts data from the source schemas and values into the global representation.
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The source description requests and parses data from the sources, while the wrapper converts data from the source schemas and values into the global representation.
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The wrapper abstracts source data, while the source description requests and parses data from the sources.
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The source description abstracts source data, while the wrapper requests and parses data from the sources.
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Question 3
Which of the following statements is true about data warehouse integration systems and virtual data integration systems?
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A virtual data integration system uses ETL, or extract-transform-load, tool pipelines that periodically extract data from the sources and load them an application.
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Both data integration architectures use a mediated schema.
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A data warehouse integration system leaves data in the sources and accesses them as needed at query time.
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In the warehousing approach, the user poses queries in terms of the warehouse schema.
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Question 4
______ considerably simplifies the task of expressing complex queries because they can be written in smaller fragments and combined appropriately.
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Query unfolding
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Composability
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A datalog program
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Integrity constraints
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Question 5
What is specified by a relational schema?
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The number of arguments in a query
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Limits of the possible states of the
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The set of attributes in the table and a data type for each attribute
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The contents of a database
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Question 6
Which is an example of an unstructured query?
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SQL query over an XML database
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XQuery query
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SQL query over a relational database
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A list of keywords
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Question 7
Which defines the Global-and-Local-as-View (GLAV) schema mapping?
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Expressions include a query over the data sources on the left-hand side and a query on the mediated schema on the right-hand side
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Focuses on describing each data source as precisely as possible and independently of any other sources
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Defines the mediated schema as a set of views over the data sources
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Derived from data dependency constraints and developed for the specification and analysis of integrity constraints in databases
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Question 8
Which describes the affine gap measure?
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Computed by assigning a score to each alignment between the two input strings and choosing the score of the best alignment
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An extension of the Needleman-Wunsch measure that handles longer gaps more gracefully
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Computes the minimal cost of transforming string x to string y
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Designed to find matching substrings by introducing two key changes to the Needleman-Wunsch measure
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Question 9
Which describes the Monge-Elkan similarity measure?
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Effective in matching names, since names are often spelled in different ways that sound the same
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Retrieves only the strings in Y whose size makes them match candidates
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Limits the set of candidate matches by deriving an upper bound on the size of the overlap between a pair of strings
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Effective for domains in which more control is needed over the similarity measure
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Question 10
Which is not a common integrity constraint in a database?
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Functional dependencies
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Key
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Foreign key
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Null value
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Which of the following statements is true about data warehouse integration systems and virtual data integration systems?
by Bartleby ExpertWhich statement accurately distinguishes the roles of the wrapper and source description in a mediated schema? A) The wrapper requests and parses data from the sources, while the source description converts data from the source schemas and values into the global representation. B) The source description requests and parses data from the sources, while the wrapper converts data from the source schemas and values into the global representation. C) The wrapper abstracts source data, whiye the source description requests and parses data from the sources. D) The source description abstracts source data, while the wrapper requests and parses data from the sources
by Bartleby Expert
