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DBMS Query Processing MCQs: This section contains multiple-choice questions and answers on Query Processing in DBMS.
Submitted by Anushree Goswami, on May 13, 2022
1. Query ___ is the activity performed in extracting data from the database.
- Result
- Inhibition
- System
- Processing
Answer: D) Processing
Explanation:
Query Processing is the activity performed in extracting data from the database.
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2. Data is ___ from the database using various steps in query processing.
- Extracted
- Added
- Fetched
- Deleted
Answer: C) Fetched
Explanation:
Data is fetched from the database using various steps in query processing.
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3. How many steps are involved in fetching the data from the database in query processing?
- 1
- 2
- 3
- 4
Answer: C) 3
Explanation:
There are 3 steps involved in fetching the data from the database in query processing.
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4. What is/are the step(s) involved in fetching the data from the database in query processing?
- Parsing and translation
- Optimization
- Evaluation
- All of the above
Answer: D) All of the above
Explanation:
The steps involved in fetching the data from the database in query processing are -
- Parsing and translation
- Optimization
- Evaluation
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5. Initial queries from users are translated into a ____ database language such as SQL.
- Low-level
- Medium-level
- High-level
- None
Answer: C) High-level
Explanation:
Initial queries from users are translated into a high-level database language such as SQL.
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6. The queries are translated into ___ expressions at the level of the file system, which are used there as well.
- Virtual
- Real
- Physical
- None
Answer: C) Physical
Explanation:
The queries are translated into physical expressions at the level of the file system, which are used there as well.
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7. As soon as the queries are translated, they are evaluated and various ___ transformations are performed.
- Query-realizing
- Query-optimizing
- Query-deoptimizing
- Query-deletion
Answer: B) Query-optimizing
Explanation:
As soon as the queries are translated, they are evaluated and various query-optimizing transformations are performed.
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8. Whenever a computer system processes a query, it ___ first convert it into a language humans can comprehend.
- Need not to
- Must
- Can
- Maybe
Answer: C) Can
Explanation:
Whenever a computer system processes a query, it must first convert it into a language humans can comprehend.
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9. Query languages such as SQL are best suited for humans, however, it is not best suited for the ____ of queries to a system.
- Temptation
- Processing
- Transmission
- None
Answer: C) Transmission
Explanation:
Query languages such as SQL are best suited for humans, however, it is not best suited for the transmission of queries to a system.
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10. An ___ representation of a query is best suited to relational algebra.
- External
- Internal
- Both A and B
- None of the above
Answer: B) Internal
Explanation:
An internal representation of a query is best suited to relational algebra.
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11. Similar to a query parser, ___ is important in query processing.
- Transmission
- Translation
- Transfusion
- Transcreation
Answer: B) Translation
Explanation:
Similar to a query parser, translation is important in query processing.
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12. A user executes a query which the ___ in the system uses to generate the internal form of the query. In addition to checking the syntax of the query, the ____ verifies the name of the relation in the database, then the tuple, then the attribute value.
- Parser
- Translation
- Optimization
- Evaluation
Answer: A) Parser
Explanation:
A user executes a query which the parser in the system uses to generate the internal form of the query. In addition to checking the syntax of the query, the parser verifies the name of the relation in the database, then the tuple, then the attribute value.
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13. An '_____' is a tree of the query that the parser creates.
- Parse-tree
- Query-tree
- Tree
- None
Answer: A) Parse-tree
Explanation:
An 'parse-tree' is a tree of the query that the parser creates.
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14. To evaluate the translated ___ expression, it must be annotated with the instructions used to specify and evaluate each operation along with the translation.
- Analytical algebra
- Relational algebra
- Both A and B
- None of the above
Answer: B) Relational algebra
Explanation:
To evaluate the translated relational algebra expression, it must be annotated with the instructions used to specify and evaluate each operation along with the translation.
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15. The system must create a query ____ plan before it can fully evaluate a query.
- Optimization
- Parser
- Translation
- Evaluation
Answer: D) Evaluation
Explanation:
The system must create a query evaluation plan before it can fully evaluate a query.
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16. Depending on the assessment plan, annotations can be added to specify the algorithm to be used for the particular ____.
- Index
- Operation
- Both A and B
- None of the above
Answer: C) Both A and B
Explanation:
Depending on the assessment plan, annotations can be added to specify the algorithm to be used for the particular index or operation.
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17. Evaluation _____ are a special kind of relational algebra with annotations.
- Primitives
- Optimization
- Advancement
- None
Answer: A) Primitives
Explanation:
Evaluation Primitives are a special kind of relational algebra with annotations.
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18. In the primitives for ____, all instructions necessary for an operation's ____ are contained.
- Parser
- Translation
- Evaluation
- Optimization
Answer: C) Evaluation
Explanation:
In the primitives for evaluation, all instructions necessary for an operation's evaluation are contained.
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19. ____ evaluation plans describe the underlying primitive operations that are used to evaluate a query.
- Query
- Data
- Log
- Array
Answer: A) Query
Explanation:
Query evaluation plans describe the underlying primitive operations that are used to evaluate a query.
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20. Query evaluation plans are also known as query ____ plans.
- Execution
- Enumeration
- Eternal
- None
Answer: A) Execution
Explanation:
Query execution plans are also known as query evaluation plans.
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21. To generate the output of a query, a ___ is responsible.
- Query execution engine
- Query execution motor
- Query execution train
- None
Answer: A) Query execution engine
Explanation:
To generate the output of a query, a query execution engine is responsible.
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22. In the end, it makes the user's query ____ after taking the query execution plan, executing it, and finally making the ____.
- Input
- Output
- Query
- Log
Answer: B) Output
Explanation:
In the end, it makes the user's query output after taking the query execution plan, executing it, and finally making the output.
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23. What is TRUE about Query Optimization?
- The cost of evaluating a query can vary depending on its type.
- The evaluation plan is built by the system, so the user need not focus on writing their query efficiently.
- An efficient query evaluation plan is generated by a database system, which minimizes its costs.
- All of the above
Answer: D) All of the above
Explanation:
In case of Query Optimization -
- The cost of evaluating a query can vary depending on its type.
- The evaluation plan is built by the system, so the user need not focus on writing their query efficiently.
- An efficient query evaluation plan is generated by a database system, which minimizes its costs.
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24. An efficient query evaluation plan is generated by a database system, which minimizes its costs and it is known as -
- Query evaluation
- Query optimization
- Query parser
- Query translation
Answer: B) Query optimization
Explanation:
An efficient query evaluation plan is generated by a database system, which minimizes its costs and it is known as Query optimization.
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25. It is mandatory that the query ___ has an estimate of each operation's cost when optimizing a query.
- Evaluator
- Optimizer
- Parser
- Translator
Answer: B) Optimizer
Explanation:
It is mandatory that the query optimizer has an estimate of each operation's cost when optimizing a query.
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26. Costs of memory allocation, execution, and so on are factors that impact the overall ___ cost.
- Execution
- Allocation
- Operation
- None
Answer: C) Operation
Explanation:
Costs of memory allocation, execution, and so on are factors that impact the overall operation cost.
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27. When a query is evaluated, the system produces an output based on the ____ plan selected.
- Query plan
- Evaluation plan
- System plan
- Output plan
Answer: B) Evaluation plan
Explanation:
When a query is evaluated, the system produces an output based on the evaluation plan selected.
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