3i Infotech Placement: Sample Questions 42 - 43 of 1245

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Question 42

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Describe in Detail

Essay▾

What is difference between process and thread?

Explanation

Table of Difference between Process and Thread
ProcessThread
Heavy weightLight weight
Has its own memory space.Use memory of the process they belong to
Inter process communication is slow as processes have different memory address.Inter thread communication is fast as threads of the same process share the same memory address.
Context switching between the process is more expensive.Context switching between threads of the same process is less expensive.
Processes don՚t share the memory with other process- consider privacy and securityThreads share the memory with other threads of the same process- consider privacy and security

Question 43

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Write in Short

Short Answer▾

Why can a “group by” or “order by” clause be expensive to process?

Explanation

  • GROUP BY, ORDER BY is executed by the Oracle engine. At the end, this leads to overhead, because whole data has to be rearranged again.
  • Group by: Combines all the similar rows and displays only the distinct data. Combining and displaying distinct data is an overhead.
  • Order by: Sorts the data either in ascending order or in descending order. Sorting the data is an overhead.
  • Processing of “group by” or “order by” clause requires creation of Temporary tables to process the results of the query, depending on the size of the result set can prove to be expensive.

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