3i Infotech Papers: Sample Questions 383 - 385 of 1245

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Question number: 383

» Database » MySQL

Essay Question▾

Describe in Detail

What are the different phases of transaction?

Explanation

Understanding of 3 phase of transaction.

Understanding of 3 Phase of Transaction.

Understanding of 3 phase of transaction.

Basically, 3 phase of transaction:

  • Analysis phase

  • Redo phase

  • Undo phase

Analysis phase:

  • Analysis phase is to find the best LSN starting from which rolling forward can be done during redo phase.

Redo:

  • Redo is the phase during which the changes caused by active transactions are hardened onto Data files.

Undo:

  • Undo is the phase where in, rolling back of the active transactions for consistency, takes place.

Question number: 384

» Operating System » Unix

Short Answer Question▾

Write in Short

How would you kill a process?

Explanation

  • To kill a process first find the process identifier number or PID, then pass the PID to the kill command.

  • In Unix, a process may be running in the background, foreground, or in a suspended state.

  • The OS shell will not return the prompt to the end-user until the current executing process finishes.

  • To kill a process a signal can also be sent via keystroke.

Question number: 385

» Operating System » Unix

Essay Question▾

Describe in Detail

What Happens when you execute a command?

Explanation

  • When command is given then unix forks the shell creating a new process which executes the command using “exec”.

  • For example when command “ls” in given in the shell:

    fork ();

    exec (ls);

  • Results are returned when the child process dies.

  • To execute a command shell will search the following regions

    • Physical memory

      • Alias

      • Functions

    • HDD

      • Builtin commands

      • Path

      • Execute permission

      • System calls FORK_EXEC_EXIT

  • When command is found it is executed with given info.