3i Infotech Papers: Sample Questions 420 - 421 of 1245

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Question number: 420

» Basic CS » Data Structures

Essay Question▾

Describe in Detail

In RDBMS, what is the efficient data structure used in the internal storage representation.

Explanation

In RDBMS, B + tree structure is the efficient data structure used in the internal storage representation.

B + tree:

Understanding of B+ tree

Understanding of B + Tree

Understanding of B + tree

  • A “B + tree” is an n-array tree with a node, which consists of a large number of children per node.

  • Root is a leaf or a node containing more than two children- consists of a root internal nodes and leaves.

  • Same as a B tree, difference is that B + tree is an additional level added at bottom with leaves.

  • Primary value of the B + tree is in storing and maintaining the data.

  • Provides an efficient housing data structure format, which makes them simple in accessing and storing- Useful as database system index.

Question number: 421

» Database » MySQL

Essay Question▾

Describe in Detail

What are Armstrong rules? How do we say that they are complete and/or sound

Explanation

Define Armstrong rules.

Define Armstrong Rules.

Define Armstrong rules.

  • Armstrong’s Axioms is a set of rules.

  • Provides a simple technique for reasoning about functional dependencies.

  • Used to infer all the functional dependencies on a relational database.

    The well-known inference rules for FD

  • Reflexivity:

    • If A is a set of attributes and B is a subset of A, then A holds B.

  • Augmentation

    • If A hold B and C is a set of attributes, then AC holds BC.

    • It means that attribute in dependencies does not change the basic dependencies.

  • Transitivity

    • If A holds B and B holds C, then A holds C.

    • If then

    • A hold means that A functionally determines B.

  • Union

    • If A holds B and A holds C, then A holds BC.

    • If and

  • Pseudo Transitivity

    • If A holds B and BC holds D, then AC holds D.

    • If

  • First three are known as Amstrong Rules.

  • They are sound because it is enough if a set of FDs satisfy these three. They are called complete because using these three rules we can generate the rest all inference rules