What is denormalization, and why can it be desirable? Provide an example. Give e

Question

What is denormalization, and why can it be desirable? Provide an example.

Give examples of binary 1:N relationships, other than those in the textbook, for (a) an optional-to-optional relationship, (b) an optional-to-mandatory relationship, (c) a mandatory-to-optional relationship, and (d) a mandatory-to-mandatory relationship. Illustrate your answer using IE Crow’s Foot E-R diagrams.

Both Questions need to be atleast 200 words and if possible with cited sources. Thank you.

Explanation / Answer

http://en.wikipedia.org/wiki/Denormalization Denormalization is when redundant data is added to the database to optimize the read. Denormalisation techniques are often used to improve the scalability of Web applications. For example you are looking for a single record in a data set Denormalizing your tables inorder to optimize your programs Big O notation will allow your program to search faster, but write slower. #2Binary Relationships. //is this supposed to be Multiplicity Relationships with ER diagrams or Big O notation? (a) 1:N or One to many (N) is like a for loop like in C++ for (unsigned i=0; i> i >>endl;} This 1:N realationship is = to 1:10 because the code executes 10 times as is set by the loop. (b) Optional to mandatory When something optional in ER diagram directly relates to a mandatory part of the ER diagram (c)Mandatory to optional The opposite of b. This is where a mandatory Use Case has optional use cases. (d)mandatory to mandatory Where there is a direct and necessary relation between two Use cases. The sources are cited in the wiki article, for your reference.

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