What Is Meant By Denormalization In SQL?


3 Answers

ayesha sana Profile
ayesha sana answered
De-normalization is an application tool in SQL server model. There are three methods for de-normalization:.

• Entity inheritance
• Role expansion
• Lookup entities.

Entity Inheritance

This method for the de-normalization should be implemented when one entity is named as another entity. This will do with the help of inheritance. Inheritance means parent child relations of entity. This will be do with making the foreign key and candidate key. This is also in notice that creation of model creates a band of relationship and if you select the inheritance this property should be automatically deleted.

Role Expansion

This type of de-normalization should be created when it is surety that one entity has the relationship to another entity or it is a part of another entity. In this storage reason is removed. It is used with the help of Expand inline function. It use the shared schema is used in from of table.

Lookup Entities

This type of de-normalization is used when entity depend on the lookup table. It is work with the help of Is Look up property. This property applies on the entity. These three will give authority to user to create a genuine and tempting report model .This model is navigation experience for the customer.
Zeshan Hayder Profile
Zeshan Hayder answered
Demoralization is a technique to move from higher to lower normal forms of database modeling in order to speed up database access. Demoralization process is applied for deriving a physical data model from a logical form. In logical data base design we group things logically related through same primary key. In physical database design fields are grouped, as they are stored physically and accessed by DBMS. In general it may decompose one logical relation into separate physical records, combine some or do both. There is a valid reason for demoralization that is to enhance the performance. However, there are several indicators, which will help to identify systems, and tables, which are potential demoralization candidates.
Which are:
• Many critical queries and reports exist which rely upon data from more than one table. Often times these requests need to be processed in a non-line environment.
• Repeating groups exist which need to be processed in a group instead of individually.
• Many calculations need to be applied to one or many columns before queries can be successfully answered.
• Tables need to be accessed in different ways by different users during the same timeframe.
• Certain columns are queried a large percentage of the time. Consider 60% or greater to be a cautionary number flagging demoralization as an option.
We should be aware that each new RDBMS release usually bring enhanced performance and improved access options that may reduce the need for demoralization. However, most of the popular RDBMS products on occasion will require demoralized data structures. There are many different types of demoralized tables, which can resolve the performance problems caused when accessing fully normalized data. Demoralization must balance the need for good system response time with the need to maintain data, while avoiding the various anomalies or problems associated with demoralized table structures. Demoralization goes hand-in-hand with the detailed analysis of critical transactions through view analysis. View analysis must include the specification of primary and secondary access paths for tables that comprise end-user views of the database. A fully normalized database schema can fail to provide adequate system response time due to excessive table join operations.
Anonymous Profile
Anonymous answered
Advantages and disadvantages of denormalization?

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