Data Warehousing Questions

Q:

Define "Correlated Subqueries" ?

Answer

In a SQL Database, a 'correlated subquery' is a kind of sub query yet connected subquery is dependent on another query for a value that is returned. In case of execution, the sub query is executed first and afterwards the correlated query will be executed.

Report Error

View answer Workspace Report Error Discuss

6 1919
Q:

What is the difference between agglomerative and divisive Hierarchical Clustering?

Answer

- Agglomerative Hierarchical clustering method allows the clusters to be read from bottom to top and it follows this approach so that the program always reads from the sub-component first then moves to the parent. Whereas, divisive uses top-bottom approach in which the parent is visited first then the child. 


- Agglomerative hierarchical method consists of objects in which each object creates its own clusters and these clusters are grouped together to create a large cluster. It defines a process of merging that carries on till all the single clusters are merged together into a complete big cluster that will consists of all the objects of child clusters. Whereas, in divisive the parent cluster is divided into smaller cluster and it keeps on dividing till each cluster has a single object to represent.

Report Error

View answer Workspace Report Error Discuss

6 20519
Q:

State the difference between View and Materialized View ?

Answer

The main differenc between View and Materialized View states that -


1. View means it stores the SQL statement in the database and let you use it as a table. Everytime you access the view, the SQL statement executes.


2. Materialized view means it stores the results of the SQL in table form in the database. SQL statement only executes once and after that everytime you run the query, the stored result set is used. Advantage include quick query results.

Report Error

View answer Workspace Report Error Discuss

6 2984
Q:

What does BUS Schema means ?

Answer

BUS Schema is composed of a master suite of confirmed dimension and standardized definition if facts.

Report Error

View answer Workspace Report Error Discuss

6 2559
Q:

Define what is a Fact, Dimension and Measure ?

Answer

Fact is key performance indicator to analyze the business.From the additive values, which are used to analyse the business by using report generation. Dimension is used to analyze the fact, are the non-additive ( text format) values, Which are used to drill down reports.Without dimension there is no meaning for fact. Measure is the quantity of data we create to process.

Report Error

View answer Workspace Report Error Discuss

5 2276
Q:

What are the components of DataStage?

Answer

Datastage has two components


-Client Components – Designer, Director, Manager and Administrator


-Server Components – Server, Repository and Plug-ins.

Report Error

View answer Workspace Report Error Discuss

2 3820
Q:

What is the purpose of cluster analysis in Data Warehousing?

Answer

Cluster analysis is used to define the object without giving the class label. It analyzes all the data that is present in the data warehouse and compare the cluster with the cluster that is already running. It performs the task of assigning some set of objects into the groups are also known as clusters. It is used to perform the data mining job using the technique like statistical data analysis. It includes all the information and knowledge around many fields like machine learning, pattern recognition, image analysis and bio-informatics. Cluster analysis performs the iterative process of knowledge discovery and includes trials and failures. It is used with the pre-processing and other parameters as a result to achieve the properties that are desired to be used.

Report Error

View answer Workspace Report Error Discuss

1 4642
Q:

What is DataStage?

Answer

- A tool for designing Extraction, Transformation and Loading


- An ideal tool for data integration projects system migrations


- Importing, extracting and creating metadata are within these jobs


- Data stage allows scheduling, monitoring and running the jobs 


- Allows to administer the development and execution in a single environment


 

Report Error

View answer Workspace Report Error Discuss

1 3761