Q1 : What Are The Different Types Of Data Warehousing?
A : Types of data warehousing are:
1. Enterprise Data warehousing
2. ODS (Operational Data Store)
3. Data Mart
Q2 : What Are The Steps To Build The Data Warehouse?
A : Gathering business requirements>>Identifying Sources>>Identifying Facts>>Defining Dimensions>>Define Attributes>>Redefine Dimensions / Attributes>>Organize Attribute Hierarchy>>Define Relationship>>Assign Unique Identifiers.
Q3 : What Are The Methodologies Of Data Warehousing?
A : Every company has methodology of their own. However, to name a few SDLC Methodology, AIM methodology is standardly used.
Q4 : What Is Data Warehousing Hierarchy?
A : Hierarchies are logical structures that use ordered levels as a means of organizing data. A hierarchy can be used to define data aggregation. For example, in a time dimension, a hierarchy might aggregate data from the month level to the quarter level to the year level. A hierarchy can also be used to define a navigational drill path and to establish a family structure. Within a hierarchy, each level is logically connected to the levels above and below it. Data values at lower levels aggregate into the data values at higher levels. A dimension can be composed of more than one hierarchy. For example, in the product dimension, there might be two hierarchies–one for product categories and one for product suppliers. Dimension hierarchies also group levels from general to granular. Query tools use hierarchies to enable you to drill down into your data to view different levels of granularity. This is one of the key benefits of a data warehouse. When designing hierarchies, you must consider the relationships in business structures. Hierarchies impose a family structure on dimension values. For a particular level value, a value at the next higher level is its parent, and values at the next lower level are its children. These familial relationships enable analysts to access data quickly.
Q5 : What Is Loop In Data Warehousing?
A : In DWH loops may exist between the tables. If loops exist, then query generation will take more time, because more than one path is available. It creates ambiguity also. Loops can be avoided by creating aliases of the table or by context.
Example: 4 Tables – Customer, Product, Time, Cost forming a closed loop. Create alias for the cost to avoid loop.
Q6 : What Is The Difference Between A Data Warehouse And A Data Mart?
A : A data mart is a subject-oriented database which supports the business needs of individual departments within the enterprise. It is a subset of the enterprise data warehouse. It is also known as high-performance query structures.
Q7 : What Is Real-Time Data-warehousing?
A : Data warehousing captures business activity data. Real-time data warehousing captures business activity data as it occurs. As soon as the business activity is complete and there is data about it, the completed activity data flows into the data warehouse and becomes available instantly.
Q8 : What Is The Difference Between Dependent Data Warehouse And Independent Data Warehouse?
Dependent departments are those, which depend on a data ware to for their data.Independent department are those, which get their data directly from the operational data sources in the organization.
Q9 : What Is Data Warehouse Architecture?
Data warehousing is the repository of integrated information data will be extracted from the heterogeneous sources. Data warehousing architecture contains the different; sources like oracle, flat files and ERP then after it have the staging area and Data warehousing, after that,it has the different Data marts then it have the reports and it also have the ODS – Operation Data Store. This complete architecture is called the Data warehousing Architecture.
Q10: What Is Data Analysis? Where It Will Be Used?
A : Data analysis: consider that you are running a business and u store the data of that; in some form say in register or in a comp and at the year-end, you won’t know the profit or loss then it called data analysis. Data analysis used: then u want to know which product was sold the highest and if the business is running in a loss then finding, where we went wrong we do analysis.
Q11 : How Can We Run The Graph? What Is The Procedure For That? How Can We Schedule The Graph In Unix?
A : If you want to run the graph through GDE then after saving the graph just press F5 button of your keyboard, it will run automatically. If you want to run through the shell script then you have to fire the command at your UNIX box.
Q12 : What Is Difference Between Drill & Scope Of Analysis?
A : Drilling can be done in drill down, up, through, and across; scope is the overall view of the drill exercise.
Q13 : What Are Data Modeling And Data Mining? Where It Will Be Used?
A : Data modeling is the process of designing a data base model. In this data model, data will be stored in two types of table fact table and dimension table.
Fact table contains the transaction data and dimension table contains the master data. Data mining is the process of finding the hidden trends is called the data mining.
Q14 : After The Generation Of A Report To Whom We Have To Deploy Or What We Do After The Completion Of A Report?
A : The generated report will be sent to the concerned business users through web or LAN.
Q15 : Where The Data Cube Technology Is Used?
A : A multi-dimensional structure called the data cube. A data abstraction allows one to view aggregated data from a number of perspectives. Conceptually, the cube consists of a core or base cuboids, surrounded by a collection of sub-cubes/cuboids that represent the aggregation of the base cuboids along one or more dimensions. We refer to the dimension to be aggregated as the measure attribute, while the remaining dimensions are known as the feature attributes.
Q16 : Which Technology Should Be Used For Interactive Data Querying Across Multiple Dimensions For A Decision Making For A Dw?
A : MOLAP
Q17 : What Is Critical Column?
A : Let us take one ex: Suppose ‘XYZ’ is customer in Bangalore, he was residing in the city from the last 5 years, in the period of 5 years he has made purchases worth of 3 lacs. Now, he moved to ‘HYD’. When you update the ‘XYZ’ city to ‘HYD’ in your Warehouse, all the purchases by him will show in city ‘HYD’ only. This makes warehouse inconsistent. Here CITY is the Critical Column. The solution is used Surrogate Key.
Q18 : What Is Rollback Segment?
A : A Database contains one or more Rollback Segments to temporarily store “undo” information.
Q19 : What Is Virtual Data Warehousing?
A : A virtual or point-to-point data warehousing strategy means that end-users are allowed to get at operational databases directly using whatever tools are enabled to the “data access network”.
Q20 : What Is A Table Space?
A : A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.
Q21 : What Is A Private Synonyms?
A : A Private Synonyms can be accessed only by the owner.
Q22: What Is An Extent?
A : An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.
Q23 : What Is An Integrity Constrains?
A : An integrity constraint is a declarative way to define a business rule for a column of a table.
Q24 : What Are The Different Types Of Segments?
A : Data Segment,
Index Segment,
Rollback Segment
and
Temporary Segment.
Q25 : What Is An Index Segment?
A : Each Index has an Index segment that stores all of its data.