Data Warehousing Basics

Foreign keys of facts tables are primary keys of Dimension tables. It is clear that fact table contains columns which are primary key to other table that itself make normal form table.

The Fact table is central table in Star schema, Fact table is kept Normalized because its very bigger and so we should avoid redundant data in it. Thats why we make different dimensions there by makin...

A source table has a single column, we not transfer this column to dimension table, directly to connected to the fact table ,this fact table called the de-generated dimensional table

Best example is "Invoice Number","bill number","PO Number", these all are degenerated dimensions in the Transaction Tables, they can be maintained in the fact table itself instead of  crating seperate dimensions for this.

I think, we don't need separate space for Data Warehouse and Data Mart. Data Warehouse is a collection of Data Marts. Data Mart is a particular line of business..

Why so.....Is there any advantage creating the DWH after creating the Datamarts...?

what is the use of Vice versa...?

A dimension is considered to be a rapidly changing dimension if one or more of its attributes changes frequently in many rows. For a rapidly changing dimension, the dimension table can grow very large from the application of numerous Type 2 changes.

A rapidly changing dimension is a result of poor decisions during the requirements analysis and  data modeling stages of the Data Warehousing project. If the data in the dimension table is changing a lot, it is a hint that the design should be revisited.

1. Oracle Warehouse Builder (OWB) 11gR1 Oracle 2. Data Services XI 3.2 SAP Business Objects 3. IBM Information Server (Datastage) 9.1 IBM 4. SAS Data Integration Studio 4.21 SAS Institute 5. Pow...

ODI is the future of all ETL tools..because its E-LT not ETL.

Surrogate key is a numeric or integer value in a table to identify each row uniquely. Primary key and surrogate key are same but surrogate key is a system generated value has a define incremental valu...

Surrogate key and primary key both are same, but point of application is different. Primary key is part of transactional system but surrogate key is part of analytical system. Surrogate key is used...

cross reference table used to describe many-2-many relation between tables. aggregate fact table - when granularity of fact data not required fact can be grouped over dimensions, measures will be af...

Incremental Loading:Its also called retrospective data load.In this data being loaded on a regular inerval,and only new data is moved.eg in ur data warehouse ur loading "Transactional Data" ...

If a table contains the values, which are neither dimension nor measures is called degenerate dimensions.Ex : invoice id, empno

Degenerated Dimension is achieved through a gradual modeling approach following Dimensional Modeling standards. Let's take example of a Star Schema representing Sales Invoices. The FACT would have...

OLTP: 1.insert/update 2.thousands of users 3.size 1gb to 4gb 4.day to day operations 5.transaction of data,detailed data 6.application oriented OLAP: 1.read-query 2.hundreads of people(only d organiz...

OLTP 1) Original source of data2) Normalized 3) Quries are simple ...

Could you please give me one real time example How we do data cleansing.....

It is nothing but purifying data , the extract process always exposes the data qulaity issues that have been bured within the operational source system. Since the data qulaity significantly impacts da...

OLTP: It stores current data.

ODS: It stores recent data

OLTP: It is real time transaction. so all transaction comes in oltp, which are being perform at current time. ex- if we go to any showroom and buy anything then showroom owner creates our database and...

service requirement means establishing the connection between client and server...right? well if it is then i can guide you that how to connect a client machine to server via repository. once the ser...

Could you please detail the question? Loading history is nothing to do with number of workflows. Might be you got confused between initial load and incremental load. A single workflow can be used for...

one work flow.....

I think the answer the best suits this question is as below: Entity - Relationship Modelling:- Removes data redundancy. Ensures data consistency. Expresses relationship between the entities....

ER ModelProcess : NormalizationJoin : More ( n-1)Detail DataSize: MB to GBData : Current Datauser's : More than 1000Data: Volatile.Dimensional ModelingProcess: DenormalizationJoin: LessData: Summarize...

Pushdown Optimization is a new feature introduced from Informatica 8. To increase session performance, the integration service pushes transformation logic to the source or target database. Based on t...

Pushdown Optimization will push the source query with transformation logic

Business key is a primary key in the operational system. Surrogate key is a system generated primary key. In Dimensions and Facts we use Surrogate keys as Primary keys. Please refer my answer for the...

Business Key is nothing but a natural key.Surrogate key is a system generator just like sequence in oracle.Basically we come across this in slowly changing dimensions type-II category.

The dictionary meaning of Homogeneous is Uniform and Heterogeneous is Mixed. For example if a mapping is using only Oracle sources or Flat files or DB2 or XML or any other then they are called Homogen...

Hey Opbang Ur statement "Datawarehousing is not just having a single data warehouse", with datawarehousing it is understood that business decision can be taken and lots of information and analysis rep...

dataware house is a container to  store the historical data

where as dataware hosuning is a process or technique  to analyze tha data in the ware house

We have tried QTP from HP and RFT from IBM. Both can launch SQL and you can script around doing the result compares but it is not easy. we now use QuerySurge.

No Tool testing in done in DWH, only manual testing is done.

star schema defined as,A fact table is surrounded my many multiple dimension tables.
(it means all dimension tables directly maintains relationship with the fact tables in this schema)

star schema (also called star-join schema, data cube, or multi-dimensional schema) is the simplest style of data warehouse schema. The star schema consists of one or more fact tables referencing any n...