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Saturday, September 18, 2010
Monday, September 6, 2010
Hai Technocrats,
Now we will see Star and Snowflakes Schema.
Before going to the data models(Star and Snowflakes) let we discuss the dimension and fact tables.
Dimension Table:
- Dimension Table is nothing but a general table. It doesn’t have any special. It contains a description of each and every attribute(column).
- Dimension tables are usually large with number of columns but contains less number of rows.
- Dimension table is defined by its single primary key and it is used to join it to the fact table.
Fact Table:
- Fact table is a primary table in a dimensional model where the numerical, measurements are stored. Simply say Fact table contains Primary key, foreign key and Numerical values, nothing more than that.
- The most useful facts in a Fact table are numeric and additive.
- A Star Schema is a database design which contains a centrally located Fact table surrounded by dimension table.
- In the above Figure CUSTOMER, DATE, PRODUCT, VENDOR are the Dimension tables and ORDER is the Fact Table.
Snowflake Schema:
- In a Snowflake Schema a denormalized dimension table is split into one or more dimensional tables which results in partially normalized and fully normalized dimension.
- This schema is used to split the dimension into multiple, if the dimensions has too many columns in it. This helps to reduce the size of the dimension table.
In next posting let we see few simple what is BRIDGE Table and CONFORMED Dimension Table.
Sunday, September 5, 2010
happy Teachers Day To All Our Gate Faculty
Friday, September 3, 2010
Hai Technocrats,
Today let we go into subject of OBIEE. Now let we see the components of OBIEE
In OBIEE we have many components. Let we see few things
- Admin Tool
- Answers
- Dash Boards
- Delivers
- Services
- Catalog Manager
- BI Publisher or XML Publisher
- DAC (Data Warehouse Application Console)
- Disconnected Analytics
Now we see what are all those
1. Admin Tool:
Admin Tool is nothing but Administration Tool. It is the interface to create and manage repository and the logical schema.
Repository - The database repository keeps a local copy of database field definitions
Admin Tool contain 3 layers
· Physical Layer
· Business Model and Mapping Layer
· Presentation Layer
Physical Layer:
In physical Layer what we will do in this is
- Importing Meta Data
- Configuring Connection Pool
- Creating Alias Tables
- Creating Physical Joins
Business Model and Mapping (BMM) Layer:
In BMM Layer what we will do in this is
- We will develop all business logics(means Aggregate functions and some queries and also thing) in it.
- We create Hierarchical Dimensions, Aggregations, Level Based Measures
- Working with calculation wizard
- Creating calculation wizard
Presentation Layer:
In Presentation Layer what we will do in this is
- What every we place in the presentation layer all those things will be visible in Presentation services
- We can build here some security settings.
2. Answers:
- Development of Reports
- Development of Filters
- Development of Prompts
- Development of charts
- Development of Pivot tables
- Development of Tickers
- Development of column selectors
- Development of view selectors
3. Dash Boards
Dash Boards are the standard and interface for the majority of users
It allows multiple reports to be displayed in a tabbed interface
4. Delivers
The main things in the Delivers is IBOT
IBOT is a Intelligent Bursting Output Tool. It is an utility available in OBIEE and also in Siebel analytics which is used for Reports scheduling as well as alerts sent to the required recipients on different web accessible/communication devices
5. Services
We have few services
- BI Server
- Presentation Server
- Scheduler Server
If the services want to work means OC4J
The remaining Catalog Manager, BI publisher, DAC, Disconnected Analytics will be explained later on because all those are real time.
From next parts I will discuss each components in detail with UI.
Small assignment for you people who are following this posting, for reading next article try to go through Dimension table and Fact Tables.
Don’t sit like a Rock
Work hard like clock.
Wednesday, September 1, 2010
Hai Technocrats,
Today i wan say about Database used by OBI. Generally we have two types of database
- OLTP
- OLAP
OLTP Database: OLTP means Online Transaction Processing. This type of database will change frequently. Generally this type of database is used by Office Assistants/Clerks in a Business Organisation. Data in this type of database is Volatile, means changing frequentl
For example, take Student address in college database, if the student changes his/her address. In college database the new address is update but the old address will not exist. This type of database is called as OLTP database.
OLAP Database: OLAP means Online Analytical Processing. This type of database will not change, data will exist permanently. Generally this type of database is used by Business Manager for reports in a Business Organization. Because they will analyze the business for future development based on the past data. Actually OLAP Database is called as DATA WAREHOUSE.
OLAP Database is formed based on OLTP database. The abouve Figure roughly show you how the OLAP database will be populate.
But actually the above is not possible means inserting all OLTP data into data warehouse. So we use ETL Tool, through that we will insert all OLTP data into OLAP database or Data Warehouse.
ETL – Extract, Transform and Load.
ETL tools are Informatica, ODI, and Data Stage etc.
Ok we may get doubt why I am say all this. Ya, me also thought the same when am learning. But this is very important, our OBI reporting tool will connect to OLAP database. I already mention that reporting tool is for generating report with that Business people know the status.
In market we have so many number of Reports tools(OBI, COGONS etc). Almost all reporting tools will work with OLAP Database only.
If you start from DOWN, destination is TOP…
If you start from TOP, destination is DOWN.
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