Saturday, August 15, 2009
What is VLDB
The perception of what constitutes a VLDB continues to grow. A one terabyte database would normally be considered to be a VLDB
What is ETL
ETL is a short for Extract, Transform and Load. It is a data integration function that involves extracting the data from outside sources , transforming it into business needs and ultimately loading it into a datawarehouse
ETL is an abbreviation for "Extract, Transform and Load".This is the process of extracting data from their operational data sources or external data sources, transforming the data which includes cleansing, aggregation, summarization, integration, as well as basic transformation and loading the data into some form of the data warehouse.
E: Extraction of data from the homogeneous/heterogenous sources.
T: Transforming/modifying the source data by applying some transformations like Filter, Expression, Router, Joiner, Union (or) Lookup.
L: Loading the Transformed data into corresponding Target tables.
ETL is an abbreviation for "Extract, Transform and Load".This is the process of extracting data from their operational data sources or external data sources, transforming the data which includes cleansing, aggregation, summarization, integration, as well as basic transformation and loading the data into some form of the data warehouse.
E: Extraction of data from the homogeneous/heterogenous sources.
T: Transforming/modifying the source data by applying some transformations like Filter, Expression, Router, Joiner, Union (or) Lookup.
L: Loading the Transformed data into corresponding Target tables.
What is the Difference between OLTP and OLAP
OLTP
Current data
Short database transactions
Online update/insert/delete
Normalization is promoted
High volume transactions
Transaction recovery is necessary
OLAP
Current and historical data
Long database transactions
Batch update/insert/delete
Denormalization is promoted
Low volume transactions
Transaction recovery is not necessary
OLTP is nothing but OnLine Transaction Processing ,which contains a normalised tables and online data,which have frequent insert/updates/delete.
But OLAP(Online Analtical Programming) contains the history of OLTP data, which is, non-volatile ,acts as a Decisions Support System and is used for creating forecasting reports.
Index
OLTP : FEW
OLAP : MANY
JOINS
OLTP : MANY
OLAP : FEW
oltp:
1.current data only
2.insert,update,delete operations are possible
3.continous changing of data
4.1 year data is present
5.only one record is processed at a time
6.data is present in 2d format
olap:
1.current+historical data
2.used for reprting and analysis
3.non volatile in nature
4.5-30 yrs of data is stored
5.group of records processed at a time
6.data is present in muti dim format
Current data
Short database transactions
Online update/insert/delete
Normalization is promoted
High volume transactions
Transaction recovery is necessary
OLAP
Current and historical data
Long database transactions
Batch update/insert/delete
Denormalization is promoted
Low volume transactions
Transaction recovery is not necessary
OLTP is nothing but OnLine Transaction Processing ,which contains a normalised tables and online data,which have frequent insert/updates/delete.
But OLAP(Online Analtical Programming) contains the history of OLTP data, which is, non-volatile ,acts as a Decisions Support System and is used for creating forecasting reports.
Index
OLTP : FEW
OLAP : MANY
JOINS
OLTP : MANY
OLAP : FEW
oltp:
1.current data only
2.insert,update,delete operations are possible
3.continous changing of data
4.1 year data is present
5.only one record is processed at a time
6.data is present in 2d format
olap:
1.current+historical data
2.used for reprting and analysis
3.non volatile in nature
4.5-30 yrs of data is stored
5.group of records processed at a time
6.data is present in muti dim format
What is ER Diagram?
ER - Stands for entitity relationship diagrams. It is the first step in the design of data model which will later lead to a physical database design of possible a OLTP or OLAP database
The Entity-Relationship (ER) model was originally proposed by Peter in 1976 [Chen76] as a way to unify the network and relational database views.
Simply stated the ER model is a conceptual data model that views the real world as entities and relationships. A basic component of the model is the Entity-Relationship diagram which is used to visually represents data objects.
Since Chen wrote his paper the model has been extended and today it is commonly used for database design For the database designer, the utility of the ER model is:
it maps well to the relational model. The constructs used in the ER model can easily be transformed into relational tables.
it is simple and easy to understand with a minimum of training. Therefore, the model can be used by the database designer to communicate the design to the end user.
In addition, the model can be used as a design plan by the database developer to implement a data model in a specific database management software.
The Entity-Relationship (ER) model was originally proposed by Peter in 1976 [Chen76] as a way to unify the network and relational database views.
Simply stated the ER model is a conceptual data model that views the real world as entities and relationships. A basic component of the model is the Entity-Relationship diagram which is used to visually represents data objects.
Since Chen wrote his paper the model has been extended and today it is commonly used for database design For the database designer, the utility of the ER model is:
it maps well to the relational model. The constructs used in the ER model can easily be transformed into relational tables.
it is simple and easy to understand with a minimum of training. Therefore, the model can be used by the database designer to communicate the design to the end user.
In addition, the model can be used as a design plan by the database developer to implement a data model in a specific database management software.
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