Physical Design
Overview * Purpose
Translate the logical description of data into the technical specifications of storing and retrieving data.
* Goal
Create a design for storing data that will provide adequate performance and ensure database integrity, security and recoverability. Basically, the primary goal of physical database design is data processing efficiency.
* Physical Design Process
Inputs such as normalized relations and estimation of their volume; definitions of each attributes; expectations and requirements for response time, data security, back-up, retention and recovery; and integrity; and description of the DBMS technology used to implement the database leads to critical decisions that will affect the integrity and performance of the system such as: * Choosing the storage format called data-type for each attribute from the logical data model. The format is chosen to minimize storage space and to maximize data integrity. * Grouping attributes from the logical data model into physical records. * Arranging similarly structured records in secondary memory (primary hard disks) so that individual and groups of records (called file organizations) can be stored, retrieved and updated rapidly. Consideration may also be given to protect data and recovering data after errors are found. * Selecting structures (called indexes and database architectures) for storing and connecting files to make retrieval of related data more efficient. * Preparing strategies for handling queries against the database that will optimize performance and take advantage of the file organizations and indexes that the users have specified. Efficient database structures will be of benefit only if queries and the management systems that handle those queries are tuned intelligently to use those structures.
Data Volume and Usage Analysis
The physical design of data base requires certain information that should have been collected and produced during initial phases of system
Translate the logical description of data into the technical specifications of storing and retrieving data.
* Goal
Create a design for storing data that will provide adequate performance and ensure database integrity, security and recoverability. Basically, the primary goal of physical database design is data processing efficiency.
* Physical Design Process
Inputs such as normalized relations and estimation of their volume; definitions of each attributes; expectations and requirements for response time, data security, back-up, retention and recovery; and integrity; and description of the DBMS technology used to implement the database leads to critical decisions that will affect the integrity and performance of the system such as: * Choosing the storage format called data-type for each attribute from the logical data model. The format is chosen to minimize storage space and to maximize data integrity. * Grouping attributes from the logical data model into physical records. * Arranging similarly structured records in secondary memory (primary hard disks) so that individual and groups of records (called file organizations) can be stored, retrieved and updated rapidly. Consideration may also be given to protect data and recovering data after errors are found. * Selecting structures (called indexes and database architectures) for storing and connecting files to make retrieval of related data more efficient. * Preparing strategies for handling queries against the database that will optimize performance and take advantage of the file organizations and indexes that the users have specified. Efficient database structures will be of benefit only if queries and the management systems that handle those queries are tuned intelligently to use those structures.
Data Volume and Usage Analysis
The physical design of data base requires certain information that should have been collected and produced during initial phases of system