Physical design is the process of determining how data will be stored, accessed, and managed at the physical level in a Database Management System (DBMS).
- It focuses on optimizing database performance, ensuring security, and efficiently utilizing storage resources.
Key Considerations in Physical File and Database Design:
1.) Storage Structures:
Storage structures determine how data is physically organized on disk, influencing data retrieval speed and storage efficiency.
Types of File Structures:
Sequential Files:
- Data is stored in a sequential order, making it efficient for batch processing but slow for random access.
- Used in applications requiring large-scale reporting.
Indexed Files:
- An index is created to quickly locate records without scanning the entire file.
- Common in search-heavy applications like customer databases.
Hashed Files:
- A hash function is used to directly map data to a location, providing fast retrieval for specific queries.
- Best suited for key-value lookups (e.g., user authentication).
2.) Indexing:
Indexing enhances query performance by allowing rapid data retrieval without scanning the entire table.
Types of Indexes:
- Primary Index: Built on a table’s primary key for fast lookup.
- Secondary Index: Created on non-primary key attributes to speed up searches.
- Clustered Index: Stores data rows in the same order as the index.
- Non-clustered Index: Keeps data separate from the index, requiring additional lookup steps.
Indexing Strategy:
- Use indexes on frequently queried columns.
- Avoid excessive indexing to prevent slow write operations.
3.) Partitioning:
Partitioning divides large tables into smaller, more manageable parts to improve query performance and scalability.
Types of Partitioning:
- Horizontal Partitioning: Splits records across multiple tables based on row values (e.g., storing data by region).
- Vertical Partitioning: Stores specific columns separately to optimize access to frequently used attributes.
- Range Partitioning: Divides data based on a predefined range (e.g., yearly sales data stored separately).
Benefits:
- Enhances query performance by reducing search space.
- Improves data management and scalability.
4.) Security:
Security in physical design ensures data protection against unauthorized access, breaches, and corruption.
Key Security Measures:
- Access Controls: Implementing role-based access control (RBAC) to restrict unauthorized data access.
- Encryption: Encrypting sensitive data at rest and in transit for protection.
- Backups and Recovery: Regular backups to prevent data loss in case of failures.
- Auditing and Logging: Tracking user activities to detect anomalies and security threats.
