Best practices
Basics
Designing an effective database structure is crucial for performance, scalability, and maintainability. Here are some common best practices, particularly in the context of Oracle databases, with examples:
- Normalization - to organize data to reduce redundancy and improve data integrity.
Example:
Instead of storing customer information repeatedly in an Orders table, create a separate Customers table and reference it using a foreign key.
- Use of Primary Keys - to uniquely identify each record in a table.
Example:
In a Products table, each product could have a unique ID as the primary key.
- Use of Foreign Keys for Referential Integrity - to maintain consistency across related tables.
Example:
The Orders table might have a CustomerID field that is a foreign key referencing the Customers table.
Note that in Oracle database indexes for foreign keys are not created automatically.
- Appropriate Data Types - to use the most suitable data types for each column to optimize storage and performance.
Example:
Use VARCHAR2 for variable-length strings and NUMBER for numerical values in Oracle.
- Indexing for Performance - to improve query performance.
Example:
Creating an index on frequently searched columns, like creating an index on CustomerID in the Orders table.
- Avoiding Excessive Normalization (Denormalization) - to improve performance by reducing the number of joins needed, particularly in read-heavy databases.
Example:
In a reporting database, you might include the customer's name directly in the Orders table to avoid a join with the Customers table.
- Using Sequences for Auto-Incrementing Fields - to generate unique values for primary key fields.
Example:
Creating a sequence for OrderID in the Orders table to ensure each order has a unique identifier.
- Implementing Audit Trails - to keep track of changes for compliance and debugging.
Example:
Having CreatedDate and LastModifiedDate columns in tables to track when records are created and last updated.
- Designing for Concurrency - to allow multiple users to access and modify data concurrently without conflicts.
Example:
Using Oracle's built-in locking mechanisms and designing transactions to be short to reduce locking conflicts.
- Consider Partitioning for Large Tables - to improve performance and manageability for very large tables.
Example:
Partitioning a Sales table by year or region, so queries on a specific year or region are faster.
- Consistent Naming Conventions - to make the schema easier to understand and navigate.
Example:
Prefixing table names with their functional area, like HR_Employees, FIN_Accounts.
- Planning for Growth - to design a scalable database that can handle increased data volume and user load.
Example:
Anticipating future columns and relationships that might be needed and designing tables with flexibility in mind.
Conclusion
These best practices can guide you in designing a robust, efficient, and scalable database structure in Oracle. The key is to balance normalization for data integrity, denormalization for performance, and a clear understanding of your application's specific requirements.
Resources
Besides Oracle Database Documentation there are several good sources:
- Oracle Base - on of the best sources, including some specific techniques
- Burleson Consulting - legendary site with many tips on performance optimization
- Ask Tom - another legendary site