PostgreSQL supports table inheritance, a powerful feature that allows tables to inherit structure and data from other tables. This enables database designers to model complex real-world relationships efficiently.
🔹 Understanding PostgreSQL Inheritance
Inheritance in PostgreSQL allows a child table to automatically acquire the columns of a parent table. This is useful for scenarios where multiple tables share common attributes but also require unique fields.
🔹 Basic Example: Cities and Capitals
We demonstrate how a capitals table can inherit from a cities table, making data retrieval more streamlined. Queries on the parent table can include data from child tables, but you can also filter specific tables using the ONLY keyword.
🔹 Querying Inherited Data
- Retrieve all records (including inherited rows)
- Query only parent table records using
ONLY - Identify source tables using the
tableoidsystem column
🔹 Limitations & Constraints
While CHECK and NOT NULL constraints are inherited, primary keys, unique constraints, and foreign keys are not. This video explores how to work around these limitations effectively.
🔹 Advanced Inheritance Features
- Multiple Inheritance – A table can inherit from multiple parent tables, merging attributes from all.
- Dynamic Inheritance – Modify inheritance relationships on the fly using
ALTER TABLE. - Dropping Parent Tables – Child tables must be handled carefully before dropping a parent table.
🔹 Real-World Applications
We explore practical use cases where inheritance simplifies schema design, improves query performance, and enhances access control.
📌 Conclusion
PostgreSQL inheritance is a flexible tool for organizing database schemas, but it has limitations regarding constraints, indexing, and insert behavior. Understanding these aspects will help you design efficient and scalable databases.
🚀 Next Topic: Table Partitioning in PostgreSQL – Stay tuned!
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