PostgreSQL

What is PostgreSQL?

PostgreSQL is an advanced, enterprise-class, and open-source relational database system. It supports both SQL (relational) and JSON (non-relational) querying. PostgreSQL is a highly stable database backed by more than 20 years of community development which has contributed to its high levels of resilience, integrity, and correctness.

-- Create a table
CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username VARCHAR(50) UNIQUE NOT NULL,
    email VARCHAR(100) UNIQUE NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    profile JSONB
);

-- Insert data
INSERT INTO users (username, email, profile) VALUES 
('john_doe', 'john@example.com', '{"age": 30, "city": "New York"}'),
('jane_smith', 'jane@example.com', '{"age": 25, "city": "San Francisco"}');

-- Query with JSON operations
SELECT username, profile->>'city' as city 
FROM users 
WHERE (profile->>'age')::int > 25;

-- Advanced query with window functions
SELECT 
    username,
    email,
    created_at,
    ROW_NUMBER() OVER (ORDER BY created_at) as user_number
FROM users;

-- Create index for performance
CREATE INDEX idx_users_profile_city 
ON users USING GIN ((profile->>'city'));
                

Key Features

• ACID Compliance: Ensures data integrity with Atomicity, Consistency, Isolation, Durability
• JSON Support: Native JSON and JSONB data types for flexible data storage
• Advanced Indexing: Multiple index types including B-tree, Hash, GiST, SP-GiST, GIN, and BRIN
• Full-Text Search: Built-in full-text search capabilities
• Extensibility: Support for custom functions, operators, and data types
• Concurrency: Multi-version concurrency control (MVCC)
• Replication: Built-in streaming replication and logical replication

Career Impact

Learning Path

1. Learn SQL fundamentals
2. Understand relational database concepts
3. Practice PostgreSQL-specific features
4. Learn performance optimization
5. Master backup and recovery
6. Explore advanced features (JSON, extensions)