What is PostgreSQL?
PostgreSQL is a powerful, open-source object-relational database system with a strong emphasis on extensibility and standards compliance. It offers advanced features like ACID compliance, foreign keys, joins, views, triggers, and stored procedures.
40K+
Transactions/sec
ACID
Compliance
TB
Data capacity
30+
Years mature
ACID Properties Explained
Atomicity
Transactions are all-or-nothing operations
Example: Bank transfer completes fully or not at all
Consistency
Database remains in valid state after transactions
Example: Foreign key constraints are always maintained
Isolation
Concurrent transactions don't interfere with each other
Example: Read Committed, Serializable isolation levels
Durability
Committed changes survive system failures
Example: WAL (Write-Ahead Logging) ensures persistence
Core Concepts
ACID Properties
Fundamental properties ensuring reliable database transactions
Key Features
- Atomicity
- Consistency
- Isolation
- Durability
Example
Bank transfer: either both debit and credit occur, or neither does🧮 PostgreSQL Performance Calculator
Database Configuration
Performance Metrics
Connections200
Memory Usage1156 MB
Throughput750 TPS
Checkpoint Target90%
Write I/O spread over checkpoint interval
Scaling Patterns
Read Replicas
Scale read operations with multiple replica databases
Implementation
Streaming replication with hot standby servers✅ Advantages
- Increased read capacity
- Load distribution
- High availability
- Zero downtime failover
⚠️ Challenges
- Read lag
- Complexity
- Storage overhead
- Consistency challenges
Transaction Isolation Levels
Read Uncommitted
Lowest isolation level, allows dirty reads
Issues: Dirty reads, non-repeatable reads, phantom reads
Read Committed (Default)
Only reads committed data, prevents dirty reads
Issues: Non-repeatable reads, phantom reads
Repeatable Read
Consistent reads within transaction
Issues: Phantom reads (PostgreSQL prevents these too)
Serializable
Highest isolation, equivalent to serial execution
Issues: None, but potential serialization failures
🏢 Real-world Implementations
Instagram: Photo Metadata
• 400+ million photos uploaded daily
• JSONB for flexible metadata storage
• Read replicas for global access
• Partitioning by upload date
Pattern: JSONB for schema flexibility, read replicas for scale
Stripe: Payment Processing
• ACID compliance for financial data
• Serializable isolation for critical operations
• Foreign keys for data integrity
• WAL archiving for compliance
Pattern: ACID compliance, strict consistency, audit trails
Reddit: Content & Comments
• Hierarchical data with recursive queries
• Full-text search with GIN indexes
• Connection pooling with PgBouncer
• Read/write splitting
Pattern: Tree structures, full-text search, connection pooling
Spotify: Music Catalog
• 70+ million songs in catalog
• GiST indexes for similarity search
• Materialized views for analytics
• Horizontal partitioning by region
Pattern: Advanced indexing, materialized views, geographic partitioning
💡 Key Takeaways
- • ACID Compliance: Critical for financial and transactional applications
- • MVCC Benefits: High concurrency without read locks
- • Proper Indexing: Choose the right index type for your query patterns
- • Connection Pooling: Essential for high-concurrency applications
- • Read Replicas: Scale reads geographically and by workload
- • Monitoring: Track connections, query performance, and resource usage
📝 PostgreSQL Mastery Quiz
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