1️⃣ Fundamentals of Databases
What is a database?
RDBMS vs NoSQL (when to choose which)
ACID vs BASE
Transactions and Isolation levels
OLTP vs OLAP
2️⃣ SQL & Relational Databases (PostgreSQL, MySQL, SQLite)
🔸 SQL Basics
SELECT, INSERT, UPDATE, DELETE
WHERE, ORDER BY, LIMIT, OFFSET
GROUP BY, HAVING
Joins: INNER, LEFT, RIGHT, FULL OUTER
Subqueries and CTEs (WITH)
🔸 Schema Design
Tables, columns, primary/foreign keys
Normalization (1NF, 2NF, 3NF)
Indexes (B-Tree, GIN, BRIN)
Constraints: UNIQUE, CHECK, NOT NULL
ENUMs, composite keys
🔸 PostgreSQL-Specific Features
JSONB fields & indexing
Array fields
Full-text search
Custom data types
Upserts (ON CONFLICT)
Window functions
Materialized views
Extensions (pgcrypto, uuid-ossp, postgis, etc.)
🔸 Performance & Optimization
Query plans and EXPLAIN
Index types and when to use
Vacuum and autovacuum
Connection pooling
Partitioning and sharding
3️⃣ NoSQL Databases
🔸 Overview & Comparison
Document, Key-Value, Graph, Columnar
When to use NoSQL over RDBMS
CAP theorem
4️⃣ MongoDB (Document-Oriented NoSQL)
🔸 Core Concepts
Documents & Collections
BSON format
Schema-less design (vs schema validation)
🔸 CRUD in Mongo
find(), insertOne(), updateOne(), deleteOne()
Query operators ($gt, $in, $or, etc.)
Projection, sorting, pagination
🔸 Advanced Features
Aggregation framework (equivalent to SQL’s GROUP BY)
Indexing
Transactions in MongoDB (v4.0+)
Data modeling patterns (embedded vs referenced)
🔸 MongoDB Atlas & Cloud Tools
Backups & replication
Triggers and functions
Monitoring & performance
5️⃣ Migrations & Schema Management
🔸 SQL Tools
Manual migrations vs migration tools (Alembic, Flyway, Liquibase)
Django ORM migrations (makemigrations, migrate)
🔸 MongoDB
Schema evolution strategies
Versioning documents manually
6️⃣ Security & Best Practices
SQL injection & query safety
Proper use of parameterized queries
Role-based access control (RBAC)
Encrypting sensitive data (at rest & in transit)
Auditing & logging
7️⃣ Backup, Restore, Replication & Scaling
Backups (logical vs physical)
PITR (Point-in-time recovery)
Master-slave replication
Multi-master, read replicas
Sharding strategies
High availability setups (e.g., Patroni for Postgres)
8️⃣ Advanced Querying & Tools
Query tuning and profiling
Using ORMs (Django ORM, SQLAlchemy) vs raw SQL
Database GUI tools (DBeaver, pgAdmin, Compass for Mongo)
Writing reusable views and stored procedures
Using EXPLAIN ANALYZE, profiling slow queries
9️⃣ DevOps & Database in Production
Environment-specific configs (local, staging, prod)
Connection pooling (PgBouncer)
Using .env securely
DB monitoring tools (pg_stat_statements, Mongo Profiler)
🔟 Data Integrity & Validation
Application-level vs DB-level validation
Triggers & stored procedures for enforcing logic
Using Django or Pydantic with validation layers
🧭 Suggested Note Series
Note # Topic
DB Notes #1 RDBMS vs NoSQL – Core Concepts
DB Notes #2 SQL Deep Dive (with PostgreSQL)
DB Notes #3 MongoDB for Backend Devs
DB Notes #4 Indexing, Performance & Query Optimization
DB Notes #5 Secure & Scalable Database Architecture
DB Notes #6 Real-World Modeling: Blog, Shop, Game, etc.
DB Notes #7 Migrations, Backups, and DevOps Practices
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