Full-Stack & Backend Database Master: SQL, NoSQL, Redis & System Design

What is a Database Management System (DBMS), and what are the foundational differences between Relational (SQL) and Non-Relational (NoSQL) databases?

Walk me through your production database architecture experience and database selection criteria.

How do you handle schema migrations without downtime?

Describe a severe database performance issue you resolved.

Strategy for database security and connection pooling:

What are the ACID properties in relational databases?

Normalization (1NF to BCNF) vs Denormalization:

Primary Key vs Unique Key vs Foreign Key:

SQL Transaction Isolation Levels:

Dirty Reads vs Non-Repeatable Reads vs Phantom Reads:

How do B-Tree indexes work internally?

Clustered Index vs Non-Clustered Index:

Composite Index and the "Leftmost Prefix Rule":

EXPLAIN vs EXPLAIN ANALYZE:

SQL Joins comparison:

Join Execution Algorithms (Nested Loop, Hash Join, Merge Join):

PostgreSQL JSONB and GIN Indexes:

Database Connection Pooling (PgBouncer):

Deadlocks in SQL transactions:

Table Partitioning vs Sharding:

Stored Procedures, Triggers, and Views:

Soft Deletes and Partial Indexes:

Write-Ahead Logging (WAL) and PITR:

MVCC and VACUUM in PostgreSQL:

The N+1 Query Problem in ORMs:

CAP Theorem:

When to choose MongoDB over PostgreSQL:

MongoDB: Embedding vs Referencing:

MongoDB Aggregation Pipeline:

MongoDB Compound & Multikey Indexes:

Replica Sets vs Sharded Clusters in MongoDB:

MongoDB Oplog & Change Streams:

MongoDB Transactions:

Write Concerns & Read Concerns:

TTL (Time-To-Live) Indexes:

DynamoDB Partition Keys, Sort Keys & Hot Partitions:

DynamoDB GSI vs LSI:

Optimistic vs Pessimistic Locking:

Eventual Consistency:

Wide-Column (Cassandra) vs Graph (Neo4j):

Why single-threaded Redis handles 100k+ ops/sec:

Core Redis Data Structures:

Caching Strategies:

Cache Stampede vs Penetration vs Avalanche:

Redis Eviction Policies:

Redis Persistence: RDB vs AOF:

Redis Sliding Window Rate Limiter:

Distributed Locks in Redis (Redlock):

Redis Pub/Sub vs Redis Streams:

When Redis caching is architectural overkill:

Read-Write Splitting (Primary/Replica):

Change Data Capture (CDC):

Database Sharding:

Database Failover & Leader Election (Raft):

The Transactional Outbox Pattern:

Full-Text Search: Elasticsearch vs SQL LIKE vs tsvector:

Time-Series Databases (TimescaleDB, InfluxDB):

Connection Starvation & Circuit Breakers:

Vector Databases (pgvector, Pinecone) & HNSW:

RPO vs RTO Disaster Recovery: