#Database

85 questions

What are the pros and cons of TypeORM?Node.js#databaseMiddle
What are the pros and cons of Sequelize?Node.js#ormMiddle
How do TypeORM and Sequelize compare, and when would you choose each?Node.js#ormSenior
What is SQL and what is it used for?SQL#databaseJunior
How does NULL behave in SQL?SQL#databaseJunior
What are primary keys and foreign keys?SQL#databaseMiddle
What database constraints are there?SQL#databaseMiddle
What is database normalization?SQL#databaseMiddle
What are transactions and ACID properties?SQL#databaseMiddle
What are views and materialized views?SQL#databaseMiddle
What are transaction isolation levels?SQL#databaseSenior
What causes deadlocks and how do you prevent them?SQL#databaseSenior
What are stored procedures and when should you use them?SQL#databaseSenior
What are DDL, DML, DCL and TCL?SQL#databaseSenior
What are common SQL data types and how do you choose them?SQL#databaseMiddle
How do you query 10B records under 100ms?System Design#databaseSenior
How would you shard a database for 1 billion users?System Design#databaseSenior
How do you scale MySQL when traffic grows 100x?System Design#databaseSenior
How do you store 100M log events per day?System Design#databaseSenior
How do you build full-text search over 100M+ records?System Design#searchingSenior
Real-time revenue analytics over millions of transactions/day: how?System Design#databaseSenior
Store & query transaction history for hundreds of millions of accountsSystem Design#scalingSenior
Migrate a 10TB database with zero downtime: what is the plan?System Design#data-migrationSenior
Backup & disaster recovery for a database of tens of TBSystem Design#databaseSenior
How do you import 100M CSV records into a DB fast?System Design#performanceSenior
How do you design an audit log for years of traceability?System Design#loggingSenior
How does CDC sync data across systems?System Design#databaseMiddle
How do you partition a single table with billions of rows?System Design#sqlMiddle
How do you export a huge dataset without impacting the live system?System Design#performanceMiddle
How do you handle a hot key or hot row under heavy contention?System Design#performanceMiddle
How do you prevent deadlocks with thousands of concurrent transactions?System Design#concurrencyMiddle
What is PostgreSQL and why choose it?PostgreSQL#databaseJunior
What data types does PostgreSQL offer beyond standard SQL?PostgreSQL#databaseJunior
What is psql and what are its essential commands?PostgreSQL#databaseJunior
How do auto-incrementing IDs work (SERIAL, sequences, IDENTITY)?PostgreSQL#databaseJunior
What are schemas in PostgreSQL?PostgreSQL#databaseJunior
How do array columns work in PostgreSQL?PostgreSQL#databaseJunior
What are generated columns?PostgreSQL#databaseJunior
How does JSONB work and when should you use it?PostgreSQL#databaseMiddle
How does full-text search work in PostgreSQL?PostgreSQL#databaseMiddle
What is MVCC in PostgreSQL?PostgreSQL#databaseMiddle
What are PostgreSQL extensions?PostgreSQL#databaseMiddle
What are LISTEN and NOTIFY?PostgreSQL#databaseMiddle
What constraints does PostgreSQL support?PostgreSQL#databaseMiddle
How does locking work in PostgreSQL?PostgreSQL#databaseSenior
What is MongoDB and how does it differ from SQL databases?MongoDB#databaseJunior
What are documents and collections in MongoDB?MongoDB#databaseJunior
What is BSON and what data types does MongoDB support?MongoDB#databaseJunior
What is the MongoDB shell (mongosh) and its essential commands?MongoDB#databaseJunior
How does text search work in MongoDB?MongoDB#databaseMiddle
How do transactions work in MongoDB?MongoDB#databaseMiddle
What is Mongoose and why use an ODM?MongoDB#databaseMiddle
How does schema validation work in MongoDB?MongoDB#databaseMiddle
What are change streams?MongoDB#databaseSenior
How do write concern and read concern affect consistency?MongoDB#databaseSenior
What is Redis and what is it used for?Redis#databaseJunior
What data types does Redis support?Redis#databaseJunior
How do strings and keys work in Redis?Redis#databaseJunior
How does key expiration (TTL) work in Redis?Redis#databaseJunior
How do Redis lists work and how are they used for queues?Redis#databaseJunior
How do Redis hashes and sets work?Redis#databaseJunior
What are sorted sets and how are they used?Redis#databaseJunior
What is redis-cli and its essential commands?Redis#databaseJunior
How does Redis differ from a traditional database?Redis#databaseJunior
How does Redis persistence work (RDB vs AOF)?Redis#databaseMiddle
How do Redis transactions work?Redis#databaseMiddle
Why are Redis operations atomic and why does it matter?Redis#databaseMiddle
How does Lua scripting work in Redis?Redis#databaseSenior
What advanced Redis data structures and modules exist?Redis#databaseSenior
What is Amazon DynamoDB?Cloud & AWS#databaseMiddle
How do you optimize a slow database query?Site Reliability & Operations#databaseMiddle
How does Spring Data JPA work and what are derived queries?Spring Boot#springMiddle
How does @Transactional work, including propagation and rollback?Spring Boot#databaseMiddle
What is MySQL, and how do InnoDB and MyISAM differ?MySQL#databaseJunior
How do you choose data types in MySQL, and what are common pitfalls?MySQL#databaseJunior
What is an index, and how does a primary key differ from a secondary index?MySQL#databaseJunior
Explain INNER, LEFT, and RIGHT JOIN in MySQL with examples.MySQL#databaseJunior
How do B-tree, composite, and covering indexes work, and what is the leftmost-prefix rule?MySQL#databaseMiddle
How do you read EXPLAIN and use it to optimize a slow query?MySQL#performanceMiddle
Explain transactions and isolation levels in InnoDB, and the anomalies they prevent.MySQL#databaseMiddle
What are the trade-offs between normalization and denormalization?MySQL#databaseMiddle
How does MySQL master–replica replication work, and how does it help read scaling?MySQL#databaseMiddle
How do row locks and MVCC work in InnoDB, and how do you avoid deadlocks?MySQL#databaseSenior
When do you reach for partitioning versus sharding to scale MySQL?MySQL#databaseSenior
How do you tune a MySQL server: buffer pool, slow query log, and connections?MySQL#performanceSenior