Relational Database Fundamentals and Design Questions

Core concepts of relational databases and schema design including tables, relationships such as one to one one to many and many to many, primary keys and foreign keys, data integrity constraints, and the properties of atomicity consistency isolation and durability and why they matter. Understand differences between relational systems using structured query language and nonrelational databases, indexing strategies, normalization and denormalization trade offs, simple query optimization techniques, and when to choose a normalized relational design versus a document or key value store. Candidates should be able to perform basic entity identification, produce simple schema diagrams, explain persistence and durability considerations, and reason about basic performance and scaling trade offs.

MediumSystem Design

24 practiced

Design a relational schema for a product catalog that supports multiple product variants (size/color), hierarchical categories, and inventory levels per warehouse. Your design should optimize for fast product page reads (low latency) while supporting consistent inventory updates. Describe tables, keys, typical indexes, and where you might denormalize.

EasyTechnical

20 practiced

List common integrity constraints (NOT NULL, UNIQUE, CHECK, FOREIGN KEY, DEFAULT) and explain how each helps maintain data quality. Provide examples where CHECK constraints prevent invalid business data and discuss cross-database portability issues with CHECK and other constraints.

HardTechnical

24 practiced

Design a backup and point-in-time recovery (PITR) strategy for a MySQL/InnoDB deployment with an RPO of 15 minutes and RTO of 30 minutes across multiple regions. Include physical vs logical backups, binary log management, retention, testing restores, and cross-region considerations.

EasyTechnical

23 practiced

Explain the difference between row-level triggers and statement-level triggers in SQL databases. Give two practical use cases for triggers and discuss potential pitfalls (performance impact, hidden side effects, order of execution, and recursion).

HardTechnical

25 practiced

Explain how Multi-Version Concurrency Control (MVCC) works internally and how snapshot isolation differs from true serializability. Describe an example of a write-skew anomaly and how you would prevent it in a DBMS that provides snapshot isolation.

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