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Backend Interview Questions

52 questions to help you prepare for your next interview.

Read Uncommitted (Dirty Reads)

Transactions and ACID

Composite Indexes

Understanding Connection Pooling

Index Covering Joins

Covering Indexes

Clustered vs Non-Clustered Indexes

Handling Deadlocks

Safe Online Schema Migrations

Database Normalization

Table Partitioning

Database Replication Basics

Database Sharding Concept

Database Triggers

Denormalization Concept

Analyzing Query Performance

Functional (Expression) Indexes

ON DELETE CASCADE

Disabling Foreign Key Checks

Unindexed Foreign Keys

Heap-Only Tuples (HOT) Updates

B-Tree vs Hash Indexes

Read Committed Isolation

Serializable Isolation

Keyset Pagination (Cursor)

Materialized Views

Multi-Version Concurrency Control (MVCC)

Mitigating N+1 with Batching

Solving N+1 with Eager Loading

Nested Transactions & Savepoints

Optimistic Locking via Timestamps

Optimistic Locking

Pessimistic Locking Example

Optimizing ORDER BY with Indexes

Partial Indexes

Pessimistic Locking (FOR UPDATE)

SQL Injection & Prepared Statements

Index Scan vs Sequential Scan

Application-Level Read-Write Splitting

Row-Level Security (RLS)

Implementing Soft Deletes

SQL Injection Mitigation

Two-Phase Commit (2PC)

Upsert (ON CONFLICT)

Optimizing Lookups with Indexes

UUID vs Auto Increment

Write-Ahead Logging (WAL)

Write Amplification in Indexes