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This is a medium difficulty System Design question, commonly asked during Technical Screen rounds at xAI.

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This question is commonly asked for Software Engineer candidates at xAI during technical interviews.

Explain ACID and transactions | xAI Interview Question

Quick Overview

This question evaluates understanding of ACID transactional properties and the mechanisms that enforce them—including logging (undo/redo), locking, MVCC, and write-ahead logging—along with knowledge of SQL isolation levels and common transactional anomalies.

ACID Transactions: Definitions, Enforcement, Isolation Levels, and Example

Context

You are designing a service backed by a relational database that supports transactions. Explain the ACID properties and how real systems implement them to ensure correctness under failures and concurrency.

Tasks

Define the ACID properties: atomicity, consistency, isolation, and durability.
Explain how systems enforce these properties using:
- Logging (undo/redo),
- Locking (e.g., two-phase locking),
- MVCC (multi-version concurrency control), and
- Write-Ahead Logging (WAL).
Discuss SQL isolation levels and common anomalies they (do/do not) prevent.
Provide a concrete example transaction that demonstrates ACID end-to-end.

ACID Transactions: Definitions, Enforcement, Isolation Levels, and Example

Context

Tasks

Define the ACID properties: atomicity, consistency, isolation, and durability.
Explain how systems enforce these properties using:
- Logging (undo/redo),
- Locking (e.g., two-phase locking),
- MVCC (multi-version concurrency control), and
- Write-Ahead Logging (WAL).
Discuss SQL isolation levels and common anomalies they (do/do not) prevent.
Provide a concrete example transaction that demonstrates ACID end-to-end.

Explain ACID and transactions

Quick Overview

ACID Transactions: Definitions, Enforcement, Isolation Levels, and Example

Context

Tasks

Solution

Comments (0)

Explain ACID and transactions

Quick Overview

ACID Transactions: Definitions, Enforcement, Isolation Levels, and Example

Context

Tasks

Solution

Comments (0)