# Google Pub/Sub - Data Streaming (Data Engineering) > Topics, subscriptions, push vs pull, ordering, dead lettering, exactly-once delivery, monitoring, schema registry - 20 interview questions - Senior - [Interview Questions: Data Engineering](https://sharpskill.dev/en/technologies/data-engineering/interview-questions.md) ## 1. What is the main architectural characteristic of Google Pub/Sub? **Answer** Google Pub/Sub is a serverless asynchronous messaging service that decouples message producers from consumers. Publishers send messages to topics without knowing the subscribers, and subscribers receive messages via subscriptions without knowing the publishers. This architecture enables independent horizontal scaling on both sides. ## 2. What is the fundamental difference between a topic and a subscription in Pub/Sub? **Answer** A topic is a named channel to which publishers send messages, while a subscription is a named entity representing a subscriber's interest in receiving messages from a topic. A topic can have multiple subscriptions, and each subscription receives a copy of every message published to the topic. ## 3. When should a pull subscription be preferred over a push subscription? **Answer** A pull subscription is preferable when the subscriber needs to control the message consumption rate (flow control), process large batches, or when the execution environment cannot expose a public HTTPS endpoint. Pull also makes it easier to handle load spikes by dynamically adjusting the number of messages retrieved. ## 17 more questions available - How does the acknowledgement mechanism work in Pub/Sub? - What is the role of a dead letter topic in Pub/Sub? Sign up for free: https://sharpskill.dev/en/login ## Other Data Engineering interview topics - [Linux & Shell - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/linux-shell-basics.md): 20 questions, Junior - [Git & GitHub - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/git-github-fundamentals.md): 20 questions, Junior - [Advanced Python for Data Engineering](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/python-advanced-de.md): 25 questions, Junior - [Docker - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/docker-fundamentals.md): 25 questions, Junior - [Google Cloud Platform - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/gcp-fundamentals.md): 20 questions, Junior - [CI/CD and Code Quality](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/ci-cd-code-quality.md): 20 questions, Mid-Level - [Docker Compose](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/docker-compose.md): 20 questions, Mid-Level - [FastAPI - Data APIs](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/fastapi.md): 20 questions, Mid-Level - [Advanced SQL for Data Engineering](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/sql-advanced-de.md): 20 questions, Mid-Level - [Data Lake - Architecture and Ingestion](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/data-lake.md): 20 questions, Mid-Level - [BigQuery for Data Engineering](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/bigquery-de.md): 20 questions, Mid-Level - [PostgreSQL - Administration](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/postgresql-admin.md): 20 questions, Mid-Level - [Data Modeling for Data Engineering](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/data-modeling-de.md): 20 questions, Mid-Level - [Fivetran & Airbyte - Data Ingestion](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/fivetran-airbyte.md): 20 questions, Mid-Level - [dbt - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/dbt-fundamentals-de.md): 20 questions, Mid-Level - [Apache Airflow - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/airflow-fundamentals.md): 20 questions, Mid-Level - [Kubernetes - Fundamentals](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/kubernetes-fundamentals.md): 20 questions, Mid-Level - [dbt - Advanced Features](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/dbt-advanced-de.md): 20 questions, Senior - [ETL / ELT / ETLT Patterns](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/etl-elt-patterns.md): 20 questions, Senior - [Apache Airflow - Advanced](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/airflow-advanced.md): 20 questions, Senior - [Airflow + dbt - Pipeline Orchestration](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/airflow-dbt-integration.md): 20 questions, Senior - [PySpark - Large-Scale Processing](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/pyspark.md): 20 questions, Senior - [Apache Beam & Dataflow](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/apache-beam-dataflow.md): 20 questions, Senior - [Kubernetes - Production and Scaling](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/kubernetes-advanced.md): 20 questions, Senior - [Terraform - Infrastructure as Code](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/terraform.md): 20 questions, Senior - [NoSQL Databases](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/nosql-databases.md): 20 questions, Senior - [Modern Data Architecture](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/data-architecture.md): 20 questions, Senior - [Monitoring and Observability](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/monitoring-observability.md): 20 questions, Senior - [IAM and Data Security](https://sharpskill.dev/en/technologies/data-engineering/interview-questions/iam-security-de.md): 20 questions, Senior --- Source: SharpSkill (https://sharpskill.dev), tech interview preparation for your real stack. HTML version of this page: https://sharpskill.dev/en/technologies/data-engineering/interview-questions/pubsub-streaming