AZ-305 · Question #399
Hotspot Question You have an Azure subscription. You plan to deploy a high-throughput transactional workload that will use PostgreSQL. You need to recommend a managed solution for storing relational…
This question tests knowledge of Azure managed PostgreSQL services and their capabilities for horizontal scaling of transactional writes using row-based sharding with minimal administration.
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Answer Area
- Azure service:Azure Cosmos DB for PostgreSQLAzure Database for PostgreSQL flexible serverAzure Database for PostgreSQL single server
- Scalability technique:Distributed tablesLogical replicationNear-zero downtime scaling
Explanation
This question tests knowledge of Azure managed PostgreSQL services and their capabilities for horizontal scaling of transactional writes using row-based sharding with minimal administration.
Approach. The correct recommendation is Azure Cosmos DB for PostgreSQL (formerly Azure Database for PostgreSQL - Hyperscale Citus). This service provides native support for horizontal scaling of transactional writes through row-based sharding using the Citus extension, which distributes data across multiple worker nodes (shards). It is a fully managed service, meaning Azure handles patching, backups, high availability, and monitoring - minimizing administrative effort. The Citus-based sharding model distributes rows of a table across shards using a distribution column, enabling parallelized transactional write workloads that scale horizontally beyond what a single PostgreSQL node can handle.
Concept tested. Azure Cosmos DB for PostgreSQL (Hyperscale Citus) is the correct managed Azure service for PostgreSQL workloads requiring horizontal scaling of transactional writes via row-based sharding. Standard Azure Database for PostgreSQL - Flexible Server supports vertical scaling but not native horizontal sharding of writes, making it unsuitable for this requirement. Understanding the distinction between these managed PostgreSQL offerings and their scaling architectures is the key concept being tested.
Reference. https://learn.microsoft.com/en-us/azure/cosmos-db/postgresql/introduction
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