Quick Note — Recommend a Solution for Database Scalability
AZ-305 › Unit 2 › Design data storage for relational data › Recommend a solution for database scalability
Quick Note — Recommend a Solution for Database Scalability
Reference: Designing Microsoft Azure Infrastructure Solutions (AZ-305) — the attached exam study guide is the source material for this lesson.
Retrieval target
- Recommend a Solution for Database Scalability
- Closed-book recall
- 5 minutes
- Open the full lesson after a miss
Decision anchors
| Prompt | Compact answer |
|---|---|
| Vertical vs horizontal scaling | Vertical (scale-up/down) — change the size of one resource (e.g., 2 → 8 vCores on one DB). Requires a restart on most resources; not used for autoscaling. Horizontal (scale-out/in) — add or remove instances behind a router/load balancer. No downtime, the basis for all Azure autoscale. Relational engines combine both: tier up for write capacity, replicas out for read capacity. |
| Read scale-out (Azure SQL) | A read-only secondary replica usable by clients that pass ApplicationIntent=ReadOnly in the connection string — the gateway routes those connections to the replica; default ReadWrite goes to the primary. Available in Business Critical and Hyperscale tiers; General Purpose doesn't have it. Replica lag is small but non-zero — applications must tolerate eventual-consistency reads. |
Sharding (database) | Horizontally partition data across many databases (shards), each holding a slice keyed by a sharding key (tenant ID, customer ID, region). A separate shard map manager database records which key maps to which shard; the app library reads this map to route each request. Pattern of choice for SaaS multi-tenant scale beyond a single DB's limits. |
Elastic Pool | A fixed pool of vCores or DTUs shared by multiple SQL DBs on the same server. Per-DB min/max caps bound noisy neighbors. Cost is the pool's, not per DB — best for many low-utilization DBs with occasional spikes. Adding / removing a DB to a pool is online. Cannot mix DTU and vCore models in one pool, cannot span servers. |
Read the answers once, then cover the right-hand column and reconstruct each one from the prompt. A useful answer names the requirement, the recommended control or service boundary, and the nearest alternative it rejects. If you can only recognize the answer after seeing it, retrieval is not yet secure.
Ninety-second explanation
Without notes, explain:
- What requirement signals this learning objective rather than a neighbouring one?
- Which two solution families are most likely to be compared?
- Which hard constraint eliminates the strongest distractor?
- What identity, network, data, or failure boundary must appear in the design?
- Which operational test would prove the recommendation works?
Then compare your explanation with the full lesson. Record the missing decision rule—not merely the missed product name—in your error log.
When to open the full lesson
Open the curriculum-linked lesson when you cannot explain a comparison, when a scenario depends on a numeric limit or SKU feature, or when the service is on a retirement path. Use current Microsoft Learn documentation for availability, limits, pricing, naming, and migration milestones; the quick note is intentionally compact.
Source and freshness
Derived from the linked AZ-305 lesson and retrieval deck, grounded in both attached course sources. Reviewed 2026-08-02. Current Microsoft documentation controls changing product contracts.