Database Selector
What is database selection?
Database selection chooses the ownership and transaction boundary that will protect correctness while serving the system's hardest access paths.
Step 1
Model
Model the primary data shape, transaction scope, hardest query, consistency contract, traffic, latency, failure domains, and operating team before naming products.
Step 2
Observe
Use the ranked categories to expose contradictions, companion-store boundaries, and the conditions that should trigger a future migration.
Step 3
Challenge
Build a healthy baseline, then inject a hot tenant, region partition, schema wave, or analytical surge and watch the decision boundary move.
Choose the ownership boundary first
Model the data and transaction contract, set the operating envelope, then inject the failure that could invalidate an otherwise attractive choice.
Challenge the healthy design
Scenario pressure changes the same ranking; it is not a separate quiz result.
Distributed SQL
Illustrative category · CockroachDB · YugabyteDB · Spanner-style systems
Relational transactions spread across failure domains through a distributed consensus layer. Relational workloads that require multi-node or multi-region survivability.
Why it ranks here
- Its distributed sql model fits the relational ownership shape.
- The joins path is native to this category.
- It can keep the declared multi-record invariant inside one transaction boundary.
- Its normal contract can support strict reads and writes within the modeled boundary.
Contradictions to resolve
- The operating model assumes expertise the current team does not have.
Evaluate the declared workload without an injected fault. Benchmark the hardest query, recovery behavior, and migration path before selecting a product.
Data locality, transaction span, and schema changes must be tested against consensus latency.
- Cross-region transaction latency exceeds the user-facing budget.
- Hot ranges concentrate writes despite adding nodes.
- Operational complexity outweighs the value of distributed writes.