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2948 questions of the kind that actually get asked — in interviews, in architecture review boards, and by the person who has to run the thing at 3 AM. Every answer states the trade-off rather than the slogan, and says when the obvious choice is the wrong one.

All areas2948 Architecture Fundamentals91 Distributed Systems101 Data Architecture90 Cloud Architecture87 Networking96 API & Integration Architecture87 Reliability & Resilience99 Observability92 Performance & Capacity Engineering100 Security Architecture105 Cost Architecture & FinOps102 Business Architecture103 Architecture Communication102 Enterprise Architecture100 Legacy Modernization102 AI-Era Architecture106 Software Architecture & Engineering93 Architecture Patterns94 Architecture Decision-Making101 The Architect's Meta-Skills102 Delivery & Release Engineering103 Platform Engineering & Developer Experience102 Testing & Quality Architecture102 Data Platform Architecture98 Streaming & Real-Time Data103 Data Governance & Semantics91 Frontend & Experience Architecture101 Edge, Mobile & IoT98 Regulatory & Data Protection Architecture99 Assurance, Audit & Model Risk98
Difficulty Any beginner intermediate advanced

5 questions in Zero-Downtime Migration.

  1. Zero-Downtime Migration intermediate Multiple choice

    A commerce platform must change a database schema while an older application version is still running. What migration pattern prevents downtime, and what is the common mistake?

    2 min answer myntraschema-migrationexpand-contractdeployment
  2. Zero-Downtime Migration advanced Multiple choice

    A hot table needs a column renamed and retyped, across many running instances. What constraint dictates the whole sequence?

    2 min answer expand-contractrolling-deploymentreversibilityverification
  3. Zero-Downtime Migration advanced

    A large sharded MySQL fleet needs a tenant moved between shards with no downtime. How should online data movement, dual writes, cutover and rollback be sequenced?

    2 min answer vitessplanetscaleshardingmigration
  4. Zero-Downtime Migration advanced

    A platform deploying many times a day must change a column type on a very large table with no maintenance window. Walk through the sequence.

    2 min answer zero-downtimeexpand-contractbackfillschema
  5. Zero-Downtime Migration advanced

    Mid-way through an expand-contract migration, the application writes each order's country to both the legacy varchar column and a new normalised column. After the dual-write deploy, write p99 on the orders table rises from 18 ms to 140 ms, but only between 20:00 and 23:00 and only on 2 of 16 shards. Read p99 is flat, CPU sits near 35% and no errors are logged. Where is the time going, and what do you change first?

    3 min answer expand contractbackfillp99shards