1. Data Lifecycle & Retention advanced

    A GDPR erasure request arrives for a customer. Where does their data actually live, and what makes this expensive to retrofit?

    2 min answer gdprerasureprivacylifecycle
  2. Data Lifecycle & Retention advanced

    A consumer fintech accumulates transaction, behavioural and derived data. How should retention, archival, deletion and regulatory holds be designed so they do not conflict?

    2 min answer credretentiondeletionlegal-hold
  3. Data Lifecycle & Retention advanced

    A customer exercises their right to erasure. List every place their data plausibly exists in a mature architecture and how each is handled.

    3 min answer lifecycledeletiongdprbackups
  4. Data Lifecycle & Retention advanced

    A file storage platform must permanently delete a user's data on request, while maintaining backups, replicas, caches and search indexes. What makes this genuinely difficult, and how is it designed?

    3 min answer data-lifecycledeletionbackupscrypto-shredding
  5. Data Warehousing advanced

    A finance report double-counts revenue after a new fact table is added. What is the likely modelling error?

    2 min answer warehousegrainfan-outdimensional-modelling
  6. Data Warehousing advanced

    A travel platform runs thousands of experiments simultaneously and needs its warehouse to support reliable analysis. What warehouse design decisions prevent cross-experiment contamination and infrastructure artefacts from being read as results?

    2 min answer warehouseexperimentationdata-modellingbooking
  7. ETL & ELT advanced

    A daily pipeline has been producing wrong numbers for three weeks due to a logic bug. What must be true of the architecture for the fix to be a one-day job?

    3 min answer eltbackfillidempotencyairflow
  8. Event Sourcing advanced

    A brokerage proposes event sourcing for its account ledger. What requirements would genuinely justify it, and when is conventional state plus an audit trail the safer choice?

    2 min answer growwevent-sourcingauditledger
  9. Event Sourcing advanced

    A neobank stores every account change as an immutable fact rather than a mutable balance. Which needs justify this, how are balances materialised for fast reads, and what happens when a projection is found to be wrong?

    3 min answer nubankevent-sourcingledgerimmutability
  10. Event Sourcing advanced Multiple choice

    A system is event-sourced. A customer exercises their right to erasure. The event log is immutable. How do you comply?

    2 min answer event-sourcinggdprcrypto-shreddingprivacy
  11. Event Sourcing advanced

    A team wants event sourcing for a new order service, citing audit requirements. What do you recommend?

    2 min answer event-sourcingauditdecision-making
  12. Event Sourcing advanced Multiple choice

    An organisation wants event sourcing for its order platform because it is considered scalable. What business or audit requirements would actually justify it, and when is CRUD plus an audit log safer?

    2 min answer event-sourcingaudittemporal-queriesalibaba