Forward Deployed Engineer interview question · Most asked
Design an integration that syncs records from a customer's CRM into your product every 15 minutes.
Summary
Authenticate with OAuth client credentials (least-privilege scopes, secrets in a manager), backfill history in throttled, checkpointed batches, then sync incrementally using an updated-since watermark with an overlap window and idempotent upserts keyed by source ID. Handle pagination with cursors, rate limits with Retry-After and jittered backoff, validate and quarantine bad records, monitor freshness and errors, and handle deletes (tombstones or periodic reconciliation).
Longer Answer
Mention schema mapping agreed with the data owner, contract tests against a sandbox, and a status view showing last successful sync for the customer.
Key Points
- OAuth, least privilege, secret manager.
- Throttled backfill, incremental sync.
- Idempotent upserts, overlap window.
- Validation, monitoring, deletes.
Deep dive: Forward Deployed Engineering Tutorial: Incremental Sync and Backfills
Explanation
What interviewers look for
End-to-end reliability: auth, pagination, rate limits, idempotency, data quality, observability.
Follow-up questions
- How do you detect records the sync missed?
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