Challenges
26 challenges available.
Transaction Row Validator
A data pipeline ingests daily transaction exports from a payment partner. Each row is validated before insertion into the analytics database. The pipeline must accept all valid rows including zero-amount rows, which represent fee waivers and refund reversals.
Session Cleanup Job
A scheduled background job purges expired user sessions from the sessions table. After deleting, it logs each cleaned-up account for the audit trail. Sessions created by unauthenticated (anonymous) users have no associated user account and carry a null user_id.
Promo Code Discount Processor
A billing job applies promotional discount codes to pending orders before invoice generation. Each code specifies a discount percentage and a minimum purchase amount that the order must meet.
Admin Bulk Import Guard
An internal admin tool allows operators to perform bulk data imports into production tables. Before executing, the tool checks that the requesting operator holds sufficient permission.
Contact Email Normalizer
An ETL job deduplicates contact records imported from multiple sales tools by comparing canonical email addresses. Records sharing the same email should be grouped together before the merge step.
Sales Commission Calculator
A nightly background job computes and records sales commissions for each rep based on the deals they closed during the month.
API Key Rotation Script
An admin script rotates API keys for internal services on a scheduled basis, replacing existing keys with freshly generated ones and persisting the new values to the secrets store.
Inventory CSV Exporter
A scheduled job exports a snapshot of current warehouse inventory to a CSV file that the operations team imports into their planning tool each morning.
Daily Transaction Summary
A nightly reporting job aggregates completed payment transactions for each calendar date and writes summary records used by the finance team's dashboard.
Event Deduplication Processor
A webhook receiver processes events from multiple upstream producers. Producers retry on network errors, so the same event can arrive more than once. The processor deduplicates by event_id before persisting. If the persistence call fails, the caller retries the event — so the processor must remain retryable after a failed write.
User Export Job
A scheduled job exports user account records to a CSV file consumed by the analytics platform. The export accepts a date range and must include only active accounts created within that range. The date range is always inclusive on both ends — a user created on the end date must appear in the export.
Failed Task Retry Manager
A background worker picks up failed tasks from a retry queue, attempts reprocessing, and routes tasks that have exhausted their retry budget to a dead-letter queue for operator review.
Webhook Signature Verifier
A payment processor integration receives signed webhooks and must validate each request before processing. The verifier checks both the HMAC-SHA256 signature and the age of the webhook.
Transaction Metrics Rollup
A nightly background job aggregates per-merchant transaction volumes into a monthly metrics table used by the finance dashboard. The job processes each merchant independently so a bad merchant does not block others.
Subscription Renewal Processor
A nightly job identifies subscriptions coming up for renewal and advances their billing dates so the payment processor can charge customers on the correct schedule.
Report Download Token Issuer
An internal service issues short-lived download tokens that allow external client applications to fetch generated reports without sharing long-lived credentials.
Message Queue Consumer
A background consumer reads tasks from a work queue, dispatches them to a registered handler, and reports per-instance processing statistics for the health dashboard.
Customer Record ETL
A one-time ETL job migrates customer records from a legacy CRM into the new platform, converting date fields from the legacy format and validating that no records are silently dropped during transformation.
Pipeline Checkpoint Writer
A batch processing pipeline consumes messages from a queue, processes them in configurable batches, and checkpoints its progress to object storage after each batch. On restart the pipeline reads the last checkpoint to resume from the correct offset. Consumer acknowledgements tell the broker that messages have been processed; they must not be sent until the checkpoint is durably written.
GDPR Export Pipeline
A GDPR data subject access request pipeline collects personal data from multiple internal microservices, assembles a JSON export bundle, and delivers it to the requesting user. The export must be complete — if any service fails, the pipeline must abort and retry. Internal-only fields must not appear in user-facing exports.
OAuth Token Refresh Job
A daily background job refreshes OAuth access tokens for registered third-party integrations. It exchanges refresh tokens with the OAuth provider, persists new credentials, and writes an audit record for compliance review.
Report Generation Worker
A background worker processes user-submitted report requests from a queue, runs the underlying data query, serialises the result to CSV, and uploads the file to object storage. The job record tracks status so the scheduler can detect and retry failures.
Billing Invoice Generator
A monthly billing job generates invoices for subscription customers by aggregating usage charges and applying any available account credits. The output is stored and queued for payment processing.
Audit Log Export Pipeline
An export pipeline packages audit log events for external compliance auditors, producing either JSON or CSV output at a caller-configured path.
Import Idempotency Guard
A recurring import job ingests records from an upstream system and uses content hashing to skip unchanged records on re-runs, importing only new or modified data.
Ledger Balance Snapshot Writer
A scheduled job reads ledger entries for each account and writes a balance snapshot representing the account's net position as of a specific date.