Computer Science
Database & Storage Challenges
Database & Storage challenges put you inside the work of designing data layers that stay fast and correct under load. You'll develop skills in Data Modeling, Database Schema design, and Domain Modeling, and you'll write SQL with JOINs & Aggregations against PostgreSQL or MySQL.
From there you'll handle the harder edges — Indexing strategy, Query optimization, Replication basics, and Multi-region writes — working through High availability & disaster recovery and Oracle database administration the way data teams actually do. Each challenge you solve earns a verified credential you can share with recruiters.
Recommended Challenges
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Design a Change-Data-Capture Pipeline for an E-Commerce Reseller
Receive the MySQL schema (220 tables), 7 days of binlog samples, and the data team's freshness + correctness requirements. Design the CDC pipeline: Debezium for MySQL binlog cap…
- Change Data Capture
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- Kafka Event Streaming
Big Data and Data-Intensive Systems - DesignIntermediateNew
Design a Transactional Schema for a SaaS Order-Provisioning System
Design the schema for orders, quota packs, consumption events, and refunds. Define each critical transaction (buy, consume, refund) with isolation level and locking strategy. Id…
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Optimizing Inventory for a São Paulo D2C Cosmetics Brand
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Diagnose and Fix Query-Planner Misestimates in a FinTech Warehouse
For each of the 6 queries, capture EXPLAIN (ANALYZE, BUFFERS) and compare estimated vs actual rows at each node. Identify the misestimate source per query (single-column stats s…
- Query Optimization
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- Extended Statistics
Advanced Database Systems Practice your coursework on real scenarios.
Every challenge is shaped from real-world context — not generic exercises. The work mirrors what your degree prepares you for.
Why Ewance
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SAT-Based Planner for Smart-Grid Demand Response
Encode the dispatch problem (which customers to curtail by how much, respecting per-customer contractual caps and grid-cell totals) as a SAT or MaxSAT instance. Solve 50 histori…
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Automated Planning - DesignBeginnerNew
Design the Architecture for a Library Management System
Read the 30-page replacement RFP. Author a 15-page architecture document covering the C4 model levels 1-3 (context, container, component) for the new system: web app, mobile app…
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Software Engineering Foundations - CodeIntermediateNew
Migrate a Legacy Warehouse to a Lakehouse for an Edtech AI Platform
You receive a Postgres dump of around 50 GB and the current dbt models that produce the student-attempts mart. Land the raw data in object storage (S3 or GCS) as Parquet partiti…
- Lakehouse Architecture
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Data Engineering and Big Data Systems - CodeIntermediateNew
Design an Anti-Corruption Layer for a Legacy Hospital EHR
Map the legacy EHR's HL7 v2 message schema (ADT, ORM, ORU segments) to the new platform's domain (Patient, Encounter, Order, Result). Identify the 6-10 anti-patterns in the lega…
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Domain-Driven Design - Browse challenges
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Ship product that solves real user problems. Combine user research, prototyping, and stakeholder alignment to turn ambiguous briefs into measurable wins — the role at the centre of modern software teams.
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Build an Indexer for an On-Chain DeFi Analytics Product
Receive the 6 protocols' ABIs + the team's required event coverage spec (around 40 event types). Build a TypeScript indexer using viem + Postgres: subscribe to new blocks via We…
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- Ethereum
Blockchain and Decentralized Systems Engineering - AnalysisBeginnerNew
Add Indexes to a Slow FinTech Reporting Database
Read the 6 reporting queries and capture their EXPLAIN ANALYZE output on staging (a refresh of prod, around 90M rows). Identify the minimum set of indexes that improves all 6 by…
- Indexing Strategy
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- Explain Analyze
Introduction to Database Systems - CodeIntermediateNew
Build a Feature Store Backbone for a Healthtech ML Team
You receive synthetic wearable telemetry (heart rate, accelerometer, sleep stages) for around 5,000 patients across 90 days, plus the existing scattered feature scripts from the…
- Feature Engineering
- Data Modeling
- Python Or Javascript
Data Engineering and Big Data Systems - CodeBeginnerNew
GPU Cost Dashboard for an AI Consulting Practice
Pull AWS Cost and Usage Report, GCP billing export, and Lambda Labs invoices into a single Parquet table. Implement a tagging convention (project + client + experiment_id) and a…
- Cloud Cost Attribution
- Etl Pipelines
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Cloud Computing for Data and ML Build a verifiable portfolio.
Submissions become evidence. Reviewers with shipping experience score against a rubric; the result becomes a credential anyone can verify.
Why Ewance
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Audit Data Quality for a Climate Tech Sensor Network
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- Anomaly Detection
Data Engineering and Big Data Systems - DesignBeginnerNew
Optimizing Inventory for a Toronto D2C Cosmetics Brand
Your task is to design a multidimensional data model (star schema) for inventory management, create an ETL pipeline to load sample data (provided as CSV files), and develop an O…
- Data Warehousing
- Etl Fundamentals
- Olap
Business Intelligence - DesignFoundationalNew
Model and Normalize a Vet-Clinic SaaS Schema
Read the current schema dump (PostgreSQL, around 28 tables, heavily denormalized) and the team's 8 most common reporting queries. Produce an entity-relationship diagram from the…
- Data Modeling
- Normalization
- SQL
Introduction to Database Systems - CodeIntermediateNew
Hierarchical Plans for an Aerospace Maintenance Crew Scheduler
You receive a synthetic week of 80 work orders with hierarchical decompositions, technician certifications, and shared-tool constraints. Implement an HTN planner (PyHOP or HDDL …
- Htn Planning
- Domain Modeling
- Constraint Handling
Automated Planning - CodeIntermediateNew
Reason over a Climate Policy Knowledge Graph for an EU Think Tank
Design a knowledge graph schema covering regulations, member states, sectors, transposition dates, and source-document citations. Ingest a curated dataset of around 200 nodes th…
- Knowledge Graphs
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Artificial Intelligence: Principles and Techniques - CodeIntermediateNew
Multi-Tenant SaaS Backend with Postgres Row Security
Design the multi-tenant schema: shared tables with a tenant_id column, indexed appropriately. Write a forward + backward migration (using Drizzle or Prisma). Implement Postgres …
- Multi Tenant Architecture
- Postgresql Or Mysql
- Row Level Security
Web Application Development - DesignSeniorNew
Designing a Data Warehouse for a Renewable Energy Firm
You are given sample data from three sources: energy production logs, weather data, and equipment maintenance records. Your task is to: (1) design a star schema with fact and di…
- Data Warehousing
- Star Schema
- Etl Fundamentals
Database Systems - CodeBeginnerNew
Design a Domain Model for a Library Loan System (Java)
Implement, in Java 21, an Item type hierarchy (Book, AudioBook, Periodical, EquipmentLoan — each with sub-type-specific rules), Member with eligibility logic, Loan as an aggrega…
- Python Or Javascript
- Oo Design
- Domain Modeling
Object-Oriented Programming and Design - CodeIntermediateNew
Java EE Backend for Sustainable Fashion Marketplace
You are to build a RESTful API for EcoThreads using Java EE (Servlets, JPA, and MySQL). The API must support CRUD operations for products (with categories, sustainability rating…
- Java Ee
- REST API Design
- Jpa
Web and Mobile Application Development - CodeIntermediateNew
Plan Warehouse Pick Routes with a Classical Planner
You receive a stylized warehouse map (aisle graph), 30 sample shifts of pick tasks, and the current heuristic's outputs. Write a PDDL domain + problem generator, solve with at l…
- Pddl Modeling
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Automated Planning - AnalysisBeginnerNew
Author a Ubiquitous-Language Glossary for a Telco Billing Domain
Conduct 12 structured interviews (30 min each) with stakeholders across CRM, billing, AR, customer portal, and finance. Capture each team's terminology for the top 25 domain con…
- Ubiquitous Language
- Context Mapping
- Stakeholder Interviews
Domain-Driven Design - CodeIntermediateNew
Add Idempotency Keys to a Payment Webhook System
Read the current Go webhook-sender code and 30 days of duplicate-delivery incident logs. Design the idempotency scheme: server-generated key per event (UUID v7 — time-ordered), …
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- Idempotency
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API Design and GraphQL
How it works
From brief to credential, in six steps.
Step 01
Browse challenges aligned to your studies.
Step 02
Accept the one that fits your goals.
Step 03
Work through it with AI Copilot guidance.
Step 04
Submit for structured evaluation.
Step 05
Earn a verified credential.
Step 06
Add it to LinkedIn with one click.
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