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
- 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 - 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…
- Precedent Transactions
- Acid
- Isolation Levels
Introduction to Database Systems - 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
- Query Optimization
- Explain Analyze
Introduction to Database Systems - CodeIntermediateNew
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…
- Blockchain Indexing
- Typescript
- Ethereum
Blockchain and Decentralized Systems Engineering Practice your coursework on real scenarios.
Every challenge is shaped from real industry context — not generic exercises. The work mirrors what your degree prepares you for.
Why Ewance
- 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 - AnalysisIntermediateNew
Tune Concurrency Control on a Multi-Tenant OLTP Database
Capture 6 hours of pg_locks + pg_stat_activity snapshots during peak. Identify the top 8 contention hotspots and classify each (row-level conflict, deadlock cycles, FOR UPDATE p…
- Concurrency Control
- Lock Contention
- Postgresql Or Mysql
Advanced Database 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 - StrategyIntermediateNew
Design a Multi-Region Blue/Green Database Deployment for an EdTech Platform
Design the migration: source PostgreSQL 14 (primary in São Paulo) to target PostgreSQL 16 (primary in Mexico City, replica in Bogotá). Use logical replication for zero-downtime …
- Blue Green Deployment
- Logical Replication
- Postgresql Or Mysql
DevOps and Secure Deployment - Browse challenges
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Product Manager
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.
- AnalysisSeniorNew
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
- Postgresql Planner
- Extended Statistics
Advanced Database Systems - AnalysisBeginnerNew
Audit Data Quality for a Climate Tech Sensor Network
You receive 30 days of ingested sensor data (around 400 million rows) plus the sensor inventory and known maintenance windows. Define a set of data-quality expectations (null ra…
- Data Quality
- Great Expectations
- Anomaly Detection
Data Engineering and Big Data Systems - CodeIntermediateNew
Build an Event-Sourced Inventory System for a Warehouse
Design the event model: 12-15 events covering the warehouse lifecycle. Implement using EventStoreDB (or Kafka + a snapshotting projection layer) in Go or C#. Build at least 3 re…
- Event Sourcing
- Cqrs
- Eventstoredb
Event-Driven Architecture - 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…
- Software Architecture
- C4 Model
- Data Modeling
Software Engineering Foundations 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
- 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
- Delta Lake
- Apache Spark
Data Engineering and Big Data Systems - CodeIntermediateNew
Apply Hexagonal Architecture to a Payments Microservice
Design the settlement domain in pure Kotlin (no Spring imports, no framework annotations). Define ports for: payment-network adapter (one inbound per network — SEPA, Faster Paym…
- Hexagonal Architecture
- Ports And Adapters
- Kotlin Programming
Domain-Driven Design - 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 - DesignIntermediateNew
Design a Real-Time Order Pipeline for a Fintech Payments Platform
You receive a synthetic Kafka stream of around 500 transactions per second, a static merchant dimension table (about 80,000 rows), and a daily FX rate snapshot. Design an end-to…
- Streaming Data
- Kafka Event Streaming
- Stream Processing
Data Engineering and Big Data 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 - 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
- Knowledge Representation
- Rule Based Reasoning
Artificial Intelligence: Principles and Techniques - 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
- Data Modeling
Cloud Computing for Data and ML - 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 - CodeIntermediateNew
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
- Debezium
- Kafka Event Streaming
Big Data and Data-Intensive Systems - 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
- State Space Search
- Classical Planning
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 - StrategyBeginnerNew
Migrate a Local-Government Records System from MySQL to PostgreSQL
Audit the MySQL schema (around 60 tables) for incompatibilities (case-folding identifiers, ENUM types, TIMESTAMP semantics, character sets). Plan a migration using pgloader for …
- Database Migration
- Postgresql Or Mysql
- Postgresql Or Mysql
Introduction to Database Systems
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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