Learning Hub
Learn databases by running them
Free interactive courses for developers, DBAs and architects. Examples run in your browser against a seeded sample database, and progress stays on your device. No account, no install.
From the first query to sharded clusters: CRUD, aggregation, indexes and explain(), schema design, transactions, replication, sharding, WiredTiger internals and Percona tooling. Every example runs against a seeded database in your browser.
Curriculum
Lessons from beginner to architect, each with runnable examples and a quiz.
Playground
A mongosh-style shell with explain plans and stage-by-stage pipelines.
Exercises
Auto-checked problems compared against a reference solution.
Production scenarios
Debug slow queries, failed index builds, TTL issues and a point-in-time restore.
Build projects
Checkout without overselling, a job queue with leases, chat, telemetry rollups, multi-tenant SaaS and a flexible catalogue.
Interview prep
Developer, DBA, architect, aggregation, performance, sharding, security and system design questions, mock interviews and a 100-question final assessment.
Certification track
Associate Developer and DBA objectives with timed practice exams.
Guides
Architecture, performance, internals and version differences.
Docker labs
Real replica set and sharded cluster drills: failover, rollback, PBM restore.
Coming from PostgreSQL
A concept map, the defaults that surprise PostgreSQL DBAs, and your daily SQL translated to queries and pipelines.
A real PostgreSQL 18 server runs in your browser, so every example, plan and catalog query is genuine. From the first SELECT to window functions and JSONB, EXPLAIN ANALYZE and indexing, MVCC, VACUUM and WAL, then replication, sharding and production architecture, and on to pgvector, hybrid search and RAG.
Curriculum
Lessons from beginner to architect, each with runnable SQL and a quiz.
SQL console
A psql-style console with \d meta-commands, visual EXPLAIN ANALYZE plans and a schema browser.
Exercises
Auto-checked problems, from basic filters to blocking chains and replication slots.
Production scenarios
Fix missing indexes, sequence drift, bad estimates, bloat and a missing partition.
Build projects
A payments ledger, multi-tenant SaaS with row-level security, a job queue, time series and RAG search, built step by step.
Labs
Read B-tree pages with pageinspect, age and freeze a table with real VACUUMs, step through two sessions fighting over locks and fail over a three-node cluster.
Docker labs
A real Patroni cluster with pgBackRest, plus a 16 to 18 logical replication upgrade: failover, pg_rewind, PITR.
Interview prep
SQL, performance, internals, HA, scaling, AI and system design questions, mock interviews and a 100-question final assessment.
Guides
Performance, internals, operations, and what changed from PostgreSQL 12 to 19.
Coming from MongoDB
A concept map, the PostgreSQL defaults that cause early incidents, and your daily queries translated to SQL.
From the course to your own clusters
The courses teach the model; DBHelm runs it on real deployments. Connect your self-hosted MongoDB and PostgreSQL on Kubernetes or VMs to see explain plans, index usage, replication lag and slow queries in one place.