Learn by trying
Playgrounds
A worked example gives you an answer to follow. A playground lets you change the question. Start with a guided lesson, predict a result, then alter the inputs and see what happens.
Databases and storage
SQL sandbox
Run PostgreSQL in your browser. Join a shop’s records, test a constraint, keep a purchase together, or investigate how a query does its work. Guided lessons provide the starting data and explain the results; you can edit every statement.
Your practice database belongs to the tab. Resetting restores its starting point, so you can try a different approach. The lessons explain when an experiment needs a full server or several connections.
Start with Relational databases for the ideas behind these experiments, or use the local practice guide to run PostgreSQL on your computer.
Databases and storage
Object-storage sandbox
Follow an object request through conditional writes, unfinished uploads and version recovery. Guided lessons also explore dataset publication, cache freshness, event processing, cost and filtered vector ranking.
This playground runs a small local teaching model inspired by Amazon S3. It makes no AWS requests and needs no account. Inspect the state after each request, edit the inputs and restart to try another outcome.
Read the object-storage collection for the mechanisms, or use the real-S3 worksheet to test actual service requests.