accesspatterns.dev

A real DynamoDB-compatible engine runs in this tab, backed by SQLite. Every lesson and every model is a live table you operate yourself, with the cost of each read shown beside the data.

lessons
20 lessons

models
24 models

techniques
40 techniques

Query one customer's orders, then scan the whole table for the shipped ones, and compare what each costs.

Techniques

40 across 24 models

The course

5 tiers, 20 lessons

  1. 01Foundations2

    What an item is, and how the key addresses it.

  2. 02Reads and cost5

    The three ways to read, and what each one charges you.

  3. 03Writing data4

    Putting, changing, and guarding items.

  4. 04Modelling relationships6

    One-to-many, secondary indexes, and sparse indexes.

  5. 05Single-table design3

    One table, one index, many access patterns.

The models

24, easiest first

The full console

every operation, raw request and response

The playground is the same instrument with nothing pre-filled. Build any operation as a form or raw JSON, run it against a seeded table, and read the response, the cost and the latency. Open the playground.

About the engine

It's powered by dynoxide, compiled to WebAssembly, and runs entirely in your browser with nothing to install. Built by Martin Hicks, who also builds dynoxide and Parity Suite, a neutral conformance suite for DynamoDB engines.

This is a preview build, scored by the same conformance suite that backs dynoxide's native build. Several operations are still missing - transactions, vector search, streams, tags and TTL among them - so it isn't a like-for-like replacement for the native engine yet.

Questions

Is this really DynamoDB, or a simulation of it?
It's dynoxide, a DynamoDB-compatible engine compiled to WebAssembly and backed by SQLite. The in-browser engine is a preview build, scored by the same conformance suite that backs dynoxide's native build. Several operations are still missing - transactions, vector search, streams, tags, TTL, backups and export, among others - so it is not yet a like-for-like replacement for the native engine.

Do I need an AWS account or anything installed?
No. The engine runs entirely in this browser tab. There's nothing to sign up for and nothing to install.

Is any of my data sent to a server?
No. Lesson progress, favourites and playground tables are stored only in your browser and never leave it. There's no account and no login.

What does the cost shown beside each read mean?
It's what DynamoDB itself would charge: Count, ScannedCount and ConsumedCapacity, read out live so a Query and a Scan of the same table visibly cost different amounts.

Read the original on accesspatterns.dev ↗