Distributed
← Data modeling & storage

Lesson 06.1

SQL vs key-value / document

Relational, key-value, and document databases arrange data around different access patterns and guarantees, so the best fit depends on the reads, writes, relationships, and invariants a system needs.

One order with several related rows

Ava and Ben work in a cookie shop. An order connects a customer, items, payment, and stock, and the computer must update them together.

In this lesson you'll

  1. 1Follow one run and learn how to read the picture
  2. 2Predict what changes before revealing the result
  3. 3Compare the choices and help Ava get one complete, valid order without too much waiting