CourseAI Engineering: The Complete Course · Module 11: Data Stores · part 87 of 105
Part 87 · Module 11: Data Stores

Lab: Wire BrightCart's database, cache and jobs

16 min read·13 Oct 2026
Module 11 · Lab · About 70 minutes · Needs: lessons 1 to 4 of this module (SQL, PostgreSQL, caching, queues and storage)

What you are building

MODULE 11'S PIECE: ONE DATABASE, ONE CACHE, TWO JOBS assistant order lookup CachedOrders TTL 60 s Redis cache copies PostgreSQL + pgvector orders, tickets, articles, chunks Publish, timer enqueue RQ worker re-embed, report S3 bucket nightly CSV check_flow() runs all of it and asserts the counts
The finished piece: lookups go through CachedOrders (blue = BrightCart's code), Redis holds short-lived copies (green), and an RQ worker writes chunks to PostgreSQL and reports to S3 (grey = a file store).

Four lessons built four stores one at a time. This lab joins them into the piece Module 11 adds to BrightCart: a database, a cache and background jobs. Orders and tickets live in PostgreSQL behind a small repository. Help-centre chunks and their vectors sit in the same database with pgvector. Redis keeps 60-second copies of order lookups and drops a copy the moment an order changes. When Priya's team edits an article, an RQ job re-embeds it once, however many times the edit is announced. Every night a second job writes Marta's ticket report to an S3 bucket. The lab ends with one check that runs the whole flow and asserts the counts. No hosted model is called; the only model is the small local embedder from Lesson 2.

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