pg_accumulator — Python Demo

A simple web application demonstrating the core capabilities of the pg_accumulator extension.

What It Demonstrates

  • Register creation — register_create() (runs automatically on startup)
  • Posting movements — register_post() via a web form
  • Canceling documents — register_unpost()
  • Current balances — reading from balance_cache (O(1))
  • Balance queries — inventory_balance() with filters and historical dates
  • Movement history — browsing recent operations

Getting Started

cd demo/python
docker compose up --build

Open in browser: http://localhost:3301

Project Structure

demo/python/
  app.py               — Flask backend
  templates/index.html  — Web interface
  init.sql              — Register creation + seed data
  docker-compose.yml    — PostgreSQL with pg_accumulator + Flask app
  Dockerfile            — Flask container

Demo Walkthrough

  1. Open http://localhost:3301
  2. See initial balances (6 movements are pre-loaded)
  3. Post a new receipt: receipt:5, warehouse 1, product 1, quantity 50, amount 25000
  4. Observe that the balance updates instantly
  5. Cancel document receipt:5 — the balance reverts to its previous state
  6. Query balance at date 2026-04-05 — see the warehouse state at that historical point

Shutdown

docker compose down -v