62,000 products, priced and on the web in 34 shops? No problem. Give me something difficult

A group that runs thirty‑four shops in a dozen countries has a problem that a single‑shop business never meets: the same candle exists thirty times, with thirty names, thirty prices, thirty descriptions, and someone has to keep them honest. Our numbers today: 62,000 master products feeding 317,000 shop products. The answer in aiku is a group catalogue — masters — sitting above the shops. A master product is the thing described once; a shop product is that thing as sold here. The ambition, stated plainly, is that one person at one desk can name, describe, photograph and price the whole range, put it on every website, and every shop follows — and that this is not the hard part of their day. This note is about how the two stay in step, and the three lessons that cost us something.

The shape

Masters mirror the shop catalogue one level up: master departments → master families → master products, owned by a master shop (a group‑level catalogue that several real shops hang off). A master product points at its trade units (the triangle starts here), carries the canonical name, description, images, ingredients and safety text in the source language, and — the part people care about — prices and RRPs per currency.

A shop product linked to a master follows it: name and description flow down (translated), images flow down, and price flows down unless told otherwise. Create a master product and the shops that should carry it get their product minted with the master's values; edit the master and the children are updated through a hydrator that knows which fields are followed.

Majors and minors

Prices live on the master as a per‑currency map: {GBP: 4.68, EUR: 5.52, PLN: …}. Two or three currencies are majors — set by hand by the pricing team. The rest are minors that follow a major at an agreed rate: złoty follows euro at a rate management announced, and so on. Change the major and every minor recalculates; change the agreed rate and a background pipeline recomputes every master in that currency, cascades to the shops, reindexes search, reprices the open baskets, and reports progress on the screen while it runs. A single currency value can be marked independent — a deliberate hand‑set exception that the cascade will never overwrite — and the independence is visible, audited, and rare.

Eleven thousand master products recompute in about three minutes; the baskets take one more.

Follow the master, or don't, at three levels

Sometimes a shop really does need its own price. The switch exists at three levels — the shop ("this shop does not follow master pricing"), the family, the product — enforced in the one cascade that writes prices, with rejoin when the switch is turned back off. A master‑side report lists every "rebel" product so the pricing team can see who has opted out.

Then we measured. Declared rebels: one family and seventy products. Products silently diverging from their master: 33,897, eleven per cent of the followers — not policy, rot, accumulated over years of edits that did not go through the cascade. That audit is why master price editing went from "a screen" to "a project": the cascade is now the only writer, every write is audited per product with the user who caused it, and a repair reconciles the drift in batches with a report before it touches anything.

Three lessons, paid for

Never let a side effect write a price. An editor changed only descriptions in a family bulk‑edit screen; a side effect quietly rewrote the family's master prices with no audit entry. Nobody noticed until a customer did. Now bulk edits of text cannot reach a price field, and pricing deliberately stays out of bulk edit altogether.

Know what basis a number is on. A cascade treated RRP totals as per‑unit and multiplied by the pack size — once per run, so a product with twelve in a pack went ×12, then ×144. It ran on every cascade for a month. The fix was one argument name; the repair rewrote 1,635 values after proving each was within a tolerance of the major × exchange rate, and skipped anything independent, discontinued or opted out. Four thousand ambiguous values went to a human list.

Retire the column that lies. The master still had a scalar price from the single‑currency days. It held a value in the master shop's base currency — which differs per master shop — so reading it as "the price" silently compared pounds with euros. It is deprecated in the code, never read in new paths, and will be dropped. A column whose meaning depends on which row you are on is not a column, it is a trap.

What the catalogue team gets

One place to name, describe, photograph and price a thing; a cascade that takes it to every shop that should have it, in every currency, with an audit line per product; an explicit, visible way to say "not this one"; and reports that say when reality drifted from the rule. The thirty candles are one candle again.