Shopify replaced Redis with MySQL for inventory reservations–and it scaled
If we get this wrong in one direction, two buyers purchase the same last unit: the merchant has to cancel an order, send an apology email, and eat the support cost. If we get it wrong in the other direction, we tell a buyer something is sold out when it isn't, and the merchant loses a sale they should have made. At Shopify's scale, either failure compounds fast.
- ▪If we get this wrong in one direction, two buyers purchase the same last unit: the merchant has to cancel an order, send an apology email, and eat the support cost.
- ▪If we get it wrong in the other direction, we tell a buyer something is sold out when it isn't, and the merchant loses a sale they should have made.
- ▪At Shopify's scale, either failure compounds fast.
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Record
| Original publisher | Shopify |
| Canonical URL | https://shopify.engineering/scaling-inventory-reservations |
| Publication time | Sat, 08 Aug 2026 22:32:50 +0000 |
| Retrieval time | 2026-08-09T01:05:42.093Z |
| Last seen | 2026-08-09T01:05:42.093Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | O489laMKXRcP · 1 stories |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
blog|InfrastructureWe replaced Redis with MySQL for inventory reservations—and it scaledHow we used SKIP LOCKED, composite primary keys, and connection visibility to hit our scale targets.Published on May 12, 2026Engineering at ShopifyWe’re hiringSee open rolesDuring checkout, when a buyer clicks "Complete purchase," we need to guarantee the items they're buying are still available. If we get this wrong in one direction, two buyers purchase the same last unit: the merchant has to cancel an order, send an apology email, and eat the support cost. If we get it wrong in the other direction, we tell a buyer something is sold out when it isn't, and the merchant loses a sale they should have made. At Shopify's scale, either failure compounds fast.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Shopify.
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