--- title: Cosmos DB for Event Sourcing? The Cost of Building Your... description: Building an event store on Azure using Cosmos DB, Azure Functions, Service Bus, and Redis requires your team to implement all core event-sourcing primitives... canonical: https://daily.dev/posts/cosmos-db-for-event-sourcing-the-cost-of-building-your-own-event-store-tso0zegd8 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Cosmos DB for Event Sourcing? The Cost of Building Your Own Event Store | daily.dev og:description: Building an event store on Azure using Cosmos DB, Azure Functions, Service Bus, and Redis requires your team to implement all core event-sourcing primitives... og:url: https://daily.dev/posts/cosmos-db-for-event-sourcing-the-cost-of-building-your-own-event-store-tso0zegd8 og:image: https://api.daily.dev/og/posts/tso0zEgD8.png og:image:alt: Cosmos DB for Event Sourcing? The Cost of Building Your Own Event Store og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Cosmos DB for Event Sourcing? The Cost of Building Your Own Event Store **[Event Store](https://daily.dev/sources/eventstore)** · 12 min read · 0 upvotes · 0 comments ## Summary Building an event store on Azure using Cosmos DB, Azure Functions, Service Bus, and Redis requires your team to implement all core event-sourcing primitives from scratch: stream abstraction, optimistic concurrency, global ordering, projections, subscriptions, replay, and idempotency. Each capability becomes a custom development project, and the resulting system distributes operational complexity across six or more services. KurrentDB, a purpose-built event store, provides these as native database features — including a globally ordered $all stream, built-in projections, a SQL Sink connector, persistent and catch-up subscriptions, causation/correlation metadata, and multi-stream atomic appends. The post also argues that a proper event store is foundational for AI workloads, providing temporal, causal, relational, and semantic context that DIY approaches make expensive to access. Cost predictability, Day 2 maintainability, and Azure-native monitoring integration via Prometheus and Grafana are also covered. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Writing Events Is All You Need](https://daily.dev/posts/writing-events-is-all-you-need-rjvxyoggv) · Event Store · 0 upvotes · 0 comments - [Build AI apps with Azure Cosmos DB: Key trends from Cosmos Conf 2026](https://daily.dev/posts/build-ai-apps-with-azure-cosmos-db-key-trends-from-cosmos-conf-2026-9il8x8opp) · Microsoft Azure · 0 upvotes · 0 comments - [Event Sourcing: Why we built our own “library”](https://daily.dev/posts/event-sourcing-why-we-built-our-own-library--zfmbth6bv) · We Are .NET · 18 upvotes · 0 comments - [We'll End Up Where We Started. Except with Different Technology.](https://daily.dev/posts/we-ll-end-up-where-we-started-except-with-different-technology--5h7gm44uu) · Event Store · 0 upvotes · 0 comments --- Tags: [#architecture](https://daily.dev/tags/architecture), [#backend](https://daily.dev/tags/backend), [#distributed-systems](https://daily.dev/tags/distributed-systems) [View this post on daily.dev](https://daily.dev/posts/cosmos-db-for-event-sourcing-the-cost-of-building-your-own-event-store-tso0zegd8) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Cosmos DB for Event Sourcing? 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