--- title: Copying data is not an anti-pattern. Copying data... description: The common advice to never duplicate data and always maintain a single source of truth breaks down in real distributed systems. The CAP theorem makes clear... canonical: https://daily.dev/posts/copying-data-is-not-an-anti-pattern-copying-data-without-a-strategy-is--f86im5ezw twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Copying data is not an anti-pattern. Copying data without a strategy is. | daily.dev og:description: The common advice to never duplicate data and always maintain a single source of truth breaks down in real distributed systems. The CAP theorem makes clear... og:url: https://daily.dev/posts/copying-data-is-not-an-anti-pattern-copying-data-without-a-strategy-is--f86im5ezw og:image: https://api.daily.dev/og/posts/F86im5EZw.png og:image:alt: Copying data is not an anti-pattern. Copying data without a strategy is. 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. # Copying data is not an anti-pattern. Copying data without a strategy is. **[ITNEXT](https://daily.dev/sources/itnext)** · 4 min read · 1 upvotes · 0 comments ## Summary The common advice to never duplicate data and always maintain a single source of truth breaks down in real distributed systems. The CAP theorem makes clear that when network partitions occur, you must choose between consistency and availability. Caching local copies of data is not an anti-pattern — it is a deliberate architectural choice that trades some consistency for resilience and independence. Hidden copies already exist everywhere (API responses in memory, queue messages, CQRS read models), so the real question is whether you have an explicit strategy for staleness, invalidation, and divergence. Systems that acknowledge their copies and manage them intentionally are safer than those that pretend copies don't exist. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Cache consistency: strategies to keep data fresh](https://daily.dev/posts/cache-consistency-strategies-to-keep-data-fresh-o2gww6sna) · Redis · 6 upvotes · 0 comments --- Tags: [#career](https://daily.dev/tags/career), [#data-engineering](https://daily.dev/tags/data-engineering), [#distributed-systems](https://daily.dev/tags/distributed-systems) [View this post on daily.dev](https://daily.dev/posts/copying-data-is-not-an-anti-pattern-copying-data-without-a-strategy-is--f86im5ezw) ```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":"Copying data is not an anti-pattern. 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