--- title: Event sourcing: non-bi-temporal events in a bi-temporal... description: Part nine of an event sourcing series explores how to handle non-bi-temporal (uni-temporal or perpetual) events within a bi-temporal event stream. Using... canonical: https://daily.dev/posts/event-sourcing-non-bi-temporal-events-in-a-bi-temporal-stream-8scwvqj99 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Event sourcing: non-bi-temporal events in a bi-temporal stream | daily.dev og:description: Part nine of an event sourcing series explores how to handle non-bi-temporal (uni-temporal or perpetual) events within a bi-temporal event stream. Using... og:url: https://daily.dev/posts/event-sourcing-non-bi-temporal-events-in-a-bi-temporal-stream-8scwvqj99 og:image: https://api.daily.dev/og/posts/8SCWVQj99.png og:image:alt: Event sourcing: non-bi-temporal events in a bi-temporal stream 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. # Event sourcing: non-bi-temporal events in a bi-temporal stream **[We Are .NET](https://daily.dev/sources/wearedotnet)** · 5 min read · 0 upvotes · 0 comments ## Summary Part nine of an event sourcing series explores how to handle non-bi-temporal (uni-temporal or perpetual) events within a bi-temporal event stream. Using real-world examples like organisational unit name changes and person name changes, the author explains the 'perpetual modification' pattern — where certain events apply their changes across all timeline phases regardless of effective date. The post covers the trade-off between separating uni-temporal and bi-temporal events into dedicated streams versus combining them, and dives into how the bi-temporal projector applies perpetual events only to phases created by events with smaller application timestamps, preventing newer effective-dated events from being overridden. F# code and test cases from 2019 are included. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Event Sourcing: set-and-remove-based bi-temporal events](https://daily.dev/posts/event-sourcing-set-and-remove-based-bi-temporal-events-8de56bzad) · We Are .NET · 1 upvotes · 0 comments - [Event Sourcing: the not-so-simple bi-temporal basics](https://daily.dev/posts/event-sourcing-the-not-so-simple-bi-temporal-basics-t4ntaclgn) · We Are .NET · 0 upvotes · 0 comments - [Event Sourcing: undo set-remove-based bi-temporal events – because we must](https://daily.dev/posts/event-sourcing-undo-set-remove-based-bi-temporal-events-because-we-must-y6cpmwees) · We Are .NET · 0 upvotes · 0 comments --- Tags: [#architecture](https://daily.dev/tags/architecture), [#domain-driven-design](https://daily.dev/tags/domain-driven-design) [View this post on daily.dev](https://daily.dev/posts/event-sourcing-non-bi-temporal-events-in-a-bi-temporal-stream-8scwvqj99) ```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":"Event sourcing: non-bi-temporal events in a bi-temporal stream","url":"https://daily.dev/posts/event-sourcing-non-bi-temporal-events-in-a-bi-temporal-stream-8scwvqj99","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/event-sourcing-non-bi-temporal-events-in-a-bi-temporal-stream-8scwvqj99"},"datePublished":"2026-06-09T09:13:09.185Z","dateModified":"2026-06-09T09:13:32.721Z","description":"Part nine of an event sourcing series explores how to handle non-bi-temporal (uni-temporal or perpetual) events within a bi-temporal event stream. 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