--- title: How to Handle One-to-One Dimensions? | #Power BI Course 20 description: When Power BI detects a one-to-one relationship between two dimension tables, it is generally safe but adds unnecessary join overhead. The recommended default... canonical: https://daily.dev/posts/how-to-handle-one-to-one-dimensions-power-bi-course-20-clq84oaxa twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How to Handle One-to-One Dimensions? | #Power BI Course 20 | daily.dev og:description: When Power BI detects a one-to-one relationship between two dimension tables, it is generally safe but adds unnecessary join overhead. The recommended default... og:url: https://daily.dev/posts/how-to-handle-one-to-one-dimensions-power-bi-course-20-clq84oaxa og:image: https://api.daily.dev/og/posts/Clq84oAxA.png og:image:alt: How to Handle One-to-One Dimensions? | #Power BI Course 20 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. # How to Handle One-to-One Dimensions? | #Power BI Course 20 **[Data with Baraa](https://daily.dev/sources/datawithbaraa)** · 5 min read · 0 upvotes · 0 comments ## Summary When Power BI detects a one-to-one relationship between two dimension tables, it is generally safe but adds unnecessary join overhead. The recommended default approach is to merge the two tables into a single dimension using Power Query's merge queries feature with a left join, then disable loading of the secondary table. This keeps the data model clean and aligned with star schema principles. Valid reasons to keep one-to-one relationships include managing very wide tables by splitting columns thematically, or separating sensitive data for row-level security purposes. ## Full article daily.dev links to this article rather than hosting it. 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