# Tableau 2020.2: The new data model and relationships

> This is content from just-tim, the data-and-analytics channel by Tim Ngwena (formerly 'Tableau Tim'). Tim has 12+ years of hands-on BI experience and covers Tableau most of all, plus Power BI, Looker, Hex, SQL and data modelling, the analytics industry, and the craft of doing the job — always tool-agnostic and honest about the trade-offs.

- **Author:** Tim Ngwena (just-tim, https://just-tim.com/about)
- **Published:** 2020-05-06
- **Format:** Video · 15 min watch · transcript available
- **Topics:** Data prep, Data visualisation, Tool strategy
- **Tools:** Tableau (data blending, data modelling, joins, relationships)
- **Canonical:** https://just-tim.com/posts/tableau-2020-2-the-new-data-model-and-relationships
- **Watch:** https://www.youtu.be/75zvHrnuPr0

I walk through the new data model introduced in Tableau 2020.2, focusing on relationships and the distinction between the logical and physical layers. Using the beta bookshop sample dataset, I demonstrate how relationships differ from traditional joins and blends, and where each still has its place.

## Key takeaways

- The data model works on two levels: a logical layer where you define relationships between tables, and a physical layer where traditional joins and unions still live
- Relationships let Tableau figure out aggregation and avoid duplication behind the scenes, with each view generating its own unique query to the data source
- Joins and blends are not removed — use a join when you need a join calculation (like concatenating two IDs) by opening a table into the physical layer
- Relationships make it easy to answer questions from any table's perspective, such as finding authors with zero published books, without creating separate connections or blends
- Cardinality and referential integrity settings ship with sensible defaults — leave them alone unless you understand those concepts, as they can produce odd results

## Chapters

- 0:00 What the data model adds
- 0:24 Connecting and creating a relationship
- 1:58 Logical versus physical layers
- 3:16 When you still need a join
- 6:01 The new sheet interface
- 8:21 Querying from any table's perspective
- 11:01 Tableau's reference resources
- 13:27 Advanced relationship settings

Watch the full video, read the transcript and use chapter deep-links on the page: https://just-tim.com/posts/tableau-2020-2-the-new-data-model-and-relationships

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just-tim — Data and analytics, with a point of view. · https://www.youtube.com/channel/UC7HYxRWmaNlJux-X7rNLZyw · https://twitter.com/TableauTim · https://www.linkedin.com/in/timngwena