---
title: "Tableau data sources reading unmodelled tables | Metacenta"
description: "A Tableau data source over a table your pipeline does not build sits outside its tests. How we match workbook tables to the pipeline, and when to leave it."
url: "https://metacenta.com/rules/tableau-reads-unknown"
updated: "2026-10-14"
tokens: 517
---

BI semantic layer · rule tableau-reads-unknown

# Tableau data sources reading unmodelled tables

A Metacenta review checks this under the rule **Tableau data sources read tables the warehouse layer builds**. Everything below applies whether or not you ever commission one.

## What this rule checks

For each Tableau data source that reads named database tables, this rule flags it when a table matches nothing the transformation layer builds or declares as a source. We compare names only, not schemas.

## Why it matters

Its dashboards sit outside the tested pipeline. A change upstream cannot warn anyone that it will break them.

## How to fix it

**Point Tableau data sources at modelled tables.** Point the data source at the modelled table that serves it. If another pipeline builds that table on purpose, tell us, and the finding comes out of your report.

## When it is fine to leave

A small table maintained by hand, such as a list of targets, loaded straight into the warehouse. Load it through the pipeline as a seed when you can, so it is tested too.

## What we need to check it

Tableau `.twb` or `.twbx` workbooks, plus a warehouse-side artefact: `manifest.json`, a SQL project or a lineage export. Without one, the rule declines. Excel sheets, text files, extracts and custom SQL are not matched. Findings are medium confidence.

[Ask about a review](https://metacenta.com/enquire?src=rule-tableau-reads-unknown&via=md)

## Related pages

- [dbt semantic models reading unbuilt columns](https://metacenta.com/rules/semantic-column-not-built)
- [dbt semantic model keys with no unique test](https://metacenta.com/rules/semantic-primary-entity-unasserted)
- [Looker views reading tables dbt does not know](https://metacenta.com/rules/lookml-view-unbuilt-table)
- [Looker views reading raw dbt sources](https://metacenta.com/rules/lookml-view-reads-raw-source)
- [A sample review, as a client reads it](https://metacenta.com/sample)
- [All published rules](https://metacenta.com/rules)
- [How a review is assessed](https://metacenta.com/standard)