# What is the purpose of the semantic layer in Reportr?

**URL:** <https://communitysupport.group/t/what-is-the-purpose-of-the-semantic-layer-in-reportr/19>\
**Category:** Reportr\
**Created:** [October 16, 2026, 9:27pm UTC](https://communitysupport.group/t/what-is-the-purpose-of-the-semantic-layer-in-reportr/19 "2026-10-16T21:27:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tv90210](https://avatars.discourse-cdn.com/v4/letter/t/a9a28c/32.png) [@tv90210](https://communitysupport.group/u/tv90210)\
**Post date:** [October 16, 2026, 9:27pm UTC](https://communitysupport.group/t/what-is-the-purpose-of-the-semantic-layer-in-reportr/19/1 "2026-10-16T21:27:07Z")

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Am I required to create a semantic layer before using the chat feature?

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**Author:** ![Johnny](https://avatars.discourse-cdn.com/v4/letter/j/ecb155/32.png) [@Johnny](https://communitysupport.group/u/Johnny)\
**Post date:** [October 16, 2026, 9:38pm UTC](https://communitysupport.group/t/what-is-the-purpose-of-the-semantic-layer-in-reportr/19/2 "2026-10-16T21:38:47Z")

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A semantic layer is not required. As long as you have a database connection you can select the connection and chat with the database.

If your database has been in use for awhile it probably has accumulated a lot of ad hoc changes over time. For example, columns like flag1 and flag2 whose meanings are not obvious, tables that are no longer in use, relationships between tables that exist but are not defined in the database and so on. This is known as **schema rot**. AI can struggle to understand your schema in this situation.

The solution is to add a **semantic layer**. You can select tables that should be included in the semantic layer and exclude columns that are not to be used. You can set business names and add descriptions for each column. If there are relationships missing in the database you can add virtual relationships in the semantic layer. AI uses the semantic layer as a **roadmap** to your database. The difference is night and day. When you select the semantic layer as the data source you will see a big difference in AI’s ability to answer your questions.

For more info: [Reportr — Chat With Your Database](https://reportr.com/#semantic)