# Database types required to run DataSHIELD

**URL:** <https://datashield.discourse.group/t/database-types-required-to-run-datashield/660>\
**Category:** Developer support\
**Created:** [28 November 2022 12:29 UTC](https://datashield.discourse.group/t/database-types-required-to-run-datashield/660 "2022-11-28T12:29:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![felixw](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@felixw](https://datashield.discourse.group/u/felixw)\
**Post date:** [28 November 2022 12:29 UTC](https://datashield.discourse.group/t/database-types-required-to-run-datashield/660/1 "2022-11-28T12:29:11Z")

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Reading the documentation it is not clear to me which data bases DataSHIELD requires: Is a SQL and a document database (MongoDB) necessary? Or is a SQL database sufficient?

Regards

Felix

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**Author:** ![yannick](https://yyz2.discourse-cdn.com/free1/user_avatar/datashield.discourse.group/yannick/32/19_2.png) [@yannick](https://datashield.discourse.group/u/yannick)\
**Post date:** [28 November 2022 14:14 UTC](https://datashield.discourse.group/t/database-types-required-to-run-datashield/660/2 "2022-11-28T14:14:30Z")

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Hi,

Regarding Opal, it is up to you to decide which database to use. Opal supports MongoDB, PostgreSQL, MariaDB/MySQL. You can even register several databases of different types and then decide which one to use per project.

MongoDB is the one to use when some tables have a lot of variables (~1000 columns is a common SQL database limit).

Note also that if you work with “resources”, you do not need a database at all,

Regards  
Yannick