# Data retention, shared data extensions and relationships

*Marketing Cloud Engagement Specialist Study Guide · Subscriber and Data Management · Last updated October 29, 2026 · https://www.certifyforce.com/study-guide/marketing-cloud-engagement-specialist/subscriber-and-data-management/data-retention-shared-data-extensions-and-relationships*

Which data retention option deletes rows, all records or the whole data extension; how triggered send source data extensions are built and retained; how shared data extension folders give business units access; and how Data Designer links data extensions with matching data types, the right cardinality and the Contact Key.

- Certification: Salesforce Marketing Cloud Engagement Specialist
- Exam section: Subscriber and Data Management
- Study guide: https://www.certifyforce.com/study-guide/marketing-cloud-engagement-specialist

**Official exam objective:**

> Given desired output requirements, set up Data Extensions in Marketing Cloud.

## What the exam expects

- Choose the data retention option (Individual Records, All records, All records and data extensions) and a period or date from what must disappear and when.
- Build a triggered send source data extension from its template and set its retention, knowing the default and what retention never deletes.
- Share one data extension with chosen business units through a shared data extensions folder.
- Link data extensions in Data Designer with matching data types, the right cardinality and the Contact Key.
- Key terms: **retention policy** (automatic deletion at the end of a period or on a date); **Triggered Send Source template** (the data extension template for triggered send sources); **shared data extension folder** (where a data extension is stored to share it across business units); **attribute group** (data extensions linked to the contact in Data Designer); **cardinality** (how linked records relate: one-to-one, one-to-many, many-to-many).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Individual Records | Rows deleted by creation date; table kept | [Create a Data Extension](https://help.salesforce.com/s/articleView?id=sf.mc_es_create_data_extension.htm&language=en_US&type=5) |
| All records and data extensions | Rows and table deleted | [Create a Data Extension](https://help.salesforce.com/s/articleView?id=sf.mc_es_create_data_extension.htm&language=en_US&type=5) |
| Retention period | Specific date or time period | [Create a Data Extension](https://help.salesforce.com/s/articleView?id=sf.mc_es_create_data_extension.htm&language=en_US&type=5) |
| Triggered send source | Built from the Triggered Send Source template; one row per recipient per call | [Triggered Emails](https://help.salesforce.com/s/articleView?id=mc_es_triggered_emails.htm&language=en_US&type=5) |
| Triggered send retention | 1 day to forever; default 6 months; subscriber data kept | [Triggered Emails](https://help.salesforce.com/s/articleView?id=mc_es_triggered_emails.htm&language=en_US&type=5) |
| Sharing | Shared data extension folders; choose business units | [Data Extensions and Segmentation](https://trailhead.salesforce.com/content/learn/modules/marketing-cloud-contact-management/learn-about-data-extensions) |
| Lists in Enterprise 2.0 | Can't be shared | [List vs. Data Extension](https://help.salesforce.com/s/articleView?id=mc_es_list_versus_data_extension.htm&language=en_US&type=5) |
| Link fields | Must be the same data type | [Build Your Data Model](https://trailhead.salesforce.com/content/learn/modules/marketing-cloud-data-management/build-your-data-model) |
| Link key | Contact Key, not email, when available | [Configure Contact Data Models](https://trailhead.salesforce.com/content/learn/modules/marketing-cloud-contact-management/configure-contact-models) |
| Rows per contact | Rows past the 1,000th aren't evaluated | [Linked Data Extensions](https://help.salesforce.com/s/articleView?id=sf.mc_jb_data_relationships.htm&language=en_US&type=5) |

## Check yourself

- Why does Help advise an intermediate data extension for a many-to-many relationship in a journey?
- When does a contact's linked row stop being used for journey evaluation?
- Why can a triggering API call fail against a triggered send source?
- How many email triggered send definitions can one business unit create in 7 days, counting transactional send definitions?

## Sources

- [Create a Data Extension in Email Studio](https://help.salesforce.com/s/articleView?id=sf.mc_es_create_data_extension.htm&language=en_US&type=5)
- [Triggered Emails in Email Studio](https://help.salesforce.com/s/articleView?id=mc_es_triggered_emails.htm&language=en_US&type=5)
- [Data Extensions and Segmentation](https://trailhead.salesforce.com/content/learn/modules/marketing-cloud-contact-management/learn-about-data-extensions)
- [Email Studio List vs. Email Studio Data Extension](https://help.salesforce.com/s/articleView?id=mc_es_list_versus_data_extension.htm&language=en_US&type=5)
- [Build Your Data Model - Data Sources and Extensions](https://trailhead.salesforce.com/content/learn/modules/marketing-cloud-data-management/build-your-data-model)
- [Configure Contact Data Models](https://trailhead.salesforce.com/content/learn/modules/marketing-cloud-contact-management/configure-contact-models)
- [Linked Data Extensions in Journey Builder](https://help.salesforce.com/s/articleView?id=sf.mc_jb_data_relationships.htm&language=en_US&type=5)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 7 linked practice questions, and unlimited timed mock exams are included with the Marketing Cloud Engagement Specialist pack (USD $19): https://www.certifyforce.com/practice-exams