# Virtualized data with Salesforce Connect external objects

*Platform Data Architect Study Guide · Large Data Volume Considerations · Last updated October 26, 2026 · https://www.certifyforce.com/study-guide/platform-data-architect/large-data-volume-considerations/virtualized-data-with-salesforce-connect-external-objects*

When to read external data on demand instead of copying it, which Salesforce Connect adapter fits, how external objects relate to other records and authenticate, what they can't do in reports, fields and queries, and the other virtualization options: Files Connect, Heroku Connect and Data 360 zero copy.

- Certification: Salesforce Platform Data Architect
- Exam section: Large Data Volume Considerations
- Study guide: https://www.certifyforce.com/study-guide/platform-data-architect

**Official exam objective:**

> Given a customer scenario, decide when to use virtualized data and describe virtualized data options.

## What the exam expects

- Decide when to virtualize instead of copying, from volume, freshness, residency and how much data users read at once.
- Pick the Salesforce Connect adapter and include its add-on licence in the design.
- Relate external data with lookup, external lookup and indirect lookup relationships, and secure it with per-user authentication.
- Predict where external objects fall short: field types, reports, search sync, filters, activities.
- Name the other options: Files Connect, Heroku Connect and Data 360 (formerly Data Cloud) zero copy data federation.

Key terms: **external object** (maps to a table in an external system; API name ends `__x`); **external data source** (connection details and adapter); **external lookup** (child matched to an external parent's External ID standard field); **indirect lookup** (external child matched to a unique External ID on a Salesforce parent); **zero copy data federation** (Data 360 reads external warehouse data without copying it).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Licensing | Extra cost in Enterprise, Performance, Unlimited; included in Developer Edition | [Salesforce Connect](https://help.salesforce.com/s/articleView?language=en_US&id=sf.platform_connect_about.htm&type=5) |
| External objects per org | Up to 200 (default may be 100, raised by support case); don't count toward custom objects | [Define External Objects](https://help.salesforce.com/s/articleView?language=en_US&id=platform.external_object_define.htm&type=5), [Connect Limits](https://help.salesforce.com/s/articleView?id=sf.platform_connect_general_limits.htm&language=en_US&type=5) |
| Report rows | Up to 20,000 primary-object records | [Connect Reports](https://help.salesforce.com/s/articleView?id=platform.platform_connect_considerations_reports.htm&language=en_US&type=5) |
| Empty-string filter | Converted to a null filter | [Connect Limits](https://help.salesforce.com/s/articleView?id=sf.platform_connect_general_limits.htm&language=en_US&type=5) |
| Cross-org API usage | Each callout counts toward the provider org's API limits | [Connect Limits](https://help.salesforce.com/s/articleView?id=sf.platform_connect_general_limits.htm&language=en_US&type=5) |
| Picklist fields | Only with the cross-org adapter | [External Objects](https://help.salesforce.com/s/articleView?id=platform.platform_connect_considerations_compatibility.htm&language=en_US&type=5) |
| Validator | Tests ID uniqueness, sorting and filtering | [External Data Sources](https://help.salesforce.com/s/articleView?id=platform.external_data_sources.htm&language=en_US&type=5) |
| Composite keys | No external or indirect lookups to them | [External Object Relationships](https://help.salesforce.com/s/articleView?id=platform.external_object_relationships.htm&language=en_US&type=5) |

## Check yourself

- Why must a SOQL filter on an external text field sometimes include spaces the page doesn't show?
- When does a flow need a zero-second Pause before creating an external object record?
- Which report features don't work with external objects?
- Why choose Files Connect rather than Salesforce Connect for contract PDFs?

## Sources

- [Salesforce Connect](https://help.salesforce.com/s/articleView?language=en_US&id=sf.platform_connect_about.htm&type=5)
- [Choose Which Salesforce Connect Adapter to Use](https://help.salesforce.com/s/articleView?language=en_US&id=platform.platform_connect_adapters.htm&type=5)
- [Data Virtualization (Integration Patterns)](https://developer.salesforce.com/docs/atlas.en-us.integration_patterns_and_practices.meta/integration_patterns_and_practices/integ_pat_data_virtualization.htm)
- [External Objects in Salesforce Connect](https://help.salesforce.com/s/articleView?id=platform.platform_connect_considerations_compatibility.htm&language=en_US&type=5)
- [External Object Relationships](https://help.salesforce.com/s/articleView?id=platform.external_object_relationships.htm&language=en_US&type=5)
- [Work with External Data Sources](https://help.salesforce.com/s/articleView?id=platform.external_data_sources.htm&language=en_US&type=5)
- [Define External Objects](https://help.salesforce.com/s/articleView?language=en_US&id=platform.external_object_define.htm&type=5)
- [Salesforce Connect Support for Reports](https://help.salesforce.com/s/articleView?id=platform.platform_connect_considerations_reports.htm&language=en_US&type=5)
- [General Limits for Salesforce Connect](https://help.salesforce.com/s/articleView?id=sf.platform_connect_general_limits.htm&language=en_US&type=5)
- [Salesforce Platform Features Supported by Salesforce Connect](https://help.salesforce.com/s/articleView?id=platform.platform_connect_considerations.htm&language=en_US&type=5)
- [Data Integration Decision Guide](https://architect.salesforce.com/docs/architect/decision-guides/guide/data-integration.html)
- [Trailhead: Get Started with Zero Copy Data Federation](https://trailhead.salesforce.com/content/learn/modules/data-cloud-with-zero-copy/get-started-with-zero-copy-data-federation)
- [Connect External Objects to Your Salesforce Org](https://help.salesforce.com/s/articleView?id=sf.connect_external_objects.htm&language=en_US&type=5)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 20 linked practice questions, and unlimited timed mock exams are included with the Platform Data Architect pack (USD $19): https://www.certifyforce.com/practice-exams