# Data Mapper query design and caching

*Omnistudio Consultant Study Guide · Data Mappers · Last updated October 27, 2026 · https://www.certifyforce.com/study-guide/omnistudio-consultant/data-mappers/data-mapper-query-design-and-caching*

How to cut Data Mapper queries with relationship notation, step order and IN filters, keep filters on indexed fields and objects to three or fewer, page within the OFFSET limit, and choose Session or Org data caching and metadata caching.

- Certification: Salesforce Omnistudio Consultant
- Exam section: Data Mappers
- Study guide: https://www.certifyforce.com/study-guide/omnistudio-consultant

**Official exam objective:**

> Describe the techniques to optimize Data Mapper performance, such as reducing the number of queries, efficient filtering, relationship queries, caching, and avoiding unnecessary data mapping.

## What the exam expects

- Recommend relationship notation for parent fields and an extra extract step only for child records.
- Explain how an Extract chains queries per returned record, and redesign a step order that risks the SOQL limit.
- Recommend fewer objects per Data Mapper, indexed filters and sorts, and one IN-filtered call instead of one call per record.
- Explain LIMIT and OFFSET paging and the OFFSET ceiling.
- Choose Session Cache or Org Cache and a valid Time To Live, and explain metadata caching with Scale Cache or Platform Cache.

Key terms: **relationship notation** (a parent field path such as `Account.Name` in the same query); **extract step** (one object queried by an Extract); **data cache** (a stored Data Mapper response); **Time To Live In Minutes** (how long cached data stays); **metadata cache** (the stored Data Mapper definition).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Relationship direction | Child-to-parent only | [Relationship Notation versus Multiple Extract Steps](https://help.salesforce.com/s/articleView?id=xcloud.os_relationship_notation_versus_multiple_extract_steps_45995.htm&language=en_US&type=5) |
| Parent fields | One step with notation: one query instead of two | [Relationship Notation versus Multiple Extract Steps](https://help.salesforce.com/s/articleView?id=xcloud.os_relationship_notation_versus_multiple_extract_steps_45995.htm&language=en_US&type=5) |
| Child records | At least two extract steps | [When to Use Multiple Extract Steps](https://help.salesforce.com/s/articleView?id=xcloud.os_when_to_use_multiple_extract_steps_45967.htm&language=en_US&type=5) |
| SOQL limit | 100 per Apex transaction; exceeding it fails the Data Mapper | [Configure an Omnistudio Data Mapper Extract](https://help.salesforce.com/s/articleView?id=xcloud.os_define_the_initial_extraction_45906.htm&language=en_US&type=5) |
| Objects per Data Mapper | Three or fewer | [Omnistudio Data Mapper Best Practices](https://help.salesforce.com/s/articleView?language=en_US&id=xcloud.os_dataraptor_best_practices_47412.htm&type=5) |
| Filters and ORDER BY | On indexed fields; Id and Name always indexed | [Omnistudio Data Mapper Best Practices](https://help.salesforce.com/s/articleView?language=en_US&id=xcloud.os_dataraptor_best_practices_47412.htm&type=5) |
| LIMIT | 1 through 50000; default 50000 | [Configure an Omnistudio Data Mapper Extract](https://help.salesforce.com/s/articleView?id=xcloud.os_define_the_initial_extraction_45906.htm&language=en_US&type=5) |
| OFFSET | Dynamic input node; 0 to 2000 | [Configure an Omnistudio Data Mapper Extract](https://help.salesforce.com/s/articleView?id=xcloud.os_define_the_initial_extraction_45906.htm&language=en_US&type=5) |
| Cacheable types | Extract, Turbo Extract, Transform (Options tab) | [Improving Data Mapper Performance with Caching](https://help.salesforce.com/s/articleView?id=xcloud.os_cache_for_dataraptors_and_integration_procedures_48057.htm&language=en_US&type=5) |
| Time To Live | Minimum 5; Session max 480; Org default 1440, max 2880 | [Configure Caching for a Data Mapper](https://help.salesforce.com/s/articleView?id=xcloud.os_configure_caching_for_data_mappers.htm&language=en_US&type=5) |
| Metadata with Platform Cache | Allocate space in the VlocityMetadata partition | [Improving Data Mapper Performance with Caching](https://help.salesforce.com/s/articleView?id=xcloud.os_cache_for_dataraptors_and_integration_procedures_48057.htm&language=en_US&type=5) |

## Check yourself

- Why does a parent field need only relationship notation while child records need another extract step on Standard Runtime?
- When can a two-step Extract fail even though each query is small?
- Which cache type and maximum Time To Live suit user-specific Data Mapper results on Standard Runtime?
- When must an admin allocate the VlocityMetadata partition?

## Sources

- [Omnistudio Data Mapper Best Practices](https://help.salesforce.com/s/articleView?language=en_US&id=xcloud.os_dataraptor_best_practices_47412.htm&type=5)
- [Relationship Notation versus Multiple Extract Steps](https://help.salesforce.com/s/articleView?id=xcloud.os_relationship_notation_versus_multiple_extract_steps_45995.htm&language=en_US&type=5)
- [When to Use Multiple Extract Steps](https://help.salesforce.com/s/articleView?id=xcloud.os_when_to_use_multiple_extract_steps_45967.htm&language=en_US&type=5)
- [Designing Data Mappers for Optimal Performance](https://trailhead.salesforce.com/content/learn/modules/omnistudio-data-mapper-fundamentals/design-data-mappers-for-performance)
- [Configure an Omnistudio Data Mapper Extract](https://help.salesforce.com/s/articleView?id=xcloud.os_define_the_initial_extraction_45906.htm&language=en_US&type=5)
- [Configure a Data Mapper Turbo Extract](https://help.salesforce.com/s/articleView?id=xcloud.os_configure_a_dataraptor_turbo_extract_45667.htm&language=en_US&type=5)
- [Improving Data Mapper Performance with Caching](https://help.salesforce.com/s/articleView?id=xcloud.os_cache_for_dataraptors_and_integration_procedures_48057.htm&language=en_US&type=5)
- [Configure Caching for a Data Mapper](https://help.salesforce.com/s/articleView?id=xcloud.os_configure_caching_for_data_mappers.htm&language=en_US&type=5)
- [Map Inputs and Outputs for Transformations](https://help.salesforce.com/s/articleView?id=xcloud.os_dataraptor_transform_data_mappings_46630.htm&language=en_US&type=5)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 10 linked practice questions, and unlimited timed mock exams are included with the Omnistudio Consultant pack (USD $19): https://www.certifyforce.com/practice-exams