afv-library/skills/omnistudio-datamapper-generate/references/best-practices.md

Data Mapper Best Practices

When to Use Each Type

Extract

Use Extract when:

• Reading data from one or more related Salesforce objects
• You need relationship queries (parent-to-child or child-to-parent)
• Formula fields are required in the output
• Data volume is moderate (under 10K records per execution)
• You need aggregate functions or complex filter logic

Do NOT use Extract when:

• Read volume exceeds 10K records consistently -- use Turbo Extract
• No SOQL is needed (data reshaping only) -- use Transform
• You are writing data -- use Load

Turbo Extract

Use Turbo Extract when:

• Read-heavy scenarios with high volume (10K+ records)
• Query is straightforward with indexed filter fields
• Formula fields are not required
• No related list (child-to-parent) queries are needed
• Performance is the primary concern (10x+ faster than standard Extract)

Do NOT use Turbo Extract when:

• Formula fields are needed in output
• Related list queries are required
• Aggregate queries (COUNT, SUM) are needed
• Polymorphic lookup fields are involved

Transform

Use Transform when:

• Reshaping JSON structures between Integration Procedure steps
• Renaming fields from one schema to another
• Flattening nested data structures
• Filtering or merging in-memory datasets
• No database interaction is needed

Do NOT use Transform when:

• Reading from or writing to Salesforce objects -- use Extract or Load
• Data needs to be persisted -- use Load

Load

Use Load when:

• Inserting, updating, upserting, or deleting Salesforce records
• Writing data collected from OmniScript input or external sources
• Synchronizing data from Integration Procedure callout responses

Do NOT use Load when:

• Reading data -- use Extract or Turbo Extract
• Reshaping data without persistence -- use Transform

---

Field Mapping Patterns

Explicit Field Selection

Always specify fields explicitly. Never rely on wildcard or "all fields" selection.

Good:  Account.Name, Account.Industry, Account.BillingCity
Bad:   Account.* (extracts all fields, wastes bandwidth and heap)

Input/Output Path Structure

Data Mapper fields use dot-notation paths for input and output:

Input Path:   AccountData.Name
Output Path:  Account.Name

For nested structures:

Input Path:   Response.data.accounts[0].name
Output Path:  AccountList.Name

Type Conversion Handling

Map fields with compatible types. Common conversions:

Source Type	Target Type	Notes
String	Date	Requires ISO 8601 format (YYYY-MM-DD)
String	Number	Ensure source contains numeric values only
Boolean	String	Maps to "true"/"false" string literals
DateTime	Date	Truncates time component
Picklist	String	Maps selected value as string

Lookup Resolution for Load

When loading records with lookup relationships:

1. Define a lookup mapping that resolves the external key to a Salesforce ID
2. Specify the lookup object and match field (e.g., Account.Name to resolve AccountId)
3. Handle cases where the lookup returns no match (set default or fail gracefully)

Field:         AccountId
Lookup Object: Account
Match Field:   Name
Input Path:    InputData.AccountName

---

Query Sequence Optimization

Filter Field Indexing

For Extract and Turbo Extract, filter on indexed fields whenever possible:

• Id (always indexed)
• Name (indexed on standard objects)
• CreatedDate (indexed)
• SystemModstamp (indexed)
• Custom fields marked as External ID or Unique
• Custom Index fields (request from admin if needed)

Filter Order

Place the most selective filter first to reduce the result set early:

Good:  WHERE Id = :recordId AND Status = 'Active'
Bad:   WHERE Status = 'Active' AND Id = :recordId

Relationship Query Depth

Limit relationship traversal to 2 levels for performance:

Good:  Account.Owner.Name (1 level)
Bad:   Account.Parent.Parent.Parent.Owner.Name (3+ levels)

Limit and Offset

Always set a LIMIT on Extract queries unless the consuming component guarantees a bounded input:

LIMIT 200    -- Standard batch size
LIMIT 2000   -- Maximum for most UI scenarios
LIMIT 10000  -- Absolute maximum, use only with pagination

---

Null Handling and Type Conversion

Default Values

Set default values for fields that may be null to prevent downstream errors:

Field Type	Recommended Default	Rationale
String	"" (empty string)	Prevents null reference in concatenation
Number	0	Prevents null arithmetic errors
Boolean	false	Prevents null conditional evaluation
Date	(no default)	Leave null; do not fabricate dates
Lookup	(no default)	Leave null; handle in consuming component

Null-Safe Mapping

When mapping fields that may be null:

1. Set isNullable: true on the OmniDataTransformItem
2. Configure a default value where business logic requires one
3. Document which fields are expected to be null in certain scenarios
4. Test with records that have null values in mapped fields

---

Relationship Queries

Parent-to-Child (Subquery)

Extract supports parent-to-child relationship queries:

Object: Account
Fields: Name, Industry
Child Relationship: Contacts (Contact)
Child Fields: FirstName, LastName, Email

Output structure:

{
  "Name": "Acme Corp",
  "Industry": "Technology",
  "Contacts": [
    { "FirstName": "Jane", "LastName": "Doe", "Email": "jane@acme.com" }
  ]
}

Child-to-Parent (Lookup Traversal)

Extract supports child-to-parent traversal via dot notation:

Object: Contact
Fields: FirstName, LastName, Account.Name, Account.Industry

Output structure:

{
  "FirstName": "Jane",
  "LastName": "Doe",
  "AccountName": "Acme Corp",
  "AccountIndustry": "Technology"
}

Turbo Extract Limitations

Turbo Extract does NOT support:

• Child-to-parent relationship queries (subqueries)
• Formula fields
• Aggregate functions
• Polymorphic lookups (e.g., WhoId on Task)

---

Performance with Large Data Volumes

Batch Size Recommendations

Record Count	Recommended Approach
1-200	Standard Extract, single call
200-2000	Turbo Extract, single call
2000-10000	Turbo Extract with pagination via Integration Procedure
10000+	Batch processing: scheduled Integration Procedure with chunked Turbo Extract calls

Heap Size Management

Each Data Mapper execution contributes to the Apex heap limit (6 MB synchronous, 12 MB async):

• Map only the fields you need (reduces JSON payload size)
• Use Turbo Extract for large result sets (server-side processing reduces heap usage)
• Paginate results when total data exceeds 2 MB

Caching Strategy

For data that changes infrequently:

• Enable Platform Cache in the consuming Integration Procedure
• Set appropriate TTL (Time To Live) based on data change frequency
• Cache at the org partition level for shared reference data
• Cache at the session partition level for user-specific data

Monitoring

Track Data Mapper performance using:

sf data query -q "SELECT Id,Name,Type,LastModifiedDate FROM OmniDataTransform WHERE IsActive=true ORDER BY LastModifiedDate DESC" -o <org>

Review execution logs in OmniStudio Designer > Data Mapper > Preview to identify slow queries and excessive field counts.