SF-Data-Arch Large Data Volume Considerations Practice Question
A Salesforce org has a custom object Log__c with 5 million records. The object has a lookup to Case. Users report that when they view a Case record, the related list of Log__c records takes a long time to load. The data architect decides to create a custom index on the Case lookup field. After the index is created, performance improves. Which statement best explains why the index improved performance?
⚠ Common exam trap
The trap here is assuming that indexes improve performance by sorting or caching, when in fact their primary benefit is enabling fast, selective filtering.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The index allows the related list query to use an index to quickly retrieve Log__c records for the specific Case.
The related list on Case queries Log__c records filtered by the Case lookup. This filter is highly selective because it returns only records for one Case. Creating a custom index on the lookup field allows the query optimizer to use the index, avoiding a full table scan. Thus, the index directly improves the performance of the related list query.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The index reduces the number of records that need to be queried by pre-filtering the Log__c object.
Why it's wrong here
An index does not pre-filter records; it provides a fast lookup mechanism. The query still needs to evaluate the filter condition, but the index allows the database to quickly locate matching records without scanning the entire object. The reduction in query time is due to faster access, not a reduction in the number of records evaluated.
- ✓
The index allows the related list query to use an index to quickly retrieve Log__c records for the specific Case.
Why this is correct
When viewing a Case record, the related list of Log__c records is displayed by querying Log__c where Case__c equals the current Case Id. This filter is highly selective because it returns only the logs for one case. With a custom index on Case__c, the query optimizer can use the index to efficiently retrieve those records, significantly improving performance.
- ✗
The index enables the related list to be loaded from a cache instead of the database.
Why it's wrong here
Salesforce does use caching for some metadata and frequently accessed data, but a custom index does not directly cause related list data to be cached. The improvement is from the database using the index to execute the query more efficiently. Caching is a separate mechanism and not the primary reason for the performance gain here.
- ✗
The index sorts the Log__c records by Case, which speeds up the display order in the related list.
Why it's wrong here
Indexes are primarily used for filtering, not for sorting. While an index can sometimes help with sorting if it matches the ORDER BY clause, the related list typically does not require a specific sort order that would benefit from this index. The performance gain is due to faster filtering, not sorting.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Salesforce exam blueprint
This SF-Data-Arch practice question is part of Courseiva's free Salesforce certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SF-Data-Arch exam.