SF-Data-Arch Large Data Volume Considerations Practice Question
Exhibit
LIMIT 50000 SELECT Id FROM Custom_Object__c WHERE Status__c = 'Pending' // Result: Query Exception: Non-selective query against large object
Refer to the exhibit. What is the most likely reason this query fails?
⚠ Common exam trap
Candidates frequently assume a field is indexed by default, failing to account for the selectivity threshold, where even an indexed field can cause failure if too many records match.
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 field 'Status__c' is not indexed.
The query fails because 'Status__c' is likely not indexed, or the 'Pending' value is too common, exceeding the selectivity threshold. On objects with millions of records, Salesforce requires that filters target a small enough subset to be efficient. When a filter is too broad or lacks an index, the system rejects the query to prevent performance degradation for the entire multi-tenant environment.
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 LIMIT clause is too high for the object size.
Why it's wrong here
The LIMIT clause restricts the number of records returned but does not affect the query's ability to locate those records. A query can be highly selective and still request 50,000 records. The error indicates the engine cannot find the records efficiently, not that it is returning too many.
- ✓
The field 'Status__c' is not indexed.
Why this is correct
Without an index on the 'Status__c' field, the database must perform a full table scan to evaluate every record. Since the object contains millions of records, this exceeds the system's threshold for selectivity, causing the query to fail to protect overall system performance and availability.
- ✗
The query includes too many fields in the SELECT clause.
Why it's wrong here
Including more fields in a SELECT statement does not impact the selectivity of a query. The database engine performance is based on the filtering criteria in the WHERE clause, not the number of columns retrieved, provided that the filtering is efficient enough to locate the records.
- ✗
The record count exceeds the object storage limit.
Why it's wrong here
Object storage limits pertain to the total amount of data allowed in the org, not the ability to query specific records. A query error regarding selectivity is strictly about the query execution plan and the efficiency of data retrieval, not the total volume of stored data.
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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
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