The correct choice is to add a condition using `current.changesField('state')` to the Business Rule, because this directly optimizes business rule performance by adding a condition to run only when the relevant field changes. Without this guard, the GlideAggregate executes on every update to the incident table, wasting database cycles on unnecessary record counts. On the ServiceNow Certified Application Developer CAD exam, this scenario tests your understanding of declarative performance optimization—specifically, how to prevent heavy server-side scripts from firing on irrelevant updates. A common trap is choosing to move the logic to a different table or to cache the aggregate result, but those either shift the problem or risk stale data. The key insight is that `changesField()` evaluates only the current transaction, making it a lightweight filter that preserves functionality exactly when needed. Memory tip: think “change the field, change the load”—if the field hasn’t changed, the script shouldn’t load the database.
SNOW-CAD Core Application Development Practice Question
This SNOW-CAD practice question tests your understanding of core application development. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer is optimizing a Business Rule that runs on every update to the 'incident' table. The rule uses GlideAggregate to count related records. The developer notices performance degradation. Which change will most improve performance while maintaining functionality?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a condition to the Business Rule such as 'current.changesField('state')' to only run the aggregate when relevant.
Option C is correct because it prevents the GlideAggregate from executing on every update, instead running only when the 'state' field changes. This reduces unnecessary database operations, directly addressing the performance degradation while preserving the rule's functionality when needed.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Replace GlideAggregate with GlideRecord and count results manually.
Why it's wrong here
GlideRecord would be slower than GlideAggregate for counting.
✗
Add a database index on the foreign key field used in the aggregate.
Why it's wrong here
Indexing helps but is not a script change; the question asks for a change to the script.
✓
Add a condition to the Business Rule such as 'current.changesField('state')' to only run the aggregate when relevant.
Why this is correct
Limiting execution to only when the 'state' field changes reduces unnecessary processing.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the gs.addInfoMessage() to log the count and disable the script in production.
Why it's wrong here
Logging does not reduce processing; disabling would break functionality.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ServiceNow often tests the misconception that adding an index (Option B) is the universal performance fix, but the trap here is that reducing unnecessary execution (Option C) is a more impactful optimization than improving query speed for a query that runs too often.
Detailed technical explanation
How to think about this question
GlideAggregate executes a SQL COUNT query on the database server, which is efficient for counting but still incurs overhead on every update. The Business Rule condition 'current.changesField('state')' leverages the GlideRecord 'changesField' method, which checks the 'sys_updated' field's previous and current values without an additional query. In a real-world scenario, a Business Rule on a high-volume table like 'incident' can cause significant slowdowns if it runs on every update, especially when the aggregate involves large related tables.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the SNOW-CAD exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Core Application Development — This question tests Core Application Development — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a condition to the Business Rule such as 'current.changesField('state')' to only run the aggregate when relevant. — Option C is correct because it prevents the GlideAggregate from executing on every update, instead running only when the 'state' field changes. This reduces unnecessary database operations, directly addressing the performance degradation while preserving the rule's functionality when needed.
What should I do if I get this SNOW-CAD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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