Indexing Fields in Servicenow

[Madhan007]

Hi Everyone,

We are planning to Index the following fields.
1. Custom Corelation ID field on Security Incident [sn_si_incident] Table.

2.Employment Number field on HR Profile Table

3.Code field on Cost Center Table

4.Custom field on a Group table

5.Custom field on a core Table

Note : All these fields are being used as Coalesce fields in Transform maps

I want to learn a few things about Indexing -
1. will there be any impact if the field is Indexed ?
2.How much time does it take to index a field for a table and will there be any performance issues on the Instance while indexing a field ?

3.Will there be any impact on Transform Maps ( since these fields are being used as Coelasce)?
4.Can we move Indexing changes on Update sets ?

Please pour your Insights.

Thanks in Advance!!

[Ankur Bawiskar]

@Madhan007 

-> A unique index should be checked when the business requirement requires that values in the indexed field (or combination of fields) are never duplicated in the table. This enforces data integrity—if uniqueness is not needed, leave it unchecked to avoid errors during inserts or updates.

-> if it's get captured in update set then please validate it after moving update set.

If my response helped please mark it correct and close the thread so that it benefits future readers.

[Madhan007]

@Ankur Bawiskar , if a field coming from parent table is marked as Index in child table, does it impact parent table and other child tables ?

[Ankur Bawiskar]

@Madhan007 

Nope, it impacts only child table

💡 If my response helped, please mark it as correct ✔️ and close the thread 🔒 — this helps future readers find the solution faster! 🙏

[nityabans27]

Hi @Madhan007,

My thoughts->

If you find them helpful please accept as solution.

Question Insight / Recommendation

1. Impact of indexing a field	Generally positive for query/search performance, especially for Coalesce fields. Minimal negative impact; some extra storage and slightly slower inserts/updates due to index maintenance.
2. Time to index & performance during indexing	Time depends on table size; small tables take seconds–minutes, large tables may take longer. Index creation can briefly consume DB resources, but ServiceNow handles it safely. For huge tables, consider scheduling during off-peak hours.
3. Impact on Transform Maps (Coalesce fields)	No functional impact; indexing does not change Coalesce behavior. Actually improves lookup performance during transforms.
4. Can indexing changes be moved via Update Sets?	No. Indexes are database-level changes; they cannot be moved through Update Sets. Must be created manually in the target instance or via database scripts approved by admin.

[Madhan007]

Hey @nityabans27 , Thanks for your reply

I verified that Indexing changes are captured in the update set