Sys_Id: retain existing or generate new during data migration?

[Chenlin]

Hi,

I'm seeking for a guideline on sys_id handling:

When migrating data from one system to another, in general should record sys_id be copied to new system, or let the new system to generate new ids?
Note that it's between two different systems, rather than different instances (e.g. Dev, QA, UAT, Stage, etc.) of the same system.

I was from SQL server background and in that domain it was strongly suggested to leave it to the platform for performance consideration (so that guid are generated sequentially), but it seems ServiceNow platform might not have the same constraint.

Please advice,

Thanks!

[Sandeep Rajput · Accepted solution]

@Chenlin You can choose to retain the previous sys_ids if

1. There are parent child relationships among records

2. When any external system store your existing sys_id as correlation id in their tables

3. When any update set refers to the sys_ids of these records.

You can choose to generate new sys_ids if

1.There is no dependency on the original sys_ids(no parent child relationships)

2. No external system stores your sys_id

From performance stand point, there is no impact as sys_id is a 32 character unique string and it will remain unique even if it is migrated to a different instance. 

[Ankur Bawiskar]

@Chenlin 

From my experience and understanding even if there is a new sysId there won't be any impact.

SysIds are unique and generated within the platform when record is inserted.

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

[Chenlin]

Thank you all!