Adding custom sys_schema_attribute records
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yesterday
Hello,
I'm interested in managing custom application behaviour via custom table attributes.
I know this can just be done by editing the sys_dictionary.attributes field directly but I would like to improve maintainability for future developers/maintainers by instead adding an entry to sys_schema_attribute and using sys_schema_attribute_m2m entries, same as you'd see for OOTB attributes.
When creating a sys_schema_attribute record the above message shows:
"Schema attributes are a predefined set of elements that alter the behavior of the table or column they are applied to. New attributes cannot be created, but administrators can add or remove most attributes from the schema elements to which they are applied. More Info"
The More Info link doesn't go anywhere useful and the "New attributes cannot be created" message is clearly false.
My question is:
1) What is the purpose of this message?
2) Are there any reasons not to create "sys_schema_attribute" records, from what I can tell all it would do is provide context to any custom table/field attributes. What's the downside?
Apologies if this is the incorrect forum, unsure where to post such a general platform development question.
Thank you
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31m ago
Hi @ChristopherV430 ,
The message “New attributes cannot be created” is a bit misleading. It’s really a guardrail from ServiceNow to discourage admins from extending sys_schema_attribute in ways that aren’t officially supported. Schema attributes are meant to be a predefined set of behaviors that the platform itself recognizes (things like auto_number, can_read, etc.). The banner is there to remind you that these attributes are system‑defined and not guaranteed to work if you add your own.
Technically, you can create new records in sys_schema_attribute, and they’ll show up in the Admin Console and link via sys_schema_attribute_m2m. But the downsides are worth noting:
- They may not be recognized by all platform tooling (Studio, schema maps, automated testing).
- They could break or be ignored in future upgrades.
- ServiceNow Support may flag them as “unsupported customization.”
- Future developers might assume your custom attribute is out‑of‑the‑box and expect platform‑level behavior when it’s really just metadata you added.
If your goal is maintainability, the safer approach is either:
- Stick with sys_dictionary.attributes and document your custom flags clearly, or
- Create a separate custom metadata table to store application‑specific attributes. That way you get structured context without touching unsupported internals.
