Custom Table Deep Dive: Import Set Row

[Jake Gillespie]

As discussed in my previous article Custom Tables: Where and when to build, Import Set Tables are one of the most common types of tables created in the Now Platform. In this article, we'll deep dive into their purpose, usage, and how they fit into the Custom Table family.

Custom Table Disclaimer

The creation and usage of custom tables is directly tied to ServiceNow subscription entitlements. The articles I've written in relation to custom tables are based on the ServiceNow Custom Table Guide, which is available via the Legal Schedules -> Entitlement Supplements page. I strongly recommend seeking guidance from the ServiceNow Accounts team as licensing rules, entitlement SKUs, and specific limits can change over time. At the time of writing, this version became effective October 17, 2025.

What Are Import Set Tables?
In essence, an Import Set Table serves as a dedicated staging area for when data is loaded into the ServiceNow instance, whether during data migration or integration processes. When you import large volumes of external data from another system (e.g., a legacy database or a third-party API), that raw data should not be mapped directly into your permanent, operational tables like Incident [incident] or User [sys_user] (also known as Target Tables). Doing so would skip the opportunity to validate and/or adjust the data before it enters the database. It also doesn't allow for the fact that some of those target columns could be references to other records, meaning they hold Sys ID (aka guid) values that only apply in your ServiceNow instance. By using an Import Set Table we not only hold the staging data for 7 days, but also leverage a Transform Map process to handle such local record lookups.

Technically speaking, these tables are extended from the Import Set Row [sys_import_set_row] table. This structure allows ServiceNow to capture the raw data exactly as it arrives, including all its original fields and values, before any transformation or business logic is applied. The process typically involves three stages:

1. The raw data is loaded into the Import Set table.
2. A Transform Map processes this raw data according to defined rules.
3. The transformed data is moved into the Target Table for permanent storage.

Why Are They Exempt?
The distinction between Non-Exempt and Exempt tables is one of the most critical concepts when designing custom solutions in ServiceNow. While creating new custom tables consumes your subscription entitlements, as per the ServiceNow Custom Table Guide, Import Set tables are classified as Exempt Tables. This exemption status means that they do not count against your overall Custom Table usage limit.

This architectural decision reflects their intended purpose: they are temporary structures used to facilitate the data import lifecycle rather than serving as permanent repositories for core business information. They exist solely to bridge the gap between external, raw data and the structured, governed data within your instance.

When Should You Use Them?
You should utilise Import Set Tables whenever you need to ingest data from an external source that requires a transformation layer before it can be utilised by standard ServiceNow processes. Whether you are performing a one-time migration of historical records or setting up a continuous integration pipeline, the Import Set Table provides the necessary buffer and structure for reliable data handling.

By understanding the function and licensing status of Import Set Tables, we can design robust, scalable, and compliant data ingestion strategies within our ServiceNow environments.