1. Introduction

This document describes how ServiceNow upgrade affects SnowMirror.

It contains a list of database schema changes made by ServiceNow from one ServiceNow release to another. We have created the list by comparing two clean developer instances. Tables of inactive plugins were not compared.

2. Compatibility

Every SnowMirror installation supports multiple ServiceNow releases. When a new ServiceNow is released, we tweak SnowMirror to support it. At the same time, SnowMirror stays compatible with previous ServiceNow releases. Even if you don’t want to upgrade your ServiceNow yet, you can upgrade SnowMirror to the latest version.

3. Step-By-Step Guide

  1. Upgrade SnowMirror to an appropriate version before you upgrade ServiceNow.

  2. Familiarize yourself with how potential schema changes affect your SnowMirror.

  3. Upgrade ServiceNow.

  4. Synchronizations running during the upgrade may fail.

    1. Go to Settings → ServiceNow page and click "Save" to cleanup and re-initialize all connections to ServiceNow.

    2. Manually re-run failed synchronizations or wait until SnowMirror runs them according to their schedule.

4. How ServiceNow Upgrade Affects SnowMirror

Before a new ServiceNow upgrade is released to public, we always make sure that SnowMirror works with it properly.

We recommend you to upgrade to the latest SnowMirror version before you upgrade your ServiceNow.

There may be differences in database schema between two ServiceNow releases. Depending on your Auto Schema Update settings we may reflect those changes into your mirror database.

  • New tables - If you want to synchronize new tables you have to create their respective synchronizations manually. You can see the list of new tables in Schema Changes chapter.

  • New columns - If Auto Schema Update is enabled new columns are automatically added to the mirror table. Clean synchronization is usually required, depending on your Auto Schema Update Settings.

  • Updated columns - Most updates can be applied to the mirror table without clearing all data. Some updates require us to clear the mirror table, make the change and synchronize from scratch.

    The decision whether to clear the table may be database server specific.

  • Deleted column - If Auto Schema Update is enabled SnowMirror deletes the columns from mirror database automatically.

Sometimes, you may see the same column being created and deleted at the same time. That happens when a column changes its SysId.

How can a column change its SysId, you may ask. ServiceNow may change the structure of tables and move columns from child table to parent table and vice versa. Because of the different SysIds, SnowMirror considers such columns as new ones. In case Auto Schema Update is enabled, SnowMirror downloads tables with such columns from scratch (i.e. Clean & Synchronize).

5. SnowMirror Support

ServiceNow Release SnowMirror Release SnowMirror Release Date


SnowMirror 5.7.0

March, 2024


SnowMirror 5.5.0

September, 2023


SnowMirror 5.1.0

March, 2023


SnowMirror 4.14.0

September, 2022

San Diego

SnowMirror 4.12.0

March, 2022


SnowMirror 4.11.0

September, 2021


SnowMirror 4.9.0

March, 2021


SnowMirror 4.8.0

August, 2020


SnowMirror 4.6.0

March, 2020

New York

SnowMirror 4.4.0

September 9, 2019


SnowMirror 4.3.0

April 16, 2019


SnowMirror 4.1.0

September 5, 2018

6. Schema Changes

This chapter contains a list of schema changes in ServiceNow releases.

We compared an old clean developer instance with a new clean developer instance. We did not activate any plugins. Therefore, tables created by plugins are not a part of the list.