Choosing Which ServiceNow Tables You See
A ServiceNow archive contains far more tables than most organisations ever use. A stock instance ships hundreds of configuration-item classes and custom tables, and in a typical archive most of them are empty. Left alone, Cortex would list every browsable table in the mirror on the Browse and Search pages.
The Table Visibility tab of the ServiceNow data source editor controls that list. The settings apply to everyone who uses the data source, not per user, so agree on the list before widening or narrowing it.
Show only tables that are likely to be wanted
Show only tables that are likely to be wanted is on by default, so a ServiceNow archive shows the shortened list as soon as it is connected.
Cortex then keeps the standard ITSM tables plus any table that actually holds data in this archive. Clearing the checkbox shows every browsable table again.
Some points worth knowing:
- "Likely to be wanted" is worked out from the archive itself rather than from a fixed list, so it adapts to each instance: Cortex asks the mirror which tables currently hold at least one row.
- Tables that gain rows in a later migration appear in the list once the data source is refreshed.
- The curated ITSM tables are always kept, even when they are empty, so a freshly created archive that has not been populated yet still lists
incident,problemandchange_request. - The row check only ever removes tables it can prove are empty. If the check cannot run - a table that cannot be read, or a mirror that is unavailable - the tables are treated as populated and the filter quietly does nothing, rather than hiding data that is there.
Limit the visible tables to one group
Limit the visible tables to one group is optional and off by default. Choose a single group when you only want part of the instance listed:
| Group | What it contains |
|---|---|
| All tables | No narrowing. |
| Likely wanted | The curated standard tables plus any table that holds data. |
| ITSM Core | The day-to-day ITSM tables. |
| Platform metadata | ServiceNow's own configuration and metadata tables. |
| CMDB / Assets | Configuration-item and asset classes. |
| Knowledge | Knowledge base tables. |
| Service Catalog | Catalog item and request tables. |
| Custom / Extension | Custom tables, including u_* tables. |
This setting combines with the checkbox above: when both are set, a table must satisfy both to be listed. Setting a group on its own (with the checkbox cleared) lists that group's tables regardless of whether they hold data.
Override the visible table list
Override visible table list is off by default, and is independent of the two settings above - either can be used on its own. Turn it on to name tables individually:
| Setting | Effect |
|---|---|
| Only show these tables (leave empty to show all) | An allow list. When it has entries, only those tables are listed. |
| Hide these tables | A deny list. Those tables are dropped from the list. |
| Always show these tables (even if otherwise excluded) | Surfaces these tables whatever else is configured. |
A table on the Always show list is listed regardless of the other two, which is how you keep one table visible when it would otherwise be excluded by a group or by the allow list.
What the list does not restrict
The Table Visibility settings change which tables are listed. They do not restrict access to a record you reach another way: a record opened from a link or from a related list still opens, even when its table is not in the list.
See also
- ServiceNow Table-Per-Hierarchy (TPH) Mirrors - how Cortex stores and resolves ServiceNow's shared physical tables.
- Data Sources - managing connections inside Cortex.
- Getting Your ServiceNow Data - building the archive the data source reads.