Semantic sources, source systems and logical models

Every Warehouse table belongs to at least one logical model. Dimension, Fact and Dictionary tables also use a source system, and each source system sits inside a semantic source. Create these objects before you create your tables, and come back here when you need to edit or remove one.

• A semantic source is a named group of source systems. It shows where the data of your tables comes from.
• A source system is one upstream data origin inside a semantic source.
• A logical model is a business grouping of tables. It defines core entities and their relationships.

Create a semantic source and a source system

1. In the Warehouse tree toolbar, click New > Semantic source. You can also click Add New in the Warehouse header and choose Semantic source under Sources & logical models. The Warehouse workspace tour covers the tree and its toolbar.
2. In the Semantic sources window, click Add.
3. Fill in Source Name and Description, then click Create. You see the message "Semantic Source registered successfully".
4. Select the semantic source and click Add system in its header.
5. Fill in System Name and Description, then click Create. You see the message "Source System registered successfully".

Create a logical model

1. In the Warehouse tree toolbar, click New > Logical model. You can also choose Logical model under Sources & logical models in Add New.
2. In the models window, click Add Model.
3. Fill in Model Name and Description, then click Create. You see the message "Logical Model registered successfully".

The models window, its cards and the edit and delete flows are described on Logical models.

Add a table to a source system

1. Open the options menu of the source system row, or right-click the source system in the tree.
2. Under Add table, in the row menu, choose Dimension, Fact or Dictionary. In the tree, the same choices sit under Add.
3. The new table opens with that source system already selected.

Explore the Semantic sources window

The window shows the searchable list of sources on the left, and the selected source with its source systems on the right.

• Search sources and systems… finds both. While you search, matching sources are grouped under Semantic sources and matching systems under Source systems; choosing a result clears the search and selects it. A source matches on its name or its description, and a system matches on its own name or description only, never on the name of its source.
• The header of the selected source shows its description and three counts: Systems, Tables and Transformations. The counts add up the rows below: Systems counts the source systems, Tables counts their tables and Dictionary queries, and Transformations counts the transformations that read from them.
• The systems table lists Name, Description, Tables and Transformations for each system, sorted A to Z. Use Filter systems… to narrow it; the badge next to the heading shows the total, or "N found" while you filter.
• Click a system row to expand it: the row shows Loading tables linked to followed by the system's name, then lists its tables and their transformations. Click one to open it in its own popup. When some are left out, the row says for example "3 transformations on tables not shown here." A system nothing points at yet says "No tables use this system yet." Opening another source closes the rows you had open.
• When the window opens from a chat message or a tree row that points at one source system, it selects that system's source and highlights the system.

While the window loads it shows Loading semantic sources; when it cannot load, it shows Semantic sources did not load with a Try again button that reloads the list.

Edit a semantic source or a source system

1. Choose the object to change:
   • For a semantic source, select it and click Edit.
   • For a source system, open its options menu and choose Edit.
   • For a logical model, edit it from its card; see Logical models.
2. Change the Description. The name field is locked.
3. Click Save Changes. The button stays greyed out until you change something in the form, and shows Saving... while it saves.

A saved edit is confirmed with a message such as "Semantic Source updated successfully" or "Source System updated successfully".

Delete a semantic source, source system or logical model

Delete from the bottom up, because a semantic source cannot be deleted while it still has source systems:

1. Delete the tables and transformations that use a source system, or point them at another source system with Batch edit. To delete tables, see Deploy, run, truncate and monitor tables.
2. Open the source system's options menu, choose Delete, then confirm in the Confirm Deletion dialog. You see the message "Source System deleted successfully".
3. Select the semantic source, click Delete in its header, then confirm with Delete. You see the message "Semantic Source deleted successfully".

A logical model is deleted from its card in the models window, and only while no table uses it; see Logical models. For the general delete flow in the tree, including batch deletion and retrying objects that fail to delete, see Delete Warehouse objects.

Who can change these objects

If your role lacks the permission, the change is refused with an access-denied message that names the missing permission. For the presets and how they combine, see Warehouse permissions and row-level security.

Settings and rules

Limits and edge cases

• A source system belongs to one semantic source only.
• A semantic source with source systems cannot be deleted. Its Delete button stays greyed out and shows the reason, for example "Remove its 2 source systems first."
• A source system still used by tables, Dictionary queries or transformations cannot be deleted. Its Delete item stays greyed out, and the menu shows the reason, for example "Used by 3 tables and 1 transformation."
• Removing a source system from a table is refused while that system has data in the Warehouse. Truncate that data first.
• A name that already exists is refused. You see "The Semantic Source with the name your name already exists", "The Source System with the name your name already exists" or "The model with the your name already exists."
• Source systems apply to Dimension, Fact and Dictionary tables. Views and Static tables do not use source systems.

Questions, answered

Why can't I type a longer source system name?

Source system names are limited to 15 characters. Keep the name short and put the detail in the Description.

Why is Delete greyed out on a source system?

A table or transformation still uses it. The menu shows the counts under the greyed item, for example "Used by 2 tables and 1 transformation". Delete or change those tables and transformations first, then delete the source system.

How do I delete a semantic source?

Delete its source systems first. The Delete button stays greyed out until the semantic source has none. Then select it, click Delete, and confirm.

Can I rename a semantic source, source system or logical model?

Not from the edit form: the name field is locked once the object exists, and only the description can change. For a source system that has loaded data there is a second reason: the rows it brings in carry its name as the Source System ID, so a rename would fork the data of one system into two names. To use a different name, create a new object, move the tables to it with Batch edit, and delete the old one.

Do I have to write a description?

Yes. The form requires a description of 20 to 500 characters for all three objects.

Can a Static table belong to a source system?

No. The Static editor has no source system field, and the Add table menu offers only Dimension, Fact and Dictionary. A Static table still needs at least one logical model.

Can one table belong to several logical models?

Yes. A Dimension or Fact table can have up to 20 logical models. Select them under Logical Models when you configure the table. See Create a dimension or fact table.

How do I see which tables use a source system?

Click the source system row in the semantic source window. The row expands to list the tables and transformations that use it. Click one to open it. If nothing uses the system, the row says "No tables use this system yet."

Can I change many tables of one source system at once?

Yes. Open the source system's options menu and choose Batch edit tables. See Batch edit.

How do I find a source system without knowing its parent source?

Type into Search sources and systems… in the Semantic sources window. Matching systems are listed under Source systems, and each one shows the name of its source on the right. A system matches on its own name or description only, so searching for a source's name does not list all of its systems. Choosing a result selects it and clears the search.

What do the numbers at the top of a semantic source mean?

Systems counts the source systems in the list below. Tables adds up the Tables column of those rows, which counts tables and Dictionary queries, and Transformations adds up their transformations.

How do I see what changed recently?

In a chat with the Warehouse Builder Mind, ask what changed in a window, such as "What changed in the Warehouse since 1 October?" It lists the semantic sources, source systems, logical models and other Warehouse objects that were created or updated in that window, newest first, and you can ask it to show one person's changes. Give the start of the window; the end defaults to now, and it must be later than the start. It returns up to 50 objects by default, and at most 200 at once. Warehouse Builder Minds are visible to the admin role only; see Warehouse Builder and Lake Builder.