---
title: "Entities Explained"
url: "https://docs.noreja.com/en/article/entities-explained"
language: "en"
last_updated: "2026-10-23T08:26:38.014Z"
---

# Entities Explained

What an entity is, how its objects and data connections turn the tables of a data source into activities and cases, and what a valid entity needs, with the Purchase-to-Pay example.

An entity tells Noreja how the tables of a data source fit together: which rows are events of the process, when they happened, and which rows of different tables belong together. The data specialist sets up an entity once; process analysts then build perspectives on top of it without needing to know the tables. This page explains what an entity consists of, with the Purchase-to-Pay example. Older material calls entities "entity-graph"; it's the same thing.

### From Data Source to Perspective

In the Builder, the three menu items build on each other:

-   **Sources**: the connection to a database or system, for example the data source "Demo" with the purchasing tables.
-   **Entities**: which tables are used, as which events, and how they are connected. Each entity belongs to exactly one data source, which can't be changed later. A data source can have several entities.
-   **Perspective**: the view on a process, built on an entity, with the expected order of the activities. Each perspective uses one entity; one entity can carry several perspectives, and each of them uses only the activities it needs. A perspective on invoice processing, for example, can leave out the order activities that a perspective on the whole purchasing process includes.

![Diagram: the tables dbo.bestellung, dbo.bestellposition and dbo.zahlung of the data source become the objects Bestellung erstellt (one row = one order), bestellposition angelegt (one row = one item) and zahlung innerhalb skontofrist (one row = one payment, only rows with skonto_genutzt = 'ja'), which become activities of the perspective](https://cdn-assets.productfruits.com/62775a52-de5e-4ae7-a538-f91ab4e0e1d4)

The Purchase-to-Pay entity uses the tables of the data source "Demo". It has 24 objects, linked by 23 data connections:

![The Purchase-to-Pay entity in the Builder: on the left the tables of the data source with how often each is used, on the right the 24 objects as a tree, for example Bestellung erstellt in the middle with the order items, the invoice and the purchase requisition around it](https://cdn-assets.productfruits.com/939fbc68-6e44-428e-a1c5-5bc1c2d4a8ff)

### Objects: One Kind of Event

An object is a table of the data source that you place in the entity. It describes one kind of event, and each object becomes one activity: in perspectives and in the Analyzer it appears under its **Activity name**. Every row the object reads is one execution of that activity, with its own time stamp.

A table can be used for several objects, each reading only some of its rows. In Purchase-to-Pay, the payment table dbo.zahlung gives three objects: "Zahlung ausgeführt", "zahlung innerhalb skontofrist" and "zahlung außerhalb skontofrist". "zahlung innerhalb skontofrist", for example, reads only the payments made within the discount period. In the list of tables, the numbers after each table show how often it is used: dbo.bestellung (3/5) is used by three objects, which have five data connections between them and to other objects.

Right-click an object and choose **Configure** to open its settings (**Configure object**):

![Configure object for zahlung innerhalb skontofrist from the table dbo.zahlung: Activity name, Start timestamp zahlung_ausgefuehrt_am, an empty Change timestamp, the Unique identifier with zahlung_id selected, and under Advanced queries the WHERE clause skonto_genutzt = 'ja'](https://cdn-assets.productfruits.com/15c27aa7-41be-4b8f-8bf9-c84e620b8659)

| Setting | What it does |
| --- | --- |
| **Activity name** | The name of the activity in perspectives and the Analyzer. It must be unique within the entity and can have up to 100 characters. |
| **Start timestamp** | Required: the date and time column that says when the event happened. All times in the Analyzer are calculated from it. |
| **Change timestamp** | Optional: when the event was changed, for example a later correction of an order. It's only used if it lies after the start time stamp. |
| **Properties** | The columns that come along with each execution, for example amounts or a status. They appear in the Analyzer's details and can be used for filters. |
| **Unique identifier** | The columns that together identify one event, by default the table's primary key. If the selected columns don't identify each row uniquely, different events get the same identifier and can't be told apart. |
| **Advanced queries** | The **WHERE clause** limits which rows the object reads, as for zahlung innerhalb skontofrist above. The **JOIN clause** adds columns of other tables as properties, for example supplier data to an order. |

An object counts as configured once its query has run without errors: **Confirm** tests it and saves it, **Save draft** keeps it unfinished. Unconfigured objects are highlighted on the canvas, and the entity can't be imported until every object is configured. See [Configure Objects and Relationships](https://docs.noreja.com/en/article/configuring-an-entity).

The same menu has **Context**: knowledge about this activity for Minerva, for example what a manual clarification means and when it's needed. See [Context Hub: Knowledge for Minerva](https://docs.noreja.com/en/article/contextualizing-knowledge-for-minerva-ai).

### Data Connections: Which Rows Belong Together

A data connection links two objects. It says which rows of the one belong to which rows of the other, by mapping columns with the same value, like a join in a database. Right-click the line between two objects and choose **Configure** to open **Configure data connection**:

![Configure data connection from Bestellung erstellt (dbo.bestellung) to bestellposition angelegt (dbo.bestellposition): under With mapping, the column bestellung_id of the item table is mapped to bestellung_id of the order table](https://cdn-assets.productfruits.com/b95155ca-515f-4853-95e9-c1cb65cf581b)

-   **Mapped field**: which column of the one table matches which column of the other. Here, an item belongs to the order with the same bestellung\\\_id.
-   **Cross table**: a table in between, for tables that have no column in common.
-   **With condition**: an extra condition for the match.

One row can match several rows on the other side: an order with three items is linked to all three. This is where the numbers and cardinalities in the process graph come from; see [Quantities and Cardinalities](https://docs.noreja.com/en/article/deep-dive-cardinalities). The direction of the arrow doesn't matter for the process: the expected order of the activities is set in the perspective.

### How Cases Come Together

Which rows form one case is decided in the perspective: the process analyst chooses the object whose identifier is the case ID, for example the order; see [Create a Perspective](https://docs.noreja.com/en/article/crafting-a-dimension-causal-hypothesis). Noreja then collects, for each case, the executions that can be reached from that object along the data connections. That's why every object has to be connected to the others.

### What a Valid Entity Needs

-   At least two objects.
-   All objects connected into one network, without separate groups. Otherwise the import stops with *Each entity graph needs to be a connected graph.*
-   Every object and data connection configured. Otherwise the import names the one that isn't, for example *Activity … is not configured*.
-   For every object, a start time stamp and at least one column in the unique identifier.

We recommend arranging the objects as a star or a tree, as in Purchase-to-Pay: then every object is reached from the case object on exactly one route, which keeps cases easy to follow. Noreja also accepts closed loops of data connections, but the route between two objects is then no longer unique. See [Entity Modelling Best Practices](https://docs.noreja.com/en/article/entity-modelling-best-practices).

### Own Object or Property?

Make a table its own object if it records an event with its own time stamp, such as an order, a goods receipt or a payment. Tables without their own events, such as suppliers or materials, are better added to an object as properties with the JOIN clause; see [Use Joined Properties](https://docs.noreja.com/en/article/use-joined-properties). In Purchase-to-Pay, the tables dbo.lieferant and dbo.material are selected but not used as objects (0/0).

### Importing

Importing an entity reads the data from the source: one step per object and per data connection, then **Import model**. Importing a perspective then works on this imported data and doesn't read the source again. The **Entities** list shows for each entity whether it is imported and how the last import went. See [Import Entities and Perspectives: Status and Errors](https://docs.noreja.com/en/article/import-entities-and-perspectives-status-and-errors).

### Related

-   [Create an Entity, Manually or with Suggestions](https://docs.noreja.com/en/article/create-an-entity-manually-or-with-suggestions)
-   [Configure Objects and Relationships](https://docs.noreja.com/en/article/configuring-an-entity)
-   [Entity Modelling Best Practices](https://docs.noreja.com/en/article/entity-modelling-best-practices)
-   [Create a Perspective](https://docs.noreja.com/en/article/crafting-a-dimension-causal-hypothesis)
-   [Quantities and Cardinalities](https://docs.noreja.com/en/article/deep-dive-cardinalities)