> For the complete documentation index, see [llms.txt](https://specs.govstack.global/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://specs.govstack.global/registries/development/7-data-structures.md).

# 7 Data Structures

## 7.1 Resource Model

The resource model shows the relationship between data objects that are used by this Building Block.

{% @mermaid/diagram content="erDiagram
DATABASE||--o{ DATA: has
DATABASE {
int id
varchar name
json schema
numeric version   }
DATA ||--|{ AUDIT-LOG: creates
DATA {
int id
varchar registry-number
varchar field-type
varchar value
}
AUDIT-LOG {
varchar old-value
varchar new-value    }
DATABASE ||--|{ SCHEMA: has
SCHEMA {
int id
varchar path    }
SCHEMA ||--|{ DATA: contains" %}

## 7.2 Data Structures <a href="#docs-internal-guid-f4ace18b-7fff-ada5-ebbb-3aaf5e08cb17" id="docs-internal-guid-f4ace18b-7fff-ada5-ebbb-3aaf5e08cb17"></a>

The Data Structures provide detail for the Resource Model defined above. This section will list the core/required fields for each resource.

### 7.2.1 Minimum Required Data

**Description:** The Data Structures can be extended for a particular use case, but they must always contain, at the minimum, the fields defined here.

**Fields:**

<table><thead><tr><th>Name</th><th>Type</th><th>Description</th><th>Notes</th><th data-hidden></th></tr></thead><tbody><tr><td>Database ID</td><td>integer</td><td>Unique identifier of a database.</td><td>Required</td><td></td></tr><tr><td>Database name</td><td>varchar</td><td>Name that will define the database content. Name is public.</td><td>Required</td><td></td></tr><tr><td>Schema ID</td><td>integer</td><td>Database schema ID</td><td>Required</td><td></td></tr><tr><td>Database schema</td><td>json object</td><td>Database schema. See example in Chapters 7.3.1 and 7.3.2.</td><td>Required</td><td></td></tr><tr><td>Version</td><td>numeric</td><td>Database version. Each change in schema will produce the next version of the database and API services.</td><td>Required</td><td></td></tr><tr><td>Data ID</td><td>integer</td><td>Data element unique identifier.</td><td>Required</td><td></td></tr><tr><td>Registry number</td><td>varchar</td><td>Additional registry identifier. Unique identifier in the registry.</td><td>Required</td><td></td></tr><tr><td>Field type</td><td>varchar</td><td>Field type: datetime, date, boolean, text, number, file.</td><td>Required</td><td></td></tr><tr><td>Field value</td><td>datetime, date, boolean, text, number</td><td>Field value, data stored in the field.</td><td>Required</td><td></td></tr><tr><td>Audit log old value</td><td>datetime, date, boolean, text, number</td><td>Field value before change.</td><td>Required</td><td></td></tr><tr><td>Audit log new value</td><td>datetime, date, boolean, text, number</td><td>Field value after the change.</td><td>Required</td><td></td></tr></tbody></table>


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