> ## Documentation Index > Fetch the complete documentation index at: https://docs.cognite.com/llms.txt > Use this file to discover all available pages before exploring further. # About data modeling modes > Learn about additive and rebuild modes for deploying data model changes with NEAT. Understand when to use each mode. NEAT supports two data modeling modes: additive and rebuild. Deployment behavior in Cognite Data Fusion (CDF) depends on which mode you use. Changes are classified into three severity levels: * **SAFE**: No impact on existing data or functionality * **WARNING**: Allowed with caution (changes may have implications, for example, adding a constraint can cause ingestion pipelines to fail if they don't comply with the constraint) * **BREAKING**: Not applied to CDF ## Why it matters Choosing the right mode protects your data and applications. Additive mode is intended for production environments where stability is crucial, while rebuild mode is designed for development/sandbox environments where you can iterate quickly delete and recreate models so you try out and do breaking changes. Rebuild is not suitable for production because it deletes the containers and data, which can lead to data loss. The sections below describe each mode and list the allowed and disallowed changes per severity level. NEAT considers only changes to data model components (DMS schema components) in the same space as the data model. Changes outside that space are ignored to prevent accidental modifications to data models owned or managed by other teams. ## Additive mode Additive mode provides: * **Forward compatibility**: Existing applications work with the updated model without changes. * **Incremental deployment**: Changes apply gradually for controlled evolution. * **Production suitability**: Best for production environments where stability and forward compatibility matter. The table below lists allowed and disallowed changes in additive mode: | Severity | Operation | Change description | Example | | ------------ | --------- | -------------------------------------------------- | ------------------------------------------------------------ | | **SAFE** | Create | Data model | - | | **SAFE** | Create | View | Entire views, new properties, filters | | **SAFE** | Create | Container | Entire containers, new properties, indexes and constraints | | **SAFE** | Create | New enums to existing enum properties | - | | **SAFE** | Update | Data model metadata | Name, description, version | | **SAFE** | Update | Data model's view order | - | | **SAFE** | Update | View metadata | Name, description, version | | **SAFE** | Update | Container metadata | Name, description | | **SAFE** | Update | Property metadata | Name, description | | **SAFE** | Update | Enums metadata | Name, description | | **WARNING** | Update | View filters | - | | **WARNING** | Update | Edge type | - | | **WARNING** | Update | Source property for reverse connection | Also known as `through` in CDF API | | **WARNING** | Remove | Container constraints | - | | **WARNING** | Remove | Container indexes | - | | **WARNING** | Update | Mutability of container properties | - | | **WARNING** | Update | Auto-increment of container properties | - | | **WARNING** | Update | Default value of container properties | - | | **WARNING** | Update | Max count of listable properties | - | | **WARNING** | Remove | Container property unit | Removing `meter` from a property | | **WARNING** | Add | Container property unit | Adding `meter` to a property that did not have a unit before | | **BREAKING** | Delete | Existing data model | - | | **BREAKING** | Delete | View reference from the data model | - | | **BREAKING** | Delete | Existing view | - | | **BREAKING** | Add | Implements to an existing view | - | | **BREAKING** | Delete | Property from an existing view | - | | **BREAKING** | Update | Mapping of view (property) to container (property) | - | | **BREAKING** | Update | Direct/reverse connection value type | Also known as `source` in CDF API | | **BREAKING** | Update | Edge source of properties | Setting new view as source of properties | | **BREAKING** | Update | Edge direction | - | | **BREAKING** | Update | Connection type | From edge to direct connection | | **BREAKING** | Update | What container is used for | Switching `usedFor` from `node` to `edge` | | **BREAKING** | Update | Value type of container property | From `text` to `integer` | | **BREAKING** | Update | Container constraint definitions | `uniqueness` constraint property `bySpace` cannot be changed | | **BREAKING** | Update | Container index definitions | Adding or removing properties to which the index applies | | **BREAKING** | Update | Nullability of container properties | - | | **BREAKING** | Update | Container property unit | Changing from `meter` to `kilometer` | | **BREAKING** | Update | `maxTextSize` of text properties | - | | **BREAKING** | Delete | Enum values from existing enum properties | - | ## Rebuild mode Rebuild mode allows every change because the entire model is deleted and recreated. Use it for development or testing where no existing data or applications depend on the model. Deployment fails if containers contain data—NEAT does not remove data accidentally. To delete existing data intentionally, set `drop_data=True` when deploying: `neat.physical_data_model.write.cdf(dry_run=False, drop_data=True)`. ## Further reading * [Install NEAT](/cdf/deploy/neat/installation) — Set up NEAT and deploy your first data model * [Data modeling principles](/cdf/deploy/neat/data_modeling/principles) — Best practices for designing data models with NEAT