> ## Documentation Index > Fetch the complete documentation index at: https://dify-6c0370d8-fix-template-upload-size-guidance.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Create Child Chunk > Create a child chunk under a parent chunk. Intended for documents that use the parent-child (`hierarchical_model`) chunking mode. ## OpenAPI ````yaml /en/api-reference/openapi_service.json post /datasets/{dataset_id}/documents/{document_id}/segments/{segment_id}/child_chunks openapi: 3.0.1 info: description: >- REST API for Dify applications and knowledge bases. Application endpoints authenticate with an app API key; knowledge endpoints authenticate with a dataset API key. title: Dify Service API version: 1.0.0 servers: - description: >- Base URL of the Dify Service API. For self-hosted deployments, replace it with your own API base URL. url: https://{api_base_url} variables: api_base_url: default: api.dify.ai/v1 description: Host and path of the API base URL, without the `https://` prefix. security: - ApiKeyAuth: [] tags: - description: Operations related to chat messages and interactions. name: Chat Messages - description: File upload and preview operations. name: Files - description: Operations related to end user information. name: End Users - description: User feedback operations. name: Feedback - description: Operations related to managing conversations. name: Conversations - description: Text-to-Speech and Speech-to-Text operations. name: Audio - description: Operations to retrieve application settings and information. name: Applications - description: Operations related to managing annotations for direct replies. name: Annotations - description: Endpoints for resuming paused workflows that require human input. name: Human Input - description: Operations for executing and managing workflows. name: Workflow Runs - description: Operations related to text generation and completion. name: Completion Messages - description: >- Operations for managing knowledge bases, including creation, configuration, and retrieval. name: Knowledge Bases - description: >- Operations for creating, updating, and managing documents within a knowledge base. name: Documents - description: Operations for managing document chunks and child chunks. name: Chunks - description: >- Operations for managing knowledge base metadata fields and document metadata values. name: Metadata - description: Operations for managing knowledge base tags and tag bindings. name: Tags - description: Operations for retrieving available models. name: Models - description: >- Operations for managing and running knowledge pipelines, including datasource plugins and pipeline execution. name: Knowledge Pipeline paths: /datasets/{dataset_id}/documents/{document_id}/segments/{segment_id}/child_chunks: post: tags: - Chunks summary: Create Child Chunk description: >- Create a child chunk under a parent chunk. Intended for documents that use the parent-child (`hierarchical_model`) chunking mode. operationId: createChildChunk parameters: - description: >- Knowledge base ID. Obtain it from [List Knowledge Bases](/en/api-reference/knowledge-bases/list-knowledge-bases). in: path name: dataset_id required: true schema: format: uuid type: string - description: >- Document ID. Obtain it from [List Documents](/en/api-reference/documents/list-documents). in: path name: document_id required: true schema: format: uuid type: string - description: >- Parent chunk ID. Obtain it from [List Chunks](/en/api-reference/chunks/list-chunks). in: path name: segment_id required: true schema: format: uuid type: string requestBody: content: application/json: schema: properties: content: description: Child chunk text content. type: string required: - content type: object required: true responses: '200': content: application/json: examples: success: summary: Response Example value: data: content: Dify is an open-source platform. created_at: 1741267200 id: d7e8f9a0-1b2c-3d4e-5f6a-7b8c9d0e1f2a position: 1 segment_id: f3d1c7be-9f3a-40d8-8eb8-3a1ef9c3f2c1 type: customized updated_at: 1741267200 word_count: 6 schema: properties: data: $ref: '#/components/schemas/ChildChunk' type: object description: Child chunk created successfully. '400': content: application/json: examples: invalid_param: summary: invalid_param value: code: invalid_param message: >- Vector store operation failed: [Errno 111] Connection refused status: 400 provider_not_initialize: summary: provider_not_initialize value: code: provider_not_initialize message: >- No Embedding Model available. Please configure a valid provider in the Settings -> Model Provider. status: 400 description: >- - `provider_not_initialize` : The knowledge base uses high-quality indexing but its embedding model is missing or misconfigured. - `invalid_param` : Indexing the child chunk in the vector store failed; the message carries the underlying vector-store error. '403': content: application/json: examples: forbidden_1: summary: forbidden (api access) value: code: forbidden message: Dataset api access is not enabled. status: 403 forbidden_2: summary: forbidden (vector space) value: code: forbidden message: >- The capacity of the vector space has reached the limit of your subscription. status: 403 forbidden_3: summary: forbidden (rate limit) value: code: forbidden message: >- Sorry, you have reached the knowledge base request rate limit of your subscription. status: 403 forbidden_4: summary: forbidden (upgrade plan) value: code: forbidden message: >- To unlock this feature and elevate your Dify experience, please upgrade to a paid plan. status: 403 description: >- - `forbidden` : Dataset api access is not enabled. - `forbidden` : The capacity of the vector space has reached the limit of your subscription. - `forbidden` : Sorry, you have reached the knowledge base request rate limit of your subscription. - `forbidden` : To unlock this feature and elevate your Dify experience, please upgrade to a paid plan. '404': content: application/json: examples: not_found_1: summary: not_found value: code: not_found message: Dataset not found. status: 404 not_found_2: summary: not_found value: code: not_found message: Document not found. status: 404 not_found_3: summary: not_found value: code: not_found message: Segment not found. status: 404 description: |- - `not_found` : Dataset not found. - `not_found` : Document not found. - `not_found` : Segment not found. '503': content: application/json: examples: service_unavailable: summary: service_unavailable value: code: service_unavailable message: >- Unable to verify vector space usage right now. Please try again later. status: 503 description: >- `service_unavailable` : Vector space usage could not be verified. Returned on the Dify Cloud Sandbox plan only; retry the request later. components: schemas: ChildChunk: properties: content: description: Text content of the child chunk. type: string created_at: description: Creation timestamp (Unix epoch in seconds). type: number id: description: Unique identifier of the child chunk. type: string position: description: Position of the child chunk within the parent chunk. type: integer segment_id: description: ID of the parent chunk this child chunk belongs to. type: string type: description: >- How the child chunk was created. Child chunks created or updated through the API are always `customized`. System-generated child chunks are `automatic`. type: string updated_at: description: Last update timestamp (Unix epoch in seconds). type: number word_count: description: Word count of the child chunk content. type: integer type: object securitySchemes: ApiKeyAuth: bearerFormat: API_KEY description: >- Every request authenticates with an API key: `Authorization: Bearer {API_KEY}`. App endpoints take an app API key; knowledge endpoints take a knowledge base API key ([Get Started](/en/api-reference/guides/get-started)). Keep keys server-side; never embed them in client code. Requests with a missing or invalid key fail with HTTP `401` (`unauthorized`). scheme: bearer type: http ````