> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dify.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Create Child Chunk

> Create a child chunk under a parent chunk. Only available for documents using the `hierarchical_model` chunking mode.



## OpenAPI

````yaml /en/api-reference/openapi_knowledge.json post /datasets/{dataset_id}/documents/{document_id}/segments/{segment_id}/child_chunks
openapi: 3.0.1
info:
  title: Knowledge API
  description: >-
    API for managing knowledge bases, documents, chunks, metadata, and tags,
    including creation, retrieval, and configuration. **Note:** A single
    Knowledge Base API key has permission to operate on all visible knowledge
    bases under the same account. Please pay attention to data security.
  version: 1.0.0
servers:
  - url: '{apiBaseUrl}'
    description: The base URL for the Knowledge API.
    variables:
      apiBaseUrl:
        default: https://api.dify.ai/v1
        description: Actual base URL of the API
security:
  - ApiKeyAuth: []
tags:
  - name: Knowledge Bases
    description: >-
      Operations for managing knowledge bases, including creation,
      configuration, and retrieval.
  - name: Documents
    description: >-
      Operations for creating, updating, and managing documents within a
      knowledge base.
  - name: Chunks
    description: Operations for managing document chunks and child chunks.
  - name: Metadata
    description: >-
      Operations for managing knowledge base metadata fields and document
      metadata values.
  - name: Tags
    description: Operations for managing knowledge base tags and tag bindings.
  - name: Models
    description: Operations for retrieving available models.
  - name: Knowledge Pipeline
    description: >-
      Operations for managing and running knowledge pipelines, including
      datasource plugins and pipeline execution.
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. Only available for documents
        using the `hierarchical_model` chunking mode.
      operationId: createChildChunk
      parameters:
        - name: dataset_id
          in: path
          required: true
          schema:
            type: string
            format: uuid
          description: Knowledge base ID.
        - name: document_id
          in: path
          required: true
          schema:
            type: string
            format: uuid
          description: Document ID.
        - name: segment_id
          in: path
          required: true
          schema:
            type: string
            format: uuid
          description: Chunk ID.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - content
              properties:
                content:
                  type: string
                  description: Child chunk text content.
      responses:
        '200':
          description: Child chunk created successfully.
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    $ref: '#/components/schemas/ChildChunk'
              examples:
                success:
                  summary: Response Example
                  value:
                    data:
                      id: d7e8f9a0-1b2c-3d4e-5f6a-7b8c9d0e1f2a
                      segment_id: f3d1c7be-9f3a-40d8-8eb8-3a1ef9c3f2c1
                      content: Dify is an open-source platform.
                      position: 1
                      word_count: 6
                      type: automatic
                      created_at: 1741267200
                      updated_at: 1741267200
        '400':
          description: '`invalid_param` : Create child chunk index failed.'
          content:
            application/json:
              examples:
                invalid_param:
                  summary: invalid_param
                  value:
                    status: 400
                    code: invalid_param
                    message: 'Create child chunk index failed: {error details}'
components:
  schemas:
    ChildChunk:
      type: object
      properties:
        id:
          type: string
          description: Unique identifier of the child chunk.
        segment_id:
          type: string
          description: ID of the parent chunk this child chunk belongs to.
        content:
          type: string
          description: Text content of the child chunk.
        position:
          type: integer
          description: Position of the child chunk within the parent chunk.
        word_count:
          type: integer
          description: Word count of the child chunk content.
        type:
          type: string
          description: >-
            How the child chunk was created. `automatic` for system-generated,
            `custom` for manually created.
        created_at:
          type: number
          description: Creation timestamp (Unix epoch in seconds).
        updated_at:
          type: number
          description: Last update timestamp (Unix epoch in seconds).
  securitySchemes:
    ApiKeyAuth:
      type: http
      scheme: bearer
      bearerFormat: API_KEY
      description: >-
        API Key authentication. For all API requests, include your API Key in
        the `Authorization` HTTP Header, prefixed with `Bearer `. Example:
        `Authorization: Bearer {API_KEY}`. **Strongly recommend storing your API
        Key on the server-side, not shared or stored on the client-side, to
        avoid possible API-Key leakage that can lead to serious consequences.**

````