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

# Preview transformation result

> Executes the provided SQL in DuckDB (in-memory) with the delta extension loaded and returns the first N rows (default 50) plus column types.



## OpenAPI

````yaml /api-reference/catalog-api.json post /transformations/preview
openapi: 3.1.0
info:
  title: Strattum Catalog API
  description: Expõe a estrutura do data lake — camadas, conectores e tabelas.
  version: 0.1.0
servers: []
security: []
paths:
  /transformations/preview:
    post:
      tags:
        - transformations
      summary: Preview transformation result
      description: >-
        Executes the provided SQL in DuckDB (in-memory) with the delta extension
        loaded and returns the first N rows (default 50) plus column types.
      operationId: preview_transformation_transformations_preview_post
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/PreviewRequest'
        required: true
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PreviewResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
components:
  schemas:
    PreviewRequest:
      properties:
        sql:
          type: string
          title: Sql
        limit:
          type: integer
          title: Limit
          default: 50
      type: object
      required:
        - sql
      title: PreviewRequest
    PreviewResponse:
      properties:
        columns:
          items:
            additionalProperties: true
            type: object
          type: array
          title: Columns
        rows:
          items:
            additionalProperties: true
            type: object
          type: array
          title: Rows
        total_rows:
          anyOf:
            - type: integer
            - type: 'null'
          title: Total Rows
        error:
          anyOf:
            - type: string
            - type: 'null'
          title: Error
      type: object
      required:
        - columns
        - rows
      title: PreviewResponse
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError

````