---
title: "Update per-field metadata"
method: POST
path: "/v1/table/{id}/update_field_metadata"
tags: ["Table", "Metadata"]
---

# Update per-field metadata

`POST /v1/table/{id}/update_field_metadata`

Update the Arrow field (column) metadata for table `id`.

Each entry targets a field by `path` and merges the provided key-value
pairs into that field's existing metadata, or replaces it when `replace`
is true. A null metadata value deletes that key.

## Path parameters

- `id` string, required

## Query parameters

- `delimiter` string

## Request body

- UpdateFieldMetadataRequest
  - `identity` Identity — Identity information of a request.
    - `api_key` string — API key for authentication. REST NAMESPACE ONLY This is passed via the `x-api-key` header.
    - `auth_token` string — Bearer token for authentication. REST NAMESPACE ONLY This is passed via the `Authorization` header with the Bearer scheme (e.g., `Bearer <token>`).
  - `context` unknown
  - `id` string[] — Table identifier path (namespace + table name)
  - `branch` string — Branch to target. When not specified, the main branch is used.
  - `updates` UpdateFieldMetadataEntry[], required — List of per-field metadata updates to apply
    - `path` string, required — Lance field path whose metadata to update. Nested fields use dot-separated segments; use backtick-quoted segments for literal dots and double backticks inside quoted segments. Use canonical full paths for display and errors; leaf names alone only identify top-level fields; invalid or unresolved paths should return InvalidInput or TableColumnNotFound.
    - `metadata` unknown, required
    - `replace` boolean, nullable — If true, replace the field's existing metadata entirely; otherwise merge into it (optional, defaults to false).

## Response `200`

Field metadata update result

- UpdateFieldMetadataResponse
  - `context` unknown
  - `version` integer, required — The commit version associated with the operation
  - `fields` unknown

## Other responses

- `400` — Indicates a bad request error. It could be caused by an unexpected request body format or other forms of request validation failure, such as invalid json. Usually serves application/json content, although in some cases simple text/plain content might be returned by the server's middleware.
- `401` — Unauthorized. The request lacks valid authentication credentials for the operation.
- `403` — Forbidden. Authenticated user does not have the necessary permissions.
- `404` — A server-side problem that means can not find the specified resource.
- `503` — The service is not ready to handle the request. The client should wait and retry. The service may additionally send a Retry-After header to indicate when to retry.
- `5XX` — A server-side problem that might not be addressable from the client side. Used for server 5xx errors without more specific documentation in individual routes.

## Changes

> 54 revisions in range; 2 could not be searched.

- **2026-07-01** `591cd95574b0` — 8 info
  - added the new optional request property `context`
  - added the optional property `context` to the response with the `200` status
  - added the optional property `context` to the response with the `400` status
  - added the optional property `context` to the response with the `401` status
  - …4 more
- **2026-06-10** `a3308034a3cd` — 1 breaking
  - the `updates/items/path` request property's minLength was increased from `0` to `1`
- **2026-06-05** `9932582b6bd7` — 1 info
  - added the new optional request property `branch`
- **2026-06-02** `1f753d169284` — 1 info
  - endpoint added
- **2025-07-21** `6790486d1fac` — 1 breaking
  - api path removed without deprecation

[Change history](https://skmtc.dev/lance-format/apis/lance-namespace-specification/changes/v1/table/:id/update_field_metadata/post.md)

---

[API](https://skmtc.dev/lance-format/apis/lance-namespace-specification.md) · [All operations](https://skmtc.dev/lance-format/apis/lance-namespace-specification/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/lance-format/lance-namespace-specification/revisions/541331733d0c/schema)