---
title: "Merge insert (upsert) records into a table"
method: POST
path: "/v1/table/{id}/merge_insert"
tags: ["Table"]
---

# Merge insert (upsert) records into a table

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

Performs a merge insert (upsert) operation on a table. This operation updates existing rows based on a matching column and inserts new rows that don't match. Returns the number of rows inserted and updated.

## Path parameters

- `id` string, required

## Query parameters

- `on` string, required
- `when_matched_update_all` boolean
- `when_not_matched_insert_all` boolean

## Response `200`

Result of merge insert operation

- MergeInsertTableResponse — Response from merge insert operation
  - `num_updated_rows` integer — Number of rows updated
  - `num_inserted_rows` integer — Number of rows inserted
  - `num_deleted_rows` integer — Number of rows deleted (typically 0 for merge insert)
  - `version` integer — The commit version associated with the operation

## 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

- **2025-07-21** `6790486d1fac` — 7 breaking, 21 warning, 22 info
  - removed the media type `application/vnd.apache.arrow.stream` from the request body
  - removed the required property `code` from the response with the `400` status
  - removed the required property `code` from the response with the `401` status
  - removed the required property `code` from the response with the `403` status
  - …46 more

[Change history](https://skmtc.dev/lance-format/apis/lance-namespace-specification/changes/v1/table/:id/merge_insert/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/6790486d1fac/schema)