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

# Merge insert (upsert) records into a table

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

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

REST NAMESPACE ONLY
REST namespace uses Arrow IPC stream as the request body.
It passes in the `MergeInsertIntoTableRequest` information in the following way:
- `id`: pass through path parameter of the same name
- `on`: pass through query parameter of the same name
- `when_matched_update_all`: pass through query parameter of the same name
- `when_matched_update_all_filt`: pass through query parameter of the same name
- `when_not_matched_insert_all`: pass through query parameter of the same name
- `when_not_matched_by_source_delete`: pass through query parameter of the same name
- `when_not_matched_by_source_delete_filt`: pass through query parameter of the same name

## Path parameters

- `id` string, required

## Query parameters

- `delimiter` string, nullable — An opaque token that allows pagination for list operations (e.g. ListNamespaces). For an initial request of a list operation, if the implementation cannot return all items in one response, or if there are more items than the page limit specified in the request, the implementation must return a page token in the response, indicating there are more results available. After the initial request, the value of the page token from each response must be used as the page token value for the next request. Caller must interpret either `null`, missing value or empty string value of the page token from the implementation's response as the end of the listing results.
- `on` string, required
- `when_matched_update_all` boolean
- `when_matched_update_all_filt` string
- `when_not_matched_insert_all` boolean
- `when_not_matched_by_source_delete` boolean
- `when_not_matched_by_source_delete_filt` string

## Response `200`

Result of merge insert operation

- MergeInsertIntoTableResponse — 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

- **2025-07-22** `ac7519693c52` — 1 breaking, 9 info
  - removed the media type `application/x-arrow-ipc` from the request body
  - added the new optional `query` request parameter `delimiter` to all path's operations
  - added the new optional `query` request parameter `when_matched_update_all_filt` to all path's operations
  - added the new optional `query` request parameter `when_not_matched_by_source_delete` to all path's operations
  - …6 more
- **2025-07-21** `db7569410aa4` — 2 info
  - api operation id `MergeInsertTable` removed and replaced with `MergeInsertIntoTable`
  - api tag `Data` added
- **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/8769f8e36bc4/schema)