---
title: "What a schema change would break"
description: "Given fields or tables you propose to remove, lists the permission rules, saved views, pages and other fields that read them, the same list `fields.delete` and `tables.delete` are refused with until you send acknowledge=true."
canonical: "https://gtable.app/docs/builder-api/schema/impact"
updated: "2026-10-05"
---

# What a schema change would break

`POST https://studio.gtable.app/v1/apps/{appId}/schema/impact`

Given fields or tables you propose to remove, lists the permission rules, saved views, pages and other fields that read them, the same list `fields.delete` and `tables.delete` are refused with until you send acknowledge=true.

Pages are matched by what their code named when it was last built. References are by id, so a rename breaks nothing and is answered with nothing. Advisory: nothing is changed.

Requires the `schema:read` scope. Operation `schema.impact`. MCP tool `schema_impact`. CLI, once published: `gtable schema impact`.

## Path parameters

| Name    | Type   | Required | Description |
| ------- | ------ | -------- | ----------- |
| `appId` | string | yes      |             |

## Headers

| Name              | Type   | Required | Description                                                                                                                                                                                                                                                        |
| ----------------- | ------ | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `Idempotency-Key` | string | no       | Any unique string. Sending the same key with the same request again returns the first response (marked `Idempotency-Replayed: true`) instead of running it twice. Reusing it for a different request is refused with 409. Kept for 24 hours. Up to 255 characters. |

## Request body

| Field     | Type      | Required | Description   |
| --------- | --------- | -------- | ------------- |
| `drops`   | object\[] | no       | Default `[]`. |
| `renames` | object\[] | no       | Default `[]`. |