---
title: "POST /api/transform/extract-columns"
method: POST
path: "/api/transform/extract-columns"
tags: ["/api/transform"]
---

# POST /api/transform/extract-columns

`POST /api/transform/extract-columns`

Extract column names suitable for incremental transform checkpoint filtering.

  This endpoint is specifically for populating the checkpoint column dropdown in
  incremental transforms. It only returns columns with types supported for checkpoint
  filtering: temporal (timestamp/tz) and numeric (int/float) types.

  Text, boolean, and other unsupported column types are filtered out.

  The query is compiled to native SQL using [[qp.compile/compile-with-inline-parameters]],
  which handles parameterized queries with template tags. Then extracts column names
  and types using PreparedStatement metadata.

  Returns a map with a :columns key containing a vector of column names (strings).
  If extraction fails, returns nil for :columns.

## Request body

- object
  - `query` MetabaseQueryProcessorSchemaAnyQuery, required — Schema for a map that is in the general shape of either a legacy MBQL or MBQL 5 query. Query may not be normalized yet! This schema is not very strict because we need to handle different types of queries (legacy MBQL, pMBQL, super-legacy MBQL, internal audit app queries, etc.) and it might not be normalized yet.
    - `database` union
      - integer — Valid Database ID
      - unknown

## Response `2XX`

Successful response

- object
  - `columns` string[], nullable, required

## Other responses

- `4XX` — Client error response
- `5XX` — Server error response

## Changes

- **2026-03-09** `78297d193ca4` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/metabase/apis/metabase-api/changes/api/transform/extract-columns/post.md)

---

[API](https://skmtc.dev/metabase/apis/metabase-api.md) · [All operations](https://skmtc.dev/metabase/apis/metabase-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/metabase/metabase-api/revisions/78297d193ca4/schema)