# Fit columns to a layout

Shape / columns

fit columns to a target layout

Page: <https://meridian.online/operations/fit-columns-to-a-layout>

## Status

Runs as a SQL step.

arcform carries it as a `sql:` step today.

## The DuckDB step

fit columns to a target layout from a mapping

It reads the `orders` table the proofs share. Create it first:

```sql
CREATE TABLE orders AS SELECT * FROM (VALUES
  (1,  'Alice Ng',      'north', DATE '2026-01-03', 120.00, 'widget', 'a|b',   '{"channel":"web","items":[1,2]}'),
  (2,  'alice ng',      'north', DATE '2026-01-05',  80.50, 'gadget', 'b',     '{"channel":"shop","items":[3]}'),
  (3,  'Bob  Okafor',   'south', DATE '2026-01-05', 300.00, 'widget', 'a|c',   '{"channel":"web","items":[4,5,6]}'),
  (4,  'Carla Díaz',    'east',  DATE '2026-01-09',  NULL,  'gizmo',  NULL,    '{"channel":"web","items":[]}'),
  (5,  'Bob Okafor',    'south', DATE '2026-01-12',  45.25, 'gadget', 'c',     '{"channel":"phone","items":[7]}'),
  (6,  'Dev Patel',     'west',  DATE '2026-01-12', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (7,  'Carla Diaz',    'east',  DATE '2026-01-20',  99.99, 'gizmo',  'b|c',   '{"channel":"shop","items":[10]}'),
  (8,  'Dev Patel',     'west',  DATE '2026-02-02', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (9,  'Eve Larsen',    NULL,    DATE '2026-02-03',  15.00, 'gadget', NULL,    '{"channel":"web","items":[11]}'),
  (10, 'Alice Ng',      'north', DATE '2026-02-10', 220.00, 'gizmo',  'a|b|c', '{"channel":"phone","items":[12,13]}')
) t(order_id, customer, region, order_date, amount, product, tags, meta);
```

Then run the statement:

```sql
CREATE TABLE target_layout (customer_name VARCHAR, order_total DOUBLE, placed DATE);
INSERT INTO target_layout BY NAME SELECT order_date AS placed, amount AS order_total, customer AS customer_name FROM orders;
CREATE TEMP TABLE result AS
SELECT count(*) AS n, count(order_total) AS totals, min(placed) AS first_placed, max(customer_name) FILTER (WHERE order_total = 220) AS who FROM target_layout;
SELECT * FROM result;
SELECT CASE WHEN ((SELECT n = 10 AND totals = 9 AND first_placed = DATE '2026-01-03' AND who = 'Alice Ng' FROM result)) THEN 'as expected' ELSE error('the columns did not land in the target by name') END AS verdict;
```

It needs nothing installed beyond DuckDB itself.

## What other tools call it

Meridian's classification; an independent blind rating agreed on 86.2% of 312 rows (exact class, version 2).

- Alteryx Designer: [`Schema Fit`](https://help.alteryx.com/current/en/designer/tools/ai-tools/schema-fit-tool.html) (read 2026-09-27)
- Apache NiFi: [`ConvertRecord`](https://nifi.apache.org/components/org.apache.nifi.processors.standard.ConvertRecord/) (read 2026-09-27)
- OpenRefine: [`Edit Wikidata schema`](https://openrefine.org/docs/manual/wikibase/overview#wikidata-schema) (read 2026-09-27)
- RapidMiner Studio: [`Superset`](https://docs.rapidminer.com/latest/studio/operators/blending/table/joins/superset.html) (read 2026-09-27)