# Split columns into two tables

Shape / columns

A variant of [Choose and rename columns](https://meridian.online/operations/choose-and-rename-columns).

Send the chosen columns to one output table and the remaining columns to a second.

Page: <https://meridian.online/operations/choose-and-rename-columns/split-columns-into-two-tables>

## Status

Runs as a SQL step.

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

## The DuckDB step

send the chosen columns to one table and the rest to another, keeping order\_id in both as the rejoin key

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 TEMP TABLE chosen AS SELECT order_id, customer, amount FROM orders;
CREATE TEMP TABLE remainder AS SELECT * EXCLUDE (customer, amount) FROM orders;
SELECT * FROM chosen LIMIT 3;
SELECT * FROM remainder LIMIT 3;
SELECT CASE WHEN ((SELECT list(column_name) FROM (DESCRIBE chosen)) = ['order_id', 'customer', 'amount'] AND (SELECT list(column_name) FROM (DESCRIBE remainder)) = ['order_id', 'region', 'order_date', 'product', 'tags', 'meta'] AND (SELECT count(*) FROM chosen c JOIN remainder r USING (order_id)) = 10) THEN 'as expected' ELSE error('the two tables were not the chosen three columns and the six that remain, joined by order_id') END AS verdict;
```

It needs nothing installed beyond DuckDB itself.

## What other tools call it

Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3).

- AWS Glue: [`SplitFields`](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-pyspark-transforms-SplitFields.html) (read 2026-09-27)
- AWS Glue: [`SplitFields`](https://docs.aws.amazon.com/glue/latest/dg/transforms-configure-split-fields.html) (read 2026-09-27)
- KNIME Analytics Platform: [`Column Splitter`](https://api.hub.knime.com/nodes/*vaFt1v7ILO7_NMkm?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Reference Column Splitter`](https://api.hub.knime.com/nodes/*jBqr78UOHDsE2AoZ?details=full) (read 2026-09-27)