# Keep rows by their positions

Shape / rows

A variant of [Take the first or last rows](https://meridian.online/operations/take-the-first-or-last-rows).

Keep rows at listed line numbers or in several separate ranges of positions.

Page: <https://meridian.online/operations/take-the-first-or-last-rows/keep-rows-by-their-positions>

## Status

Runs as a SQL step.

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

## The DuckDB step

keep rows at listed positions and in separate ranges of positions

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 numbered AS
SELECT row_number() OVER (ORDER BY order_id) AS pos, order_id, customer FROM orders;
-- listed positions
CREATE TEMP TABLE listed AS SELECT pos, order_id FROM numbered WHERE pos IN (2, 5, 9);
-- several separate ranges
CREATE TEMP TABLE ranges AS SELECT pos, order_id FROM numbered WHERE pos BETWEEN 1 AND 2 OR pos BETWEEN 8 AND 10;
-- one range, as a page
CREATE TEMP TABLE page AS SELECT pos, order_id FROM numbered ORDER BY pos LIMIT 3 OFFSET 4;
SELECT * FROM listed ORDER BY pos;
SELECT * FROM ranges ORDER BY pos;
SELECT CASE WHEN ((SELECT list(pos ORDER BY pos) FROM listed) = [2, 5, 9] AND (SELECT list(pos ORDER BY pos) FROM ranges) = [1, 2, 8, 9, 10] AND (SELECT list(pos ORDER BY pos) FROM page) = [5, 6, 7]) THEN 'as expected' ELSE error('the listed positions, the two ranges or the page were not the expected rows') 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).

- Alteryx Designer: [`Select Records`](https://help.alteryx.com/current/en/designer/tools/preparation/select-records-tool.html) (read 2026-09-27)
- Apache Hop: [`Sample Rows`](https://hop.apache.org/manual/latest/pipeline/transforms/samplerows.html) (read 2026-09-27)
- Pentaho Data Integration: [`Sample rows`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)
- Polars: [`DataFrame.gather`](https://docs.pola.rs/api/python/stable/reference/dataframe/modify_select.html) (read 2026-09-27)
- Talend: [`tSampleRow`](https://help.qlik.com/talend/en-US/components/8.0/processing/processing-component) (read 2026-09-27)