# Extract with a regular expression

Shape / columns

A variant of [Match with a regular expression](https://meridian.online/operations/match-with-a-regular-expression).

Copy the parts of a value that match a pattern, or its capture groups, into new columns or an array.

Page: <https://meridian.online/operations/match-with-a-regular-expression/extract-with-a-regular-expression>

## Status

Runs as a SQL step.

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

## The DuckDB step

copy a capture group, and every match, out of a value

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 result AS
SELECT order_id, regexp_extract(meta, '"channel":"(\w+)"', 1) AS channel, regexp_extract_all(meta, '\d+') AS item_ids FROM orders;
SELECT * FROM result;
SELECT CASE WHEN ((SELECT count(*) FILTER (WHERE channel = 'web') FROM result) = 6 AND (SELECT count(*) FILTER (WHERE channel = 'phone') FROM result) = 2 AND (SELECT item_ids FROM result WHERE order_id = 3) = ['4', '5', '6'] AND (SELECT sum(len(item_ids)) FROM result) = 15) THEN 'as expected' ELSE error('the channel group and the item numbers were not pulled out of the JSON text') 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).

- Duckle: [`Regex Extract`](https://github.com/slothflowlabs/duckle/blob/f85f8960edfb6efbf4cb89d58a7b32e16df0e867/website/docs/components.html) (read 2026-09-25)
- EasyMorph: [`Regular expression`](https://help.easymorph.com/doku.php?id=transformations:regexp) (read 2026-09-27)
- AWS Glue: [`Extract string fragments from a regular expression`](https://docs.aws.amazon.com/glue/latest/dg/transforms-regex-extractor.html) (read 2026-09-27)
- Apache Hop: [`Regex Evaluation`](https://hop.apache.org/manual/latest/pipeline/transforms/regexeval.html) (read 2026-09-27)
- Ibis: [`RegexExtract`](https://github.com/ibis-project/ibis/blob/05d2b293344e86cb41c1a426071734f7e270335a/ibis/expr/operations/strings.py) (read 2026-09-27)
- Ibis: [`RegexSplit`](https://github.com/ibis-project/ibis/blob/05d2b293344e86cb41c1a426071734f7e270335a/ibis/expr/operations/strings.py) (read 2026-09-27)
- KNIME Analytics Platform: [`String Splitter (Regex)`](https://api.hub.knime.com/nodes/*KUuLa8QggcD_9C01?details=full) (read 2026-09-27)
- Apache NiFi: [`ExtractGrok`](https://nifi.apache.org/components/org.apache.nifi.processors.standard.ExtractGrok/) (read 2026-09-27)
- Apache NiFi: [`ExtractText`](https://nifi.apache.org/components/org.apache.nifi.processors.standard.ExtractText/) (read 2026-09-27)
- Pentaho Data Integration: [`Regex Evaluation`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)
- RapidMiner Studio: [`Keep Document Parts`](https://docs.rapidminer.com/latest/studio/operators/extensions/Text%20Processing/transformation/keep_document_parts.html) (read 2026-09-27)
- Apache SeaTunnel: [`RegexExtract`](https://seatunnel.apache.org/docs/2.3.13/transforms/regexextract) (read 2026-09-27)
- Talend: [`tExtractRegexFields`](https://help.qlik.com/talend/en-US/components/8.0/data-extraction/data-extraction-component) (read 2026-09-27)
- Talend: [`tPatternExtract`](https://help.qlik.com/talend/en-US/components/8.0/data-extraction/data-extraction-component) (read 2026-09-27)
- Talend: [`tStandardizeRow`](https://help.qlik.com/talend/en-US/components/8.0/standardization/standardization-component) (read 2026-09-27)
- Trifacta: [`Extract Transform`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/language-appendices/transforms.html) (read 2026-09-27)
- Trifacta: [`Extract between delimiters`](https://help.alteryx.com/aac/en/trifacta-classic/reference/transformation-reference.html) (read 2026-09-27)
- Trifacta: [`Extract matches to Array`](https://help.alteryx.com/aac/en/trifacta-classic/reference/transformation-reference.html) (read 2026-09-27)
- Trifacta: [`Extract numbers`](https://help.alteryx.com/aac/en/trifacta-classic/reference/transformation-reference.html) (read 2026-09-27)
- Trifacta: [`Extract text or pattern`](https://help.alteryx.com/aac/en/trifacta-classic/reference/transformation-reference.html) (read 2026-09-27)
- Trifacta: [`Extractlist Transform`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/language-appendices/transforms.html) (read 2026-09-27)
- VisiData: [`addcol-capture`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/features/regex.py#L139) (read 2026-09-23)
- VisiData: [`capture-col`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/deprecated.py#L237) (read 2026-09-23)
