# Keep groups after aggregating

Shape / rows

A variant of [Filter rows](https://meridian.online/operations/filter-rows).

Keep the groups whose aggregate values meet a condition.

Page: <https://meridian.online/operations/filter-rows/keep-groups-after-aggregating>

## Status

Runs as a SQL step.

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

## The DuckDB step

keep the groups whose total meets a condition, after grouping

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 product, count(*) AS orders, sum(amount) AS total
FROM orders
GROUP BY product
HAVING sum(amount) >= 319.99;
SELECT * FROM result ORDER BY product;
SELECT CASE WHEN ((SELECT list((product, orders, total) ORDER BY product) FROM result) = [('gizmo', 3, 319.99), ('widget', 4, 1440.00)]) THEN 'as expected' ELSE error('HAVING did not keep exactly gizmo (319.99, on the boundary) and widget (1440.00) and drop gadget (140.75)') 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).

- Apache DataFusion: [`Filter post-aggregate (HAVING)`](https://datafusion.apache.org/user-guide/features.html) (read 2026-09-27)
- DuckDB: [`HAVING (clause)`](https://duckdb.org/docs/current/sql/query_syntax/having) (read 2026-09-27)
- Polars: [`GroupBy.having`](https://docs.pola.rs/api/python/stable/reference/dataframe/group_by.html) (read 2026-09-27)
- SQLMesh: [`@HAVING`](https://github.com/SQLMesh/sqlmesh/blob/23b237cea7218cc8f338b89c14f0957394a0003b/docs/concepts/macros/sqlmesh_macros.md) (read 2026-09-27)