---
title: Histogram
description: Count the number of occurrences over some interval
canonical: https://docs.paradedb.com/documentation/aggregates/bucket/histogram
---

The histogram aggregation dynamically creates buckets for a given `interval` and counts the number of occurrences
in each bucket.

Each value is rounded down to its bucket. For instance, a rating of `18` with an interval of `5` rounds down to a bucket
with key `15`.

<CodeGroup>
```sql SQL
SELECT pdb.agg('{"histogram": {"field": "rating", "interval": "1"}}')
FROM mock_items
WHERE id @@@ pdb.all();
```

```python Django
from paradedb import Agg, All, ParadeDB

MockItem.objects.filter(
    id=ParadeDB(All())
).aggregate(agg=Agg('{"histogram": {"field": "rating", "interval": "1"}}'))
```

```python SQLAlchemy
from sqlalchemy import select
from sqlalchemy.orm import Session
from paradedb.sqlalchemy import facets, pdb, search

stmt = (
    select(pdb.agg(facets.histogram(field="rating", interval=1)))
    .select_from(MockItem)
    .where(search.all(MockItem.id))
)

with Session(engine) as session:
    session.execute(stmt).all()
```

```ruby Rails
MockItem.search(:id)
        .match_all
        .facets_agg(agg: ParadeDB::Aggregations.histogram(:rating, interval: 1))
```

</CodeGroup>

```ini Expected Response
                                                                                  agg
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 {"buckets": [{"key": 1.0, "doc_count": 1}, {"key": 2.0, "doc_count": 3}, {"key": 3.0, "doc_count": 9}, {"key": 4.0, "doc_count": 16}, {"key": 5.0, "doc_count": 12}]}
(1 row)
```

See the [Tantivy documentation](https://docs.rs/tantivy/latest/tantivy/aggregation/bucket/struct.HistogramAggregation.html)
for all available options.
