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

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

```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.