---
title: Relevance Tuning
description: Tune the BM25 score by adjusting the weights of individual queries
canonical: https://docs.paradedb.com/documentation/sorting/boost
---

## Boosting

ParadeDB offers several ways to tune a document's [BM25 score](/documentation/sorting/score).
The first is boosting, which increases or decreases the impact of a specific query by multiplying its contribution to the overall BM25 score.

To boost a query, cast the query to the `boost` type. In this example, the `shoes` query is weighted twice as heavily as the `footwear` query.

```sql
SELECT id, pdb.score(id), description, category
FROM mock_items
WHERE description ||| 'shoes'::pdb.boost(2) OR category ||| 'footwear'
ORDER BY score DESC
LIMIT 5;
```

`boost` takes a numeric value, which is the multiplicative boost factor. It can be any floating point number between `-2048` and `2048`.

[Query builder functions](/documentation/query-builder/overview) can also be boosted:

```sql
SELECT id, description, category, pdb.score(id)
FROM mock_items
WHERE description @@@ pdb.regex('key.*')::pdb.boost(2)
ORDER BY score DESC
LIMIT 5;
```

Boost can be used in conjunction with other type casts, like [fuzzy](/documentation/full-text/fuzzy):

```sql
SELECT id, description, category, pdb.score(id)
FROM mock_items
WHERE description ||| 'shose'::pdb.fuzzy(2)::pdb.boost(2)
ORDER BY score DESC
LIMIT 5;
```

## Constant Scoring

Constant scoring assigns the same score to all documents that match a query. To apply a constant score, cast the query to the `const` type with a
numeric value.

For instance, the following query assigns a score of `1` to all documents matching the query `shoes`.

```sql
SELECT id, pdb.score(id), description, category
FROM mock_items
WHERE description ||| 'shoes'::pdb.const(1)
ORDER BY score DESC
LIMIT 5;
```
