---
title: "DEDUPE"
sidebarTitle: "DEDUPE"
description: "The dedupe() table function: one representative row per near-duplicate group, scanned over the index."
icon: layer-group
keywords: ["dedupe", "vector_dedup", "sql", "deduplication", "near-duplicate", "table function"]
availability:
  embedded: unavailable
  enterprise: available
---

`dedupe` scans a vector column's [index](/indexing/vector-index) partitions
for rows closer than a distance threshold, resolves the overlapping pairs it
finds into duplicate groups, and returns one representative row per group --
without a full pairwise scan or a shuffle. See
[`duplicate_pairs`](/sql/dql/duplicate-pairs) to inspect the pairs themselves
before committing to this resolution.

<CodeGroup>
```sql SQL icon="database"
SELECT * FROM dedupe(
    <table>,
    <vector_column>,
    distance_threshold => <float>
    [, resolution => 'connected_components' | 'direct_representative']
)
```
</CodeGroup>

<CodeGroup>
```sql SQL icon="database"
SELECT * FROM dedupe(
    'frames',
    'vec',
    distance_threshold => 0.02
)
```
</CodeGroup>

<Note>
Earlier releases spelled this `vector_dedup`; that name is rejected on
current deployments.
</Note>

## Input {#input}

| Argument | Type | Required | Meaning |
| --- | --- | --- | --- |
| table name | string literal | yes | the table to scan |
| vector column | string literal | yes | the indexed vector column to compare |
| `distance_threshold` | float | yes | maximum distance for a pair to count as close |
| `resolution` | `'connected_components'` (default) \| `'direct_representative'` | no | how overlapping pairs group together -- see [Resolution](#resolution) |

`dedupe` always scans every partition and returns original rows -- sampling
a subset of partitions and `id_column` are pair-query-only options, accepted
by [`duplicate_pairs`](/sql/dql/duplicate-pairs#input) but refused here.

## Output {#output}

One row per duplicate group, **in the table's own schema** -- every column of
`<table>`, including a BlobV2 column, comes through unchanged on the
representative row Lance selected for that group. Unlike
[`duplicate_pairs`](/sql/dql/duplicate-pairs#output), there is no fixed
`dedupe`-specific schema to document: the output schema is the source
table's schema.

Because the result is already shaped like the table, it composes directly
into a new table or a materialized view:

<CodeGroup>
```sql SQL icon="database"
CREATE MATERIALIZED VIEW frames_deduped AS
SELECT * FROM dedupe(
    'frames',
    'vec',
    distance_threshold => 0.02
)
```
</CodeGroup>

## Resolution {#resolution}

`resolution` chooses how overlapping pairs group together:

| `resolution` value | How pairs group |
| --- | --- |
| `connected_components` (default) | groups transitively: if a~b and b~c are both close, all three resolve together |
| `direct_representative` | only pairs within the threshold of each other resolve together |

## Estimating on a sample first {#sampling}

`dedupe` itself always scans every partition. To estimate a duplicate rate
on a large table before committing to a full scan, sample partitions with
[`duplicate_pairs`](/sql/dql/duplicate-pairs#sampling) instead, which
accepts `selection`, `count` and `seed` for exactly this.

## What to read next {#next}

<CardGroup cols={2}>
  <Card title="DUPLICATE_PAIRS" icon="clone" href="/sql/dql/duplicate-pairs">
    Inspect the close pairs themselves instead of the resolved groups.
  </Card>
  <Card title="Deduplicate near-duplicates" icon="copy" href="/curation/dedupe">
    When to reach for this instead of exact-key deduplication.
  </Card>
</CardGroup>