docs/api/sql/Geometry-Editors/ST_RemoveRepeatedPoints.md

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# ST_RemoveRepeatedPoints

Introduction: This function eliminates consecutive duplicate points within a geometry, preserving endpoints of LineStrings. It operates on (Multi)LineStrings, (Multi)Polygons, and MultiPoints, processing GeometryCollection elements individually. When an optional 'tolerance' value is provided, vertices within that distance are also considered duplicates.

![ST_RemoveRepeatedPoints](../../../image/ST_RemoveRepeatedPoints/ST_RemoveRepeatedPoints.svg "ST_RemoveRepeatedPoints")

Format:

`ST_RemoveRepeatedPoints(geom: Geometry, tolerance: Double)`

`ST_RemoveRepeatedPoints(geom: Geometry)`

Return type: `Geometry`

Since: `v1.7.0`

SQL Example:

```sql
SELECT ST_RemoveRepeatedPoints(
        ST_GeomFromWKT('MULTIPOINT ((20 20), (10 10), (30 30), (40 40), (20 20), (30 30), (40 40))')
       )
```

Output:

```
MULTIPOINT ((20 20), (10 10), (30 30), (40 40))
```

SQL Example:

```sql
SELECT ST_RemoveRepeatedPoints(
        ST_GeomFromWKT('LINESTRING (20 20, 10 10, 30 30, 40 40, 20 20, 30 30, 40 40)')
       )
```

Output:

```
LINESTRING (20 20, 10 10, 30 30, 40 40, 20 20, 30 30, 40 40)
```

SQL Example: Each geometry within a collection is processed independently.

```sql
ST_RemoveRepeatedPoints(
        ST_GeomFromWKT('GEOMETRYCOLLECTION (POINT (10 10), POINT(10 10), LINESTRING (20 20, 20 20, 30 30, 30 30), MULTIPOINT ((80 80), (90 90), (90 90), (100 100)))')
    )
```

Output:

```
GEOMETRYCOLLECTION (POINT (10 10), POINT (10 10), LINESTRING (20 20, 30 30), MULTIPOINT ((80 80), (90 90), (100 100)))
```

SQL Example: Elimination of repeated points within a specified distance tolerance.

```sql
SELECT ST_RemoveRepeatedPoints(
        ST_GeomFromWKT('LINESTRING (20 20, 10 10, 30 30, 40 40, 20 20, 30 30, 40 40)'),
        20
       )
```

Output:

```
LINESTRING (20 20, 40 40, 20 20, 40 40)
```