> ## Documentation Index
> Fetch the complete documentation index at: https://cockroachlabs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# SRID 4326 - longitude and latitude

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Every geometric shape has a spatial reference system associated with it, and each such reference system has a Spatial Reference System ID (<InternalLink path="architecture/glossary#srid">SRID</InternalLink>).  The SRID is used to tell which spatial reference system will be used to interpret each spatial object.

A common SRID in use is 4326, which represents spatial data using longitude and latitude coordinates on the Earth's surface as defined in the <InternalLink path="architecture/glossary#wgs84">WGS84</InternalLink> standard, which is also used for the [Global Positioning System (GPS)](https://wikipedia.org/wiki/Global_Positioning_System).

Here is an example shape that uses SRID 4326, a line stretching from Milwaukee, WI to Tulsa, OK:

```
SRID=4326;LINESTRING( -87.906471 43.038902, -95.992775 36.153980)
```

Most users should only have to care about SRIDs in the following situations:

* When creating shapes.  By default, shapes which do not have an SRID associated with them will use an SRID of 0, which means "this shape has no SRID".
* When comparing shapes. If you try to compare two shapes with different SRIDs using a spatial predicate, CockroachDB will signal an error.

## Adding SRIDs to shapes

### Add an SRID with WKT

To add an SRID to a shape you are defining with <InternalLink path="well-known-text">Well Known Text</InternalLink>, prepend the text with `SRID=N;` as shown below:

```
SRID=4326;POLYGON((-79.976111 40.374444, -74.621157 40.323294, -76.609383 39.299236, -79.976111 40.374444))
```

### Add an SRID with SQL

To add an SRID to a shape in SQL, use the `ST_SetSRID` <InternalLink path="functions-and-operators">function</InternalLink>:

```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
select ST_SetSRID(ST_MakePoint(1,2), 4326);
```

```
                      st_setsrid
------------------------------------------------------
  0101000020E6100000000000000000F03F0000000000000040
(1 row)
```

### Change a shape's SRID

To convert a shape to use a different SRID while maintaining the same reference location, use the `ST_Transform` function.  In the example below, we transform the reference system for a line from Albany, NY to Saranac Lake, NY from 4326 to use the [StatePlane New York East reference (SRID 3101)](https://epsg.io/102715).  This can be useful (or at least interesting) in some situations, since the StatePlane systems give distances in feet.

```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
select ST_Transform(ST_GeomFromText('SRID=4326;LINESTRING(-73.756233 42.652580, -74.130833 44.326111)'),3101);
```

```
                                         st_transform
----------------------------------------------------------------------------------------------
  01020000201D0C000002000000487C82CDD54D4D41EC8A5DA9AD726B4181403E98D7B34C417A15F9897C116B41
(1 row)
```

<Danger>
  When setting a shape's SRID, you can only use SRIDs that are defined in the <InternalLink path="architecture/glossary#spatial_ref_sys">`spatial_ref_sys`</InternalLink> table.  For more information, see [Getting SRID information](#getting-srid-information).
</Danger>

## Getting SRID information

You can get more detailed information about the SRIDs supported in CockroachDB from the <InternalLink path="cockroach-sql">SQL client</InternalLink> by querying the <InternalLink path="architecture/glossary#spatial_ref_sys">`spatial_ref_sys`</InternalLink> table.

To see how many SRIDs are supported, run the following query:

```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT count(*) FROM spatial_ref_sys;
```

```
  count
---------
   6139
(1 row)
```

To get more information about a specific SRID (in this case 4326), run the following query:

```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
SELECT * FROM spatial_ref_sys WHERE srid = 4326;
```

```
  srid | auth_name | auth_srid |                                                                                                                              srtext                                                                                                                              |              proj4text
-------+-----------+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------
  4326 | EPSG      |      4326 | GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]] | +proj=longlat +datum=WGS84 +no_defs
(1 row)
```

## Comparing shapes with different SRIDs

If you try to compare two shapes with different SRIDs using a spatial predicate, CockroachDB will signal an error:

```sql theme={"theme":{"light":"catppuccin-mocha","dark":"catppuccin-mocha"}}
select ST_Contains(ST_MakePoint(1,2), ST_SetSRID(ST_MakePoint(1,2), 4326));
```

```
ERROR: st_contains(): operation on mixed SRIDs forbidden: (Point, 0) != (Point, 4326)
```

## Known limitations

Defining a custom SRID by inserting rows into <InternalLink path="architecture/glossary#spatial_ref_sys">`spatial_ref_sys`</InternalLink> is not currently supported.

## See also

* <InternalLink path="spatial-data-overview">Spatial Data Overview</InternalLink>
* <InternalLink path="spatial-tutorial">Spatial tutorial</InternalLink>
* <InternalLink path="spatial-indexes">Spatial indexes</InternalLink>
* <InternalLink path="architecture/glossary">Spatial and GIS Glossary of Terms</InternalLink>
* <InternalLink path="well-known-text">Well known text</InternalLink>
* <InternalLink path="well-known-binary">Well known binary</InternalLink>
* <InternalLink path="geojson">GeoJSON</InternalLink>
* [Introducing Distributed Spatial Data in CockroachDB](https://www.cockroachlabs.com/blog/spatial-data/) (blog post)
* <InternalLink path="geoserver">Using GeoServer with CockroachDB</InternalLink>