The geography functions operate on or generate BigQuery
`GEOGRAPHY`

values. The signature of any geography
function starts with `ST_`

. BigQuery supports the following functions
that can be used to analyze geographical data, determine spatial relationships
between geographical features, and construct or manipulate
`GEOGRAPHY`

s.

The geography functions are grouped into the following categories based on their behavior:

**Constructors**: Functions that build new`GEOGRAPHY`

values from coordinates or existing`GEOGRAPHY`

s, such as`ST_GEOGPOINT`

.**Parsers**: Functions that create`GEOGRAPHY`

s from an external format such as WKT and GeoJSON. For example,`ST_GEOGFROMTEXT`

, creates a`GEOGRAPHY`

from WKT.**Formatters**: Functions that export`GEOGRAPHY`

s to an external format such as WKT and GeoJSON. For example,`ST_ASTEXT`

formats a`GEOGRAPHY`

to WKT.**Transformations**: Functions that generate a new`GEOGRAPHY`

from others that adhere to some property. Examples include`ST_INTERSECTION`

and`ST_BOUNDARY`

.**Predicates**: Functions that return`TRUE`

or`FALSE`

for some spatial relationship between two`GEOGRAPHY`

s, or for some property of a geography. These functions are commonly used in filter clauses. For example,`ST_DWITHIN`

is a predicate.**Accessors**: Functions that provide access to properties of a`GEOGRAPHY`

without side-effects, such as`ST_NUMPOINTS`

.**Measures**: Functions that compute measurements of one or more`GEOGRAPHY`

, for example`ST_DISTANCE`

.**Aggregate Functions**: Geography-specific aggregate functions, such as`ST_UNION_AGG`

.

All BigQuery geography functions return `NULL`

if any input argument
is `NULL`

.

### ST_GEOGPOINT

```
ST_GEOGPOINT(longitude, latitude)
```

**Description**

Creates a `GEOGRAPHY`

with a single point.
`ST_GEOGPOINT`

creates a point from the specified
`FLOAT64`

longitude and latitude parameters and
returns that point in a `GEOGRAPHY`

value.

**Constraints**

- Latitudes must be in the range [-90, 90]. Latitudes outside this range will result in an error.
- Longitudes outside the range [-180, 180] are allowed;
`ST_GEOGPOINT`

uses the input longitude modulo 360 to obtain a longitude within [-180, 180].

**Return type**

`GEOGRAPHY`

### ST_MAKELINE

```
ST_MAKELINE(geography_1, geography_2)
```

```
ST_MAKELINE(array_of_geography)
```

**Description**

Creates a `GEOGRAPHY`

with a single linestring by
concatenating the point or line vertices of each of the input
`GEOGRAPHY`

s in the order they are given.

Input can either be two `GEOGRAPHY`

s or an
`ARRAY`

of type
`GEOGRAPHY`

. Each input
`GEOGRAPHY`

must consist of one of the following
values:

- Exactly one point.
- Exactly one linestring.

**Constraints**

Every edge must span strictly less than 180 degrees.

NOTE: BigQuery's snapping process may discard sufficiently short edges
and snap the two endpoints together. For instance, if two input
`GEOGRAPHY`

s each contain a point and the two points
are separated by a distance less than the snap radius, the points will be
snapped together. In such a case the result will be a
`GEOGRAPHY`

with exactly one point.

**Return type**

`GEOGRAPHY`

### ST_MAKEPOLYGON

```
ST_MAKEPOLYGON(geography_expression)
```

```
ST_MAKEPOLYGON(geography_expression, array_of_geography)
```

**Description**

Creates a `GEOGRAPHY`

containing a single polygon
from linestring inputs, where each input linestring is used to construct a
polygon ring.

The linestring input is either provided by a single
`GEOGRAPHY`

containing exactly one linestring, or by
a single `GEOGRAPHY`

and an array of
`GEOGRAPHY`

s, each containing exactly one linestring.
The first `GEOGRAPHY`

will always be used to
construct the polygon shell. Any additional
`GEOGRAPHY`

s beyond the first in the array specify a
polygon hole. For every input `GEOGRAPHY`

containing
exactly one linestring, the following must be true:

- The linestring must consist of at least three distinct vertices.
- The linestring must be closed: that is, the first and last vertex have to be the same. If the first and last vertex differ, the function constructs a final edge from the first vertex to the last.

NOTE: `ST_MAKEPOLYGON`

accepts an empty `GEOGRAPHY`

as input. `ST_MAKEPOLYGON`

interprets an empty
`GEOGRAPHY`

as having an empty linestring, which will
create a full loop: that is, a polygon that covers the entire Earth.

**Constraints**

Together, the input rings must form a valid polygon:

- The polygon shell must cover each of the polygon holes.
- There can be only one polygon shell (which has to be the first input ring). This implies that polygon holes cannot be nested.
- Polygon rings may only intersect in a vertex on the boundary of both rings.

Every edge must span strictly less than 180 degrees.

Each polygon ring divides the sphere into two regions. The first input linesting
to `ST_MAKEPOLYGON`

forms the polygon shell, and the interior is chosen to be
the smaller of the two regions. Each subsequent input linestring specifies a
polygon hole, so the interior of the polygon is already well-defined. In order
to define a polygon shell such that the interior of the polygon is the larger of
the two regions, see `ST_MAKEPOLYGONORIENTED`

.

NOTE: BigQuery's snapping process may discard sufficiently short edges
and snap the two endpoints together. Hence, when vertices are snapped together,
it is possible that a polygon hole that is sufficiently small may disappear, or
the output `GEOGRAPHY`

may contain only a line or a
point.

**Return type**

`GEOGRAPHY`

### ST_MAKEPOLYGONORIENTED

```
ST_MAKEPOLYGONORIENTED(array_of_geography)
```

**Description**

Like `ST_MAKEPOLYGON`

, but the vertex ordering of each input linestring
determines the orientation of each polygon ring. The orientation of a polygon
ring defines the interior of the polygon as follows: if someone walks along the
boundary of the polygon in the order of the input vertices, the interior of the
polygon is on the left. This applies for each polygon ring provided.

This variant of the polygon constructor is more flexible since
`ST_MAKEPOLYGONORIENTED`

can construct a polygon such that the interior is on
either side of the polygon ring. However, proper orientation of polygon rings is
critical in order to construct the desired polygon.

NOTE: The input argument for `ST_MAKEPOLYGONORIENTED`

may contain an empty
`GEOGRAPHY`

. `ST_MAKEPOLYGONORIENTED`

interprets an empty `GEOGRAPHY`

as having an empty
linestring, which will create a full loop: that is, a polygon that covers the
entire Earth.

**Constraints**

Together, the input rings must form a valid polygon:

- The polygon shell must cover each of the polygon holes.
- There must be only one polygon shell, which must to be the first input ring. This implies that polygon holes cannot be nested.
- Polygon rings may only intersect in a vertex on the boundary of both rings.

Every edge must span strictly less than 180 degrees.

`ST_MAKEPOLYGONORIENTED`

relies on the ordering of the input vertices of each
linestring to determine the orientation of the polygon. This applies to the
polygon shell and any polygon holes. `ST_MAKEPOLYGONORIENTED`

expects all
polygon holes to have the opposite orientation of the shell. See
`ST_MAKEPOLYGON`

for an alternate polygon constructor, and
other constraints on building a valid polygon.

NOTE: Due to BigQuery's snapping process, edges with a sufficiently
short length will be discarded and the two endpoints will be snapped to a single
point. Therefore, it is possible that vertices in a linestring may be snapped
together such that one or more edge disappears. Hence, it is possible that a
polygon hole that is sufficiently small may disappear, or the resulting
`GEOGRAPHY`

may contain only a line or a point.

**Return type**

`GEOGRAPHY`

### ST_GEOGFROMGEOJSON

```
ST_GEOGFROMGEOJSON(geojson_string)
```

**Description**

Returns a `GEOGRAPHY`

value that corresponds to the
input GeoJSON representation.

`ST_GEOGFROMGEOJSON`

accepts input that is RFC 7946
compliant.

A BigQuery `GEOGRAPHY`

has spherical
geodesic edges, whereas a GeoJSON `Geometry`

object explicitly has planar edges.
To convert between these two types of edges, BigQuery adds additional
points to the line where necessary so that the resulting sequence of edges
remains within 10 meters of the original edge.

See `ST_ASGEOJSON`

to format a
`GEOGRAPHY`

as GeoJSON.

**Constraints**

The input is subject to the following constraints:

`ST_GEOGFROMGEOJSON`

only accepts JSON geometry fragments and cannot be used to ingest a whole JSON document.- The input JSON fragment must consist of a GeoJSON geometry type, which
includes
`Point`

,`MultiPoint`

,`LineString`

,`MultiLineString`

,`Polygon`

,`MultiPolygon`

, and`GeometryCollection`

. Any other GeoJSON type such as`Feature`

or`FeatureCollection`

will result in an error. - A position in the
`coordinates`

member of a GeoJSON geometry type must consist of exactly two elements. The first is the longitude and the second is the latitude. Therefore,`ST_GEOGFROMGEOJSON`

does not support the optional third element for a position in the`coordinates`

member.

**Return type**

`GEOGRAPHY`

### ST_GEOGFROMTEXT

```
ST_GEOGFROMTEXT(wkt_string)
```

**Description**

Returns a `GEOGRAPHY`

value that corresponds to the
input WKT representation.

To format `GEOGRAPHY`

as WKT, use
`ST_ASTEXT`

.

**Constraints**

All input edges are assumed to be spherical geodesics, and *not* planar straight
lines. For reading data in a planar projection, consider using
`ST_GEOGFROMGEOJSON`

. For
more information on the differences between spherical geodesics and planar
lines, see
Coordinate systems and edges.

**Return type**

`GEOGRAPHY`

### ST_GEOGFROMWKB

```
ST_GEOGFROMWKB(wkb_bytes)
```

**Description**

Returns a `GEOGRAPHY`

value that corresponds to the
input WKB representation.

To format `GEOGRAPHY`

as WKB, use
`ST_ASBINARY`

.

**Constraints**

All input edges are assumed to be spherical geodesics, and *not* planar straight
lines. For reading data in a planar projection, consider using
`ST_GEOGFROMGEOJSON`

.

**Return type**

`GEOGRAPHY`

### ST_ASGEOJSON

```
ST_ASGEOJSON(geography_expression)
```

**Description**

Returns the RFC 7946 compliant GeoJSON
representation of the input `GEOGRAPHY`

.

A BigQuery `GEOGRAPHY`

has spherical
geodesic edges, whereas a GeoJSON `Geometry`

object explicitly has planar edges.
To convert between these two types of edges, BigQuery adds additional
points to the line where necessary so that the resulting sequence of edges
remains within 10 meters of the original edge.

See `ST_GEOGFROMGEOJSON`

to construct a
`GEOGRAPHY`

from GeoJSON.

**Return type**

`STRING`

### ST_ASTEXT

```
ST_ASTEXT(geography_expression)
```

**Description**

Returns the WKT representation of an input
`GEOGRAPHY`

.

See `ST_GEOGFROMTEXT`

to construct a
`GEOGRAPHY`

from WKT.

**Return type**

`STRING`

### ST_ASBINARY

```
ST_ASBINARY(geography_expression)
```

**Description**

Returns the WKB representation of an input
`GEOGRAPHY`

.

See `ST_GEOGFROMWKB`

to construct a
`GEOGRAPHY`

from WKB.

**Return type**

`BYTES`

### ST_BOUNDARY

```
ST_BOUNDARY(geography_expression)
```

**Description**

Returns a single `GEOGRAPHY`

that contains the union
of the boundaries of each component in the given input
`GEOGRAPHY`

.

The boundary of each component of a `GEOGRAPHY`

is
defined as follows:

- The boundary of a point is empty.
- The boundary of a linestring consists of the endpoints of the linestring.
- The boundary of a polygon consists of the linestrings that form the polygon shell and each of the polygon's holes.

**Return type**

`GEOGRAPHY`

### ST_CENTROID

```
ST_CENTROID(geography_expression)
```

**Description**

Returns the *centroid* of the input `GEOGRAPHY`

as a
single point `GEOGRAPHY`

.

The *centroid* of a `GEOGRAPHY`

is the weighted
average of the centroids of the highest-dimensional components in the
`GEOGRAPHY`

. The centroid for components in each
dimension is defined as follows:

- The centroid of points is the arithmetic mean of the input coordinates.
- The centroid of linestrings is the centroid of all the edges weighted by length. The centroid of each edge is the geodesic midpoint of the edge.
- The centroid of a polygon is its center of mass.

If the input `GEOGRAPHY`

is empty, an empty
`GEOGRAPHY`

is returned.

**Constraints**

In the unlikely event that the centroid of a
`GEOGRAPHY`

cannot be defined by a single point on
the surface of the Earth, a deterministic but otherwise arbitrary point is
returned. This can only happen if the centroid is exactly at the center of the
Earth, such as the centroid for a pair of antipodal points, and the likelihood
of this happening is vanishingly small.

**Return type**

`GEOGRAPHY`

### ST_CLOSESTPOINT

```
ST_CLOSESTPOINT(geography_1, geography_2[, spheroid=FALSE])
```

**Description**

Returns a `GEOGRAPHY`

containing a point on
`geography_1`

with the smallest possible distance to `geography_2`

. This implies
that the distance between the point returned by `ST_CLOSESTPOINT`

and
`geography_2`

is less than or equal to the distance between any other point on
`geography_1`

and `geography_2`

.

If either of the input `GEOGRAPHY`

s is empty,
`ST_CLOSESTPOINT`

returns `NULL`

.

The `spheroid`

parameter determines how distance is measured for this function.
If `spheroid`

is set to `FALSE`

, then distance is measured on the surface of a
perfect sphere. If `spheroid`

is set to `TRUE`

, distance is measured on the
surface of the WGS84 spheroid. The default for the `spheroid`

parameter is `FALSE`

.

**Return type**

`GEOGRAPHY`

### ST_DIFFERENCE

```
ST_DIFFERENCE(geography_1, geography_2)
```

**Description**

Returns a `GEOGRAPHY`

that represents the point set
difference of `geography_1`

and `geography_2`

.

If `geometry_1`

is completely contained in `geometry_2`

, then `ST_DIFFERENCE`

returns an empty `GEOGRAPHY`

.

**Constraints**

The underlying geometric objects that a BigQuery
`GEOGRAPHY`

represents correspond to a *closed* point
set. Therefore, `ST_DIFFERENCE`

is the closure of the point set difference of
`geography_1`

and `geography_2`

. This implies that if `geography_1`

and
`geography_2`

intersect, then a portion of the boundary of `geography_2`

could
be in the difference.

**Return type**

`GEOGRAPHY`

### ST_INTERSECTION

```
ST_INTERSECTION(geography_1, geography_2)
```

**Description**

Returns a `GEOGRAPHY`

that represents the point set
intersection of the two input `GEOGRAPHY`

s. Thus,
every point in the intersection appears in both `geography_1`

and `geography_2`

.

If the two input `GEOGRAPHY`

s are disjoint, that is,
there are no points that appear in both input `geometry_1`

and `geometry_2`

,
then an empty `GEOGRAPHY`

is returned.

See ST_INTERSECTS, ST_DISJOINT for related predicate functions.

**Return type**

`GEOGRAPHY`

### ST_SNAPTOGRID

```
ST_SNAPTOGRID(geography_expression, grid_size)
```

**Description**

Returns the input `GEOGRAPHY`

, where each vertex has
been snapped to a longitude/latitude grid. The grid size is determined by the
`grid_size`

parameter which is given in degrees.

**Constraints**

Arbitrary grid sizes are not supported. The `grid_size`

parameter is rounded so
that it is of the form $$10^n$$, where $$-10 < n < 0$$.

**Return type**

`GEOGRAPHY`

### ST_UNION

```
ST_UNION(geography_1, geography_2)
```

```
ST_UNION(array_of_geography)
```

**Description**

Returns a `GEOGRAPHY`

that represents the point set
union of all input `GEOGRAPHY`

s.

Input can either be two `GEOGRAPHY`

s or an
`ARRAY`

of type `GEOGRAPHY`

.

See `ST_UNION_AGG`

for the aggregate version of `ST_UNION`

.

**Return type**

`GEOGRAPHY`

### ST_CONTAINS

```
ST_CONTAINS(geography_1, geography_2)
```

**Description**

Returns `TRUE`

if no point of `geography_2`

is outside `geography_1`

, and
the interiors intersect; returns `FALSE`

otherwise.

NOTE: A `GEOGRAPHY`

*does not* contain its own
boundary. Compare with `ST_COVERS`

.

**Return type**

`BOOL`

**Example**

The following query tests whether the polygon `POLYGON((1 1, 20 1, 10 20, 1 1))`

contains each of the three points `(0, 0)`

, `(1, 1)`

, and `(10, 10)`

, which lie
on the exterior, the boundary, and the interior of the polygon respectively.

```
SELECT
ST_GEOGPOINT(i, i) AS p,
ST_CONTAINS(ST_GEOGFROMTEXT('POLYGON((1 1, 20 1, 10 20, 1 1))'),
ST_GEOGPOINT(i, i)) AS `contains`
FROM UNNEST([0, 1, 10]) AS i;
+--------------+----------+
| p | contains |
+--------------+----------+
| POINT(0 0) | false |
| POINT(1 1) | false |
| POINT(10 10) | true |
+--------------+----------+
```

### ST_COVEREDBY

```
ST_COVEREDBY(geography_1, geography_2)
```

**Description**

Returns `FALSE`

if `geography_1`

or `geography_2`

is empty.
Returns `TRUE`

no points of `geography_1`

lie in the exterior of `geography_2`

.

Given two `GEOGRAPHY`

s `a`

and `b`

,
`ST_COVEREDBY(a, b)`

returns the same result as
`ST_COVERS`

`(b, a)`

. Note the opposite order of arguments.

**Return type**

`BOOL`

### ST_COVERS

```
ST_COVERS(geography_1, geography_2)
```

**Description**

Returns `FALSE`

if `geography_1`

or `geography_2`

is empty.
Returns `TRUE`

if no points of `geography_2`

lie in the exterior of `geography_1`

.

**Return type**

`BOOL`

**Example**

The following query tests whether the polygon `POLYGON((1 1, 20 1, 10 20, 1 1))`

covers each of the three points `(0, 0)`

, `(1, 1)`

, and `(10, 10)`

, which lie
on the exterior, the boundary, and the interior of the polygon respectively.

```
SELECT
ST_GEOGPOINT(i, i) AS p,
ST_COVERS(ST_GEOGFROMTEXT('POLYGON((1 1, 20 1, 10 20, 1 1))'),
ST_GEOGPOINT(i, i)) AS `covers`
FROM UNNEST([0, 1, 10]) AS i;
+--------------+--------+
| p | covers |
+--------------+--------+
| POINT(0 0) | false |
| POINT(1 1) | true |
| POINT(10 10) | true |
+--------------+--------+
```

### ST_DISJOINT

```
ST_DISJOINT(geography_1, geography_2)
```

**Description**

Returns `TRUE`

if the intersection of `geography_1`

and `geography_2`

is empty,
that is, no point in `geography_1`

also appears in `geography_2`

.

`ST_DISJOINT`

is the logical negation of `ST_INTERSECTS`

.

**Return type**

`GEOGRAPHY`

### ST_DWITHIN

```
ST_DWITHIN(geography_1, geography_2, distance[, spheroid=FALSE])
```

**Description**

Returns `TRUE`

if the distance between at least one point in `geography_1`

and
one point in `geography_2`

is less than or equal to the distance given by the
`distance`

argument; otherwise, returns `FALSE`

. If either input
`GEOGRAPHY`

is empty, `ST_DWithin`

returns `FALSE`

. The
given `distance`

is in meters on the surface of the Earth.

The `spheroid`

parameter determines how distance is measured for this function.
If `spheroid`

is set to `FALSE`

, then distance is measured on the surface of a
perfect sphere. If `spheroid`

is set to `TRUE`

, distance is measured on the
surface of the WGS84 spheroid. The default for the `spheroid`

parameter is `FALSE`

.

**Return type**

`BOOL`

### ST_EQUALS

```
ST_EQUALS(geography_1, geography_2)
```

**Description**

Returns `TRUE`

if `geography_1`

and `geography_2`

represent the same
`GEOGRAPHY`

value. More precisely, this means that
one of the following conditions holds:

`ST_COVERS(geography_1, geography_2) = TRUE`

and`ST_COVERS(geography_2, geography_1) = TRUE`

- Both
`geography_1`

and`geography_2`

are empty.

Therefore, two `GEOGRAPHY`

s may be equal even if the
ordering of points or vertices differ, as long as they still represent the same
geometric structure.

**Constraints**

`ST_EQUALS`

is not guaranteed to be a transitive function.

**Return type**

`BOOL`

### ST_INTERSECTS

```
ST_INTERSECTS(geography_1, geography_2)
```

**Description**

Returns `TRUE`

if the point set intersection of `geography_1`

and `geography_2`

is non-empty. Thus, this function returns `TRUE`

if there is at least one point
that appears in both input `GEOGRAPHY`

s.

If `ST_INTERSECTS`

returns `TRUE`

, it implies that `ST_DISJOINT`

returns `FALSE`

.

**Return type**

`BOOL`

### ST_INTERSECTSBOX

```
ST_INTERSECTSBOX(geography, lng1, lat1, lng2, lat2)
```

**Description**

Returns `TRUE`

if `geography`

intersects the rectangle between `[lng1, lng2]`

and `[lat1, lat2]`

. The edges of the rectangle follow constant lines of
longitude and latitude. `lng1`

and `lng2`

specify the minimum and maximum
longitude lines that bound the rectangle, and `lat1`

and `lat2`

specify the
minimum and maximum constant latitude lines that bound the rectangle.

Specify all longitude and latitude arguments in degrees.

**Constraints**

The input arguments are subject to the following constraints:

- Latitudes should be in the
`[-90, 90]`

degree range. - Longitudes should be in the
`[-180, 180]`

degree range.

**Return type**

`BOOL`

### ST_TOUCHES

```
ST_TOUCHES(geography_1, geography_2)
```

**Description**

Returns `TRUE`

provided the following two conditions are satisfied:

`geography_1`

intersects`geography_2`

.- The interior of
`geography_1`

and the interior of`geography_2`

are disjoint.

**Return type**

`BOOL`

### ST_WITHIN

```
ST_WITHIN(geography_1, geography_2)
```

**Description**

Returns `TRUE`

if no point of `geography_1`

is outside of `geography_2`

and
the interiors of `geography_1`

and `geography_2`

intersect.

Given two geographies `a`

and `b`

, `ST_WITHIN(a, b)`

returns the same result
as `ST_CONTAINS`

`(b, a)`

. Note the opposite order of arguments.

**Return type**

`BOOL`

### ST_ISEMPTY

```
ST_ISEMPTY(geography_expression)
```

**Description**

Returns `TRUE`

if the given `GEOGRAPHY`

is empty;
that is, the `GEOGRAPHY`

does not contain any points,
lines, or polygons.

NOTE: A BigQuery empty `GEOGRAPHY`

is not
associated with a particular geometry shape. For example, the results of
expressions `ST_GEOGFROMTEXT('POINT EMPTY')`

and
`ST_GEOGFROMTEXT('GEOMETRYCOLLECTION EMPTY')`

are identical.

**Return type**

`BOOL`

### ST_ISCOLLECTION

```
ST_ISCOLLECTION(geography_expression)
```

**Description**

Returns `TRUE`

if the total number of points, linestrings, and polygons is
greater than one.

An empty `GEOGRAPHY`

is not a collection.

**Return type**

`BOOL`

### ST_DIMENSION

```
ST_DIMENSION(geography_expression)
```

**Description**

Returns the dimension of the highest-dimensional element in the input
`GEOGRAPHY`

.

The dimension of each possible element is as follows:

- The dimension of a point is
`0`

. - The dimension of a linestring is
`1`

. - The dimension of a polygon is
`2`

.

If the input `GEOGRAPHY`

is empty, `ST_DIMENSION`

returns `-1`

.

**Return type**

`INT64`

### ST_NUMPOINTS

```
ST_NUMPOINTS(geography_expression)
```

**Description**

Returns the number of vertices in the input
`GEOGRAPHY`

. This includes the number of points, the
number of linestring vertices, and the number of polygon vertices.

NOTE: The first and last vertex of a polygon ring are counted as distinct vertices.

**Return type**

`INT64`

### ST_AREA

```
ST_AREA(geography_expression[, spheroid=FALSE])
```

**Description**

Returns the area in square meters covered by the polygons in the input
`GEOGRAPHY`

.

If `geography_expression`

is a point or a line, returns zero. If
`geography_expression`

is a collection, returns the area of the polygons in the
collection; if the collection does not contain polygons, returns zero.

If `spheroid`

is set to `FALSE`

, the area of the input is measured on the
surface of a perfect sphere; if `TRUE`

, the area is measured on the surface of
the WGS84 spheroid. The default for the `spheroid`

parameter is
`FALSE`

.

**Return type**

`FLOAT64`

### ST_DISTANCE

```
ST_DISTANCE(geography_1, geography_2[, spheroid=FALSE])
```

**Description**

Returns the shortest distance in meters between two non-empty
`GEOGRAPHY`

s.

If either of the input `GEOGRAPHY`

s is empty,
`ST_DISTANCE`

returns `NULL`

.

If `spheroid`

is set to `FALSE`

, distance is measured on the surface of a
perfect sphere; if `TRUE`

, distance is measured on the surface of the
WGS84 spheroid. The default for the `spheroid`

parameter is
`FALSE`

.

**Return type**

`FLOAT64`

### ST_LENGTH

```
ST_LENGTH(geography_expression[, spheroid=FALSE])
```

**Description**

Returns the total length in meters of the lines in the input
`GEOGRAPHY`

.

If `geography_expression`

is a point or a polygon, returns zero. If
`geography_expression`

is a collection, returns the length of the lines in the
collection; if the collection does not contain lines, returns zero.

If `spheroid`

is set to `FALSE`

, the length of the input is measured on the
surface of a perfect sphere; if `TRUE`

, the length is measured on the surface
of the WGS84 spheroid. The default for the `spheroid`

parameter is
`FALSE`

.

**Return type**

`FLOAT64`

### ST_MAXDISTANCE

```
ST_MAXDISTANCE(geography_1, geography_2[, spheroid=FALSE])
```

Returns the longest distance in meters between two non-empty
`GEOGRAPHY`

s; that is, the distance between two
vertices where the first vertex is in the first
`GEOGRAPHY`

, and the second vertex is in the second
`GEOGRAPHY`

. If `geography_1`

and `geography_2`

are the
same `GEOGRAPHY`

, the function returns the distance
between the two most distant vertices in that
`GEOGRAPHY`

.

If either of the input `GEOGRAPHY`

s is empty,
`ST_MAXDISTANCE`

returns `NULL`

.

If `spheroid`

is set to `FALSE`

, distance is measured on the surface of a
perfect sphere; if `TRUE`

, distance is measured on the surface of the
WGS84 spheroid. The default for the `spheroid`

parameter is
`FALSE`

.

**Return type**

`FLOAT64`

### ST_PERIMETER

```
ST_PERIMETER(geography_expression[, spheroid=FALSE])
```

**Description**

Returns the length in meters of the boundary of the polygons in the input
`GEOGRAPHY`

.

If `geography_expression`

is a point or a line, returns zero. If
`geography_expression`

is a collection, returns the perimeter of the polygons
in the collection; if the collection does not contain polygons, returns zero.

If `spheroid`

is set to `FALSE`

, the length of the input is measured on the
surface of a perfect sphere; if `TRUE`

, distance is measured on the surface of
the WGS84 spheroid. The default for the `spheroid`

parameter is
`FALSE`

.

**Return type**

`FLOAT64`

### ST_UNION_AGG

```
ST_UNION_AGG(geography)
```

Returns a `GEOGRAPHY`

that represents the point set
union of all input `GEOGRAPHY`

s.

See `ST_UNION`

for the non-aggregate version of `ST_UNION_AGG`

.

**Return type**

`GEOGRAPHY`