h3

H3 is Uber’s Hexagonal Hierarchical Spatial Index. Full documentation of the project can be found at h3geo. You can also learn more about H3 in the Overview section of this documentation.

ST_ASH3

Description

Returns the H3 cell index that the point belongs to in the required resolution. It will return null on error (invalid geography type or resolution out of bounds).

  • point: GEOGRAPHY point to get the H3 cell from.
  • resolution: INT64 number between 0 and 15 with the H3 resolution.

Return type

STRING

Example

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SELECT bqcarto.h3.ST_ASH3(ST_GEOGPOINT(40.4168, -3.7038), 4);
-- 847b59dffffffff

LONGLAT_ASH3

Description

Returns the H3 cell index that the point belongs to in the required resolution. It will return null on error (resolution out of bounds).

  • longitude: FLOAT64 horizontal coordinate of the map.
  • latitude: FLOAT64 vertical coordinate of the map.
  • resolution: INT64 number between 0 and 15 with the H3 resolution.

Return type

STRING

Example

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SELECT bqcarto.h3.LONGLAT_ASH3(40.4168, -3.7038, 4);
-- 847b59dffffffff

ST_ASH3_POLYFILL

Description

Returns an array with all the H3 cell indexes with centers contained in a given polygon. It will return null on error (invalid geography type or resolution out of bounds).

  • geography: GEOGRAPHY polygon or multipolygon representing the area to cover.
  • resolution: INT64 number between 0 and 15 with the H3 resolution.

Return type

ARRAY<STRING>

Example

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SELECT bqcarto.h3.ST_ASH3_POLYFILL(
    ST_GEOGFROMTEXT("POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))"), 4);
-- 846b26bffffffff
-- 843e8b1ffffffff
-- 842d1e5ffffffff
-- 843ece5ffffffff
-- ...

ST_BOUNDARY

Description

Returns a geography representing the H3 cell. It will return null on error (invalid input).

  • index: STRING The H3 cell index.

Return type

GEOGRAPHY

Example

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SELECT bqcarto.h3.ST_BOUNDARY("847b59dffffffff");
-- POLYGON((40.4650636223452 -3.9352772457965, 40.5465406026705 ...

ISVALID

Description

Returns true when the given index is valid, false otherwise.

  • index: STRING The H3 cell index.

Return type

BOOLEAN

Examples

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SELECT bqcarto.h3.ISVALID("847b59dffffffff");
-- true
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SELECT bqcarto.h3.ISVALID("1");
-- false

COMPACT

Description

Returns an array with the indexes of a set of hexagons across multiple resolutions that represent the same area as the input set of hexagons.

  • indexArray: ARRAY<STRING> of H3 cell indices of the same resolution.

Return type

ARRAY<STRING>

Example

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SELECT bqcarto.h3.COMPACT(["857b59c3fffffff", "857b59c7fffffff", "857b59cbfffffff","857b59cffffffff", "857b59d3fffffff", "857b59d7fffffff", "857b59dbfffffff"]);
-- 847b59dffffffff

UNCOMPACT

Description

Returns an array with the indexes of a set of hexagons of the same resolution that represent the same area as the compacted input hexagons.

  • indexArray: ARRAY<STRING> of H3 cell indices.
  • resolution: INT64 number between 0 and 15 with the H3 resolution.

Return type

ARRAY<STRING>

Example

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SELECT bqcarto.h3.UNCOMPACT(["847b59dffffffff"], 5);
-- 857b59c3fffffff
-- 857b59c7fffffff
-- 857b59cbfffffff
-- 857b59cffffffff
-- 857b59d3fffffff
-- 857b59d7fffffff
-- 857b59dbfffffff

TOPARENT

Description

Returns the H3 cell index of the parent of the given hexagon at the given resolution.

  • index: STRING The H3 cell index.
  • resolution: INT64 number between 0 and 15 with the H3 resolution.

Return type

STRING

Example

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SELECT bqcarto.h3.TOPARENT("847b59dffffffff", 3);
-- 837b59fffffffff

TOCHILDREN

Description

Returns an array with the indexes of the children/descendents of the given hexagon at the given resolution.

  • index: STRING The H3 cell index.
  • resolution: INT64 number between 0 and 15 with the H3 resolution.

Return type

ARRAY<STRING>

Example

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SELECT bqcarto.h3.TOCHILDREN("837b59fffffffff", 4);
-- 847b591ffffffff
-- 847b593ffffffff
-- 847b595ffffffff
-- 847b597ffffffff
-- 847b599ffffffff
-- 847b59bffffffff
-- 847b59dffffffff

ISPENTAGON

Description

Returns true if given H3 index is a pentagon. Returns false otherwise, even on invalid input.

  • index: STRING The H3 cell index.

Return type

BOOLEAN

Example

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SELECT bqcarto.h3.ISPENTAGON("837b59fffffffff");
-- false

DISTANCE

Description

Returns the grid distance between two hexagon indexes. This function may fail to find the distance between two indexes if they are very far apart or on opposite sides of a pentagon. Returns null on failure or invalid input.

  • origin: STRING origin H3 cell index.
  • destination: STRING destination H3 cell index.

Return type

INT64

Example

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SELECT bqcarto.h3.DISTANCE("847b591ffffffff", "847b59bffffffff");
-- 1

KRING

Description

Returns an array with the indexes of all hexagons within distance of the given input hexagon. The order of the hexagons is undefined. Returns null on invalid input.

  • index: STRING The H3 cell index.
  • distance: INT64 distance (in number of cells) to the source.

Return type

ARRAY<STRING>

Example

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SELECT bqcarto.h3.KRING("837b59fffffffff", 1);
-- 837b59fffffffff
-- 837b58fffffffff
-- 837b5bfffffffff
-- 837a66fffffffff
-- 837a64fffffffff
-- 837b4afffffffff
-- 837b5dfffffffff

HEXRING

Description

Get all hexagons in a hollow hexagonal ring centered at origin with sides of a given length. Unlike KRING, this function will return null if there is a pentagon anywhere in the ring.

  • index: STRING The H3 cell index.
  • distance: INT64 distance (in cells) to the source.

Return type

ARRAY<STRING>

Example

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SELECT bqcarto.h3.HEXRING("837b59fffffffff", 1);
-- 837b5dfffffffff
-- 837b58fffffffff
-- 837b5bfffffffff
-- 837a66fffffffff
-- 837a64fffffffff
-- 837b4afffffffff

VERSION

Description

Returns the current version of the H3 module.

Return type

STRING

Example

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SELECT bqcarto.h3.VERSION();
-- 3.7.0.1