ClickHouse LineString Type: Representing Paths with Arrays of Points

  

When working with geospatial data, it's important to represent not just areas (polygons) but also paths, routes, or edges. That’s where the LineString type comes in. ClickHouse supports LineString as a simple way to store a line made up of multiple points, very useful for roads, or movement paths.

 

What is a LineString?

A LineString is a series of connected points, forming a line, like a route on a map.

 

LineString Characterstics

·      Internally stored as Array(Point)

·      A Point is a pair of coordinates (x, y)

·      Unlike Ring, it does not close back to the starting point

 

Let’s take a real world example to understand LineString better.

CREATE DATABASE IF NOT EXISTS demo_db;

CREATE TABLE demo_db.road_paths (
    road_name String,
    path LineString
) ENGINE = Memory();

   

Here:

·      road_name: Name of the road or route

·      path: A LineString (series of points forming a path)

 

Let’s define a road that makes 3 turns.

From (0,0) → (10,0) → (10,10) → (0,10)

 

INSERT INTO demo_db.road_paths VALUES
(
    'Main Street',
    [(0, 0), (10, 0), (10, 10), (0, 10)]
);

   

Let's view the line string.

 

SELECT
    road_name,
    path,
    toTypeName(path) AS type
FROM demo_db.road_paths;

krishna :) SELECT
    road_name,
    path,
    toTypeName(path) AS type
FROM demo_db.road_paths;

SELECT
    road_name,
    path,
    toTypeName(path) AS type
FROM demo_db.road_paths

Query id: f57ba1aa-4e68-4d93-a4d3-9718b87f6429

   ┌─road_name───┬─path──────────────────────────┬─type───────┐
1. │ Main Street │ [(0,0),(10,0),(10,10),(0,10)] │ LineString │
   └─────────────┴───────────────────────────────┴────────────┘

1 row in set. Elapsed: 0.001 sec.

 

 

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