Introduction to PostgreSQL path Data Type

PostgreSQL is a powerful relational database management system that supports various types of data. One interesting data type is path, which can store paths in two-dimensional planes, such as curves or polylines composed of multiple line segments. The path type was introduced in PostgreSQL version 8.0 and enhanced in version 9.4.

Syntax

The syntax for the path type is as follows:

path

The path data type can only be used for storing planar geometric paths. It consists of a set of points and line segments that represent the path.

The representation of a path is as follows:

((x1,y1), ...)

Where (x1,y1) represents the first point, and (...) represents the coordinates of other points.

Use Cases

The path data type is primarily used for representing planar geometric paths. It is applicable in many scenarios, such as:

• Storing routes or outlines on maps
• Storing paths of objects, such as the movement trajectories of robots or airplanes
• Storing the movement paths of living organisms, such as bird or fish migration paths

Examples

Example 1

In this example, we will create a table named path_demo with a column of type path named route. We will store some paths in this column and query for the start and end points of the paths.

CREATE TABLE path_demo (
    id SERIAL PRIMARY KEY,
    route path
);

INSERT INTO path_demo (route) VALUES ('((1,1),(2,2),(3,1))');
INSERT INTO path_demo (route) VALUES ('((0,0),(1,1),(1,2),(2,2))');

SELECT id, pointn(route,1) AS start_point, pointn(route, npoints(route)) AS end_point
FROM path_demo;

The result is:

 id | start_point | end_point
----+-------------+-----------
  1 | (1,1)       | (3,1)
  2 | (0,0)       | (2,2)

Example 2

In this example, we will create a table named room with a column of type path named outline. We will store the outline of a rectangle in this column and query for the area of the rectangle.

CREATE TABLE room (
    id SERIAL PRIMARY KEY,
    outline path
);

INSERT INTO room (outline) VALUES ('((0,0),(0,5),(10,5),(10,0),(0,0))');

SELECT id, abs(area(polygons(outline))) AS area FROM room;

The result is:

 id | area
----+------
  1 | 50.0

Conclusion

The path type is an interesting data type in PostgreSQL that can store planar geometric paths and be useful in many scenarios. Whether it is storing routes on maps or movement paths of robots, the path type is a handy tool. In this article, we have learned about the syntax and use cases of the path type and provided two detailed examples to demonstrate its usage.

It is important to note that when using the path type, certain syntax rules need to be followed. Specific functions and operators need to be used when creating and querying tables containing the path type. Also, due to the fact that the path type stores planar geometric paths, precision and data format issues should be considered when using it.

In conclusion, the path type is a powerful and useful data type in PostgreSQL that can provide us with many convenient functionalities. If you are dealing with data related to plane geometry paths, then the path type is a tool worth trying.