使用postgreSQL和PostGIS查询空间相交（点-列中的多边形）

Question

I'm trying to figure out how to create a query, which asks for points within a polygon. My setup is a postgreSQL 9.5 instance with a installed PostGIS 2.2.2 extension. Theoretically this might not be really difficult as it is shown in the PostGIS documentation , but I am not able to get any result.

I've created the following table:

CREATE TABLE app_db.testTable
(
  message_text text,
  message_picture text,
  message_date timestamp with time zone DEFAULT now(),
  message_id uuid NOT NULL DEFAULT uuid_generate_v4(),
  message_position app_db.geometry,
  message_radius integer,
  message_circle app_db.geometry,
  message_userid uuid,
  CONSTRAINT messages_pkey PRIMARY KEY (message_id)
)

I've enabled PostGIS with the following command for my schemata:

CREATE EXTENSION postgis SCHEMA app_db;

And I've put some example datasets in the above mentioned table. So far so good.

Not I'm trying to create a query, which should ask for all data, where the defined point intersects one of the geometries stored in my table column app_db -> message.circle : As far as I've understood ST_Intersects needs two geometries as parameters, but how do I perform a query in regard to a complete column?

Answer 1

Note that normally folks install postgis into public and/or have the installed schema on the search_path so you don't need to provide full paths like app_db.ST_Intersects . For the examples below, I'm assuming SET search_path TO app_db; to make it simpler.

To select all the points in message_position from a single polygon in message_circle :

SELECT p.*
FROM testTable p
JOIN testTable c ON c.message_id='the id of the circle'
    AND p.message_id <> c.message_id
    AND ST_Intersects(p.message_position, c.message_circle);

I'm not sure how message_circle was made, but if it was created from message_position and message_radius , then a better way is to use ST_DWithin , which uses a distance threshold, rather than a more expensive and imperfect geometry analysis.

SELECT p.*
FROM testTable p
JOIN testTable c ON c.message_id='the id of the circle'
    AND p.message_id <> c.message_id
    AND ST_DWithin(p.message_position, c.message_position, c.message_radius);

It can be sped up by creating a GiST spatial index on message_position .