Choosing data structure/storage solution for complex geo queries - postgresql

Question

I have a dataset of entities with their type and lat/long. Like this:
Name Type Lat Long
House1 Big 1 2
House11 Bigger 2 2
House12 Biggest 3 2
House13 Small 4 2
House14 Medium 5 2
So these are houses with their type and location. Now I need to answer queries like: "Find all house of type Big which have a Small and a Medium house in its 10km radius"
What kind of data structure/storage solution would be right here? I looked at Elasticsearch and Redis but looks like I need to iterate over all the houses of the given type (Big for the sample query above) to answer this.

Answer 1

It's perfectly feasible directly from PostgreSQL with PostGIS.
Considering your table structure ...
CREATE TEMPORARY TABLE t (name TEXT, type TEXT, geom GEOGRAPHY);
... and your test data ...
INSERT INTO t VALUES ('House1','Big', ST_MakePoint(1,2));
INSERT INTO t VALUES ('House11','Bigger', ST_MakePoint(2,2));
INSERT INTO t VALUES ('House12','Biggest', ST_MakePoint(3,2));
INSERT INTO t VALUES ('House13','Small', ST_MakePoint(4,2));
INSERT INTO t VALUES ('House14','Medium', ST_MakePoint(5,2));
(Note: here makes no sense to split lat,long in different columns. PostGIS can store both in a single GEOGRAPHY or GEOMETRY column. See ST_MakePoint for more details.)
"Find all house of type Big which have a Small and a Medium house in
its 10km radius"
Try something like this using ST_Distance:
WITH j AS (SELECT * FROM t WHERE type = 'Big')
SELECT
j.name,j.type,
ST_Distance(j.geom,t.geom) AS distance,
t.name, t.type
FROM j,t
WHERE
ST_Distance(j.geom,t.geom) > 10000 AND
t.type IN ('Small','Medium');
name | type | distance | name | type
--------+------+-----------------+---------+--------
House1 | Big | 333756.3481116 | House13 | Small
House1 | Big | 445008.41595616 | House14 | Medium
(2 Zeilen)
(This query returns records which are more than 10k meters away from the Big type house. Just adapt the first where statement to your needs)
EDIT: Query based on the comments.
WITH j AS (SELECT *, ARRAY(SELECT DISTINCT t2.type
FROM t t2
WHERE t2.type IN ('Small','Medium') AND
ST_Distance(t2.geom,t1.geom) < 100000
) AS nearHouseType
FROM t t1 WHERE type = 'Big')
SELECT *
FROM j
WHERE j.nearHouseType #> '{Medium, Small}'::TEXT[]