Find nearest points with MySQL from points Table

Question

I have a DB Schema like this (from this tutorial by Google) -

So the actual points in a graph for them is like this-

What I want is to find points near a given point (by point_id) point ordered by distance

Location of a point (x,y) is (point_x,point_y) in DB

I want to solve it with MySQL because my DB is already in MySQL.

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Update-

Finding distance of 2 points is so easy like this-

I want to sort on distance with MySQL.

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Re-

For removing the confusions, I want the points inside the circle, later. But now I want to find only the sorted points.

So u can ignore the circles.

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I don't have any idea how to do it, can anyone please help?

Haphtarah

How would you define nearest points? – Walkling

It is a common question to find distance between 2 points, it is given in updated question – Haphtarah

I didn't ask for that. You marked a circle. Probably you want all those points inside the circle. That's why I asked what's your criteria to grab those points? – Walkling

Yes, I want the points inside the circle, later. But now I want to find only the sorted points – Haphtarah

Question updated for your kind info. – Haphtarah

Answer 1

I have found a better solution than @1000111 's solution.

There is custom DB type in MySQL for this kind of data which gives a better performance.

OpenGIS in MySQL is perfect for this.

Functions are given here.

An illustrative definition is given in this StackOverflow question.

My solution is like this-

DB Table-

CREATE TABLE geoTable
(
    id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(30) NOT NULL,
    geoPoint POINT NOT NULL,
    SPATIAL INDEX(geoPoint)
) ENGINE=MyISAM;


INSERT INTO geoTable (name, geoPoint)
VALUES
  ( "A", GeomFromText('POINT(0.1 -1.01)') ),
  ( "B", ST_GeomFromText('POINT(56.31 2.81)') ),
  ( "C", ST_GeomFromText('POINT(11.1 1.176)') ),
  ( "ui", ST_GeomFromText('POINT(9.1 2.1)') );

SQL Query-

SELECT
  id,
  name,
  X(geoPoint) AS "latitude",
  Y(geoPoint) AS "longitude",
  (
    GLength(
      LineStringFromWKB(
        LineString(
          geoPoint, 
          GeomFromText('POINT(51.5177 -0.0968)')
        )
      )
    )
  )
  AS distance
FROM geoTable
  ORDER BY distance ASC;

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An example SQL Fiddle is given here.

See the execution time-

For 150 entry, it is only 13ms.

Haphtarah

Why the LineStringFromWKB ? Without it, the query runs fine with exactly same result – Cherida

If your table is very large, you might filter it using the MBRContains function, before sorting, as this can make use of SPATIAL indexes. – Eam

LineStringFromWKB Why use it? Can you please explain? – Classics

How about high dimensions? – Addi

ST_Distance( geoPoint , 'POINT(51.5177 -0.0968)' ) OR ST_Distance_Sphere( geoPoint , 'POINT(51.5177 -0.0968)' ) – Hayes

Answer 2

Try this query please [a straight forward approach]:

Suppose, you want to find the nearest 20 points of the point having point_id = 5

SET @givent_point_id := 5;

SELECT 
P1.point_id,
P1.point_name,
P1.point_x,
P1.point_y,
(POW(ABS((P2.point_x - P1.point_x)),2) + POW(ABS((P2.point_y - P1.point_y)),2)) AS sqr_distance
FROM Point P1,
    (SELECT point_x,point_y FROM Point WHERE point_id = @givent_point_id) P2
WHERE P1.point_id <> @givent_point_id
ORDER BY sqr_distance
LIMIT 20;

Demo Here

More: You may have a look at MySQL SPATIAL DATATYPE.

MySQL spatial indexes use R-tree as data structure which is specially designed for spatial access methods.

R-trees are tree data structures used for spatial access methods, i.e., for indexing multi-dimensional information such as geographical coordinates, rectangles or polygons.

Walkling

Sorry to say, I can't use this straight forward way. Because it is too slow and if the total points> 10000 then we can't expect an answer from this query – Haphtarah

Because it is server, so may be 1000 request comes in 1 sec and there may be 100000 points. SO this procedure will fail – Haphtarah

No, it is DB budy, so we have to apply some algo to find result in a efficient way, not this way – Haphtarah

Have you run this query? What's the execution time? You may share the Explain ... result of this query. @AbrarJahin – Walkling

There is only 4 points now, so u can't compare. Can compare if u have 10000 points or more. NP, let me try if there is any alternative, if not, I should have accept your answer. Thanks for your help – Haphtarah

I have found a better and efficient way for it – Haphtarah