Store multidimensional array in database: relational or multidimensional?

Question

I have read numerous posts along the lines of multidimensional to single dimension, multidimensional database, and so on, but none of the answers helped. I did

Answer 1

For your scenario, I would suggest you to use Nested Sets Approach in PostgreSQL. It is XML tags based querying using Relational database.

Performance

If you index on lft and rgt columns, then you don't require recursive queries to get the data. Even though, the data seems huge, the retrieval will be very fast.

Sample

/*1A:
2  AA:
3    AAA
4    AAC
5  AB
6  AE:
7   AEA
8   AEE:
9     AEEB
10B:
*/

CREATE TABLE tree(id int, CELL varchar(4), lft int, rgt int);
    
INSERT INTO tree
    ("id", CELL, "lft", "rgt")
VALUES
    (1, 'A', 1, 9),
    (2, 'AA', 2, 4),
    (3, 'AAA', 3, 3),
    (4, 'AAC', 4, 4),
    (5, 'AB', 5, 5),
    (6, 'AE', 6, 9),
    (7, 'AEA', 7, 7),
    (8, 'AEE', 8, 8),
    (9, 'AEEB', 9, 9)
;


SELECT  hc.*
FROM    tree hp
JOIN    tree hc
ON      hc.lft BETWEEN hp.lft AND hp.rgt
WHERE   hp.id = 2

Demo

Querying using Nested Sets approach