Simple explanation of how nested sets work and how to perform some basic tasks on them

1. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

2. •
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•
•
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JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

3. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Eli Aschkenasy
I LOVE
DATA!

4. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Eli Aschkenasy
 Lived in 7 countries
 Live for Skiing/Kayaking
 Love! Data
 Like Joomla!
DATA
I LOVE
DATA!

5. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Eli Aschkenasy
I LOVE
JOOMLA!

6. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Eli Aschkenasy
 Lived in 7 countries
 Live for Skiing/Kayaking
 Like Data
 Love Joomla!
JOOMLA

7. • WHO AM I ?
•
•
•
•
•
•
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

8. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

9. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

10. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

11. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

12. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

13. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
ROOT NODE
root - lft = 1
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

14. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
TOTAL NODES
(rgt – lft + 1) / 2 = total
(36 – 1 + 1) / 2 = 18
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

15. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
IS LEAF NODE?
leaf = (rgt – lft ==1) ? true : false;
true = (5 – 4 == 1)
false = (8 – 3 == 1)
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

16. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
LEAF NODE OPTIMIZATION
Naïve implementation
SELECT *
FROM #__
WHERE rgt – lft = 1
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

17. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
LEAF NODE OPTIMIZATION
Normal implementation
SELECT *
FROM #__
WHERE lft = (rgt -1)
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

18. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
LEAF NODE OPTIMIZATION
Optimized implementation
SELECT x, x, x
FROM #__
WHERE lft = (rgt -1)
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

19. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
SUBTREE SELECTION
Schoolbook implementation
SELECT c.type AS choices, b.type AS
bottom
FROM #__ AS c, #__ AS b
WHERE c.lft BETWEEN b.lft AND b.rgt
AND c.rgt BETWEEN b.lft AND b.rgt;
Anything between 22 and 35
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

20. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
SUBTREE SELECTION OPTIMIZATION
Naïve implementation
SELECT c.type AS choices, b.type AS
bottom
FROM #__ AS c, #__ AS b
WHERE c.lft BETWEEN b.lft AND b.rgt;
Anything between 22 and 35
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

21. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
SUBTREE SELECTION ONLY SUBTREE
Naïve implementation
SELECT c.type AS choices, b.type AS
bottom
FROM #__ AS c, #__ AS b
WHERE c.lft BETWEEN b.lft AND b.rgt
AND c.lft <> b.lft;
Anything between 22 and 35 and isn’t 22
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

22. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
SUBTREE SELECTION ONLY SUBTREE
Optimized implementation
SELECT c.type AS choices, b.type AS
bottom
FROM #__ AS c, #__ AS b
WHERE c.lft BETWEEN (b.lft+1) AND b.rgt;
Anyone between 23and 35
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

23. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

24. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
PATH TO A NODE
SELECT alias
FROM #__
WHERE lft < 4 AND rgt > 5
ORDER BY lft ASC;
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

25. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
PATH TO A NODE
Including leaf node
SELECT alias
FROM #__
WHERE lft < 5 AND rgt > 4
ORDER BY lft ASC;
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

26. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
PATH TO A NODE
SELECT alias
FROM #__
WHERE lft < 27 AND rgt > 26
ORDER BY lft ASC;
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

27. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
LEVEL OF NODE
SELECT b.id, COUNT(a.id) AS level
FROM #__ AS a, #__ AS b
WHERE b.lft BETWEEN a.lft AND a.rgt
GROUP BY b.id
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

28. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
MAXIMUM DEPTH
SELECT MAX(level) AS height
FROM (
SELECT b.id, (COUNT(a.id) - 1) AS level
FROM #__ AS a, #__ AS b
WHERE b.lft BETWEEN a.lft AND a.rgt
GROUP BY b.id
) AS L1
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

29. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
PARENT ID OF A NODE
SELECT id, (SELECT id
FROM #__ t2
WHERE t2.lft < t1.lft AND t2.rgt > t1.rgt
ORDER BY t2.rgt-t1.rgt ASC
LIMIT 1)
AS parent FROM #__ t1
ORDER BY (rgt-lft) DESC
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

30. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
INSERT A NODE
UPDATE #__ SET rgt=rgt+2 WHERE rgt >= 25;
UPDATE #__ SET lft=lft+2 WHERE lft >= 24;
INSERT INTO #__ SET lft=24, rgt=25, ….;
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

31. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
5
2
3
2
8
2
4
2
5
2
6
2
7
2
9
3
4
3
0
3
2
3
1
3
3
3
6
INSERT A NODE
UPDATE #__ SET rgt=rgt+2 WHERE rgt >= 25;
UPDATE #__ SET lft=lft+2 WHERE lft >= 24;
INSERT INTO #__ SET lft=24, rgt=25, ….;
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

32. Root Node
1
2
3
4 5
lft rgt
1 36
2 15
3 8
4 5
6 7
9 14
10 11
12 13
16 21
17 18
19 20
22 35
23 28
24 25
26 27
29 34
30 31
32 33
6 7
8 9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
2
1
2
2
3
7
2
3
3
0
2
6
2
7
2
8
2
9
3
1
3
6
3
2
3
4
3
3
3
5
3
8
INSERT A NODE
UPDATE #__ SET rgt=rgt+2 WHERE rgt >= 25;
UPDATE #__ SET lft=lft+2 WHERE lft >= 24;
INSERT INTO #__ SET lft=24, rgt=25, ….;
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
2
4
2
5

33. • WHO AM I ?
• NESTED SET INTRO
• NESTED SET BASIC QUERIES
• NESTED SET BASIC QUERIES OPTIMIZATION
•
•
•
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

34. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

35. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Common INSERT
INSERT INTO #__ (part_number, unit_price,
eau,….)
VALUES (….);
Common SELECT
SELECT unit_price FROM #__
WHERE part_number = $part_number;

36. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Common INSERT
INSERT INTO #__ (part_number, unit_price,
eau,….)
VALUES (….);
Common SELECT
SELECT unit_price FROM #__
WHERE part_number = $part_number;
PROBLEMS:
1. Speed
2. Data accuracy (inconsistent white spacing)

37. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Amended INSERT
php: $concat = preg_replace('/s+/', '', $input);
INSERT INTO #__ (part_number, unit_price,
eau,part_number_concat,…)
VALUES (…,$concat);
Amended SELECT
SELECT unit_price FROM #__
WHERE part_number_concat = $concat;
PROBLEMS:
1. Speed
2. Data accuracy (inconsistent white spacing)

38. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Optimized INSERT
php: $concat = preg_replace('/s+/', '', $input);
php: $crc = crc32($concat);
INSERT INTO #__ (part_number, unit_price,
eau,part_number_concat,crc_partnumberconcat…)
VALUES (…,$concat,$crc);
Optimized SELECT
SELECT unit_price FROM #__
WHERE crc_partnumberconcat = $crc
AND part_number_concat = $concat; (singularity)
PROBLEMS:
1. Speed
2. Data accuracy (inconsistent white spacing)

39. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Optimized INSERT (* BATCH)
php: $concat = preg_replace('/s+/', '', $input);
php: $crc = crc32($concat);
ALTER TABLE #__ DROP INDEX x
INSERT INTO #__ (part_number, unit_price,
eau,part_number_concat,crc_partnumberconcat…)
VALUES (…,$concat,$crc);
ALTER TABLE #__ ADD INDEX x (‘column’)
Optimized SELECT
SELECT unit_price FROM #__
WHERE crc_partnumberconcat = $crc
AND part_number_concat = $concat;
PROBLEMS:
1. Speed
2. Data accuracy (inconsistent white spacing)

40. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Indexing Options
ALWAYS BENCHMARK (against COLD DB)

41. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles
Indexing Options
ALWAYS BENCHMARK (against COLD DB)
USE EXPLAIN (EXTENSIVELY!!!)
Assumption:
I might search part_number_concat directly:
idx_pnc_crc (part_number_concat, crc_partnumberconcat)
Alternative:
idx_crc_pnc (crc_partnumberconcat, part_number_concat)
idx_pnc (part_number_concat)

42. • WHO AM I ?
• NESTED SET INTRO
• NESTED SET BASIC QUERIES
• NESTED SET BASIC QUERIES OPTIMIZATION
• STRING LOOKUP OPTIMIZATION TRICK
• INDEXING OPTIONS
•
JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

43. •
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JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles

44. JWC13 - Eli Aschkenasy - Nested Sets & DB Design Principles