The document discusses guidelines for ordering fields in compound indexes to optimize query performance. It recommends the E-S-R approach: placing equality fields first, followed by sort fields, and range fields last. This allows indexes to leverage equality matches, provide non-blocking sorts, and minimize scanning. Examples show how indexes ordered by these guidelines can support queries more efficiently by narrowing the search bounds.

2. Tips and Tricks++ Querying For Indexing
Ben Perlmutter
Senior Solution Architect

3. Ben Perlmutter
Senior Solution Architect

4. Ben Perlmutter
Senior Solution Architect
I identified slow queries.
What index do I make?

5. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

6. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

7. Equality Sort Range "Rule"

8. E-S-R
Have you thought about the order of the fields in a compound index?

9. E-S-R
Have you thought about the order of the fields in a compound index?
Does it really matter?

10. E-S-R
Have you thought about the order of the fields in a compound index?
The ordering of index keys in a compound index is critically important.
E-S-R provides guidance that is useful in most cases:
• Equality first
• Sort next
• Range last

11. E-S-R
The ordering of index keys in a compound index is critically important.
E-S-R provides guidance that is useful in most cases:
• Equality first
• Sort next
• Range last
What is the difference between
Equality and Range?

12. Definitions
Equality Fields
An exact match on a single
value. For example:
• {x:123}
• {x:{$eq:123}}
• {"x.y":123}
Bounds:
"[123.0, 123.0]"

13. Definitions
Equality Fields Sort
The (entire) requested sort.
.sort({a:1, b:-1})
Bounds:
"[MinKey, MaxKey]",
"[MinKey, MaxKey]"
An exact match on a single
value. For example:
• {x:123}
• {x:{$eq:123}}
• {"x.y":123}
Bounds:
"[123.0, 123.0]"

14. Definitions
Equality Fields Sort Range Predicates
Any predicates that are not
exact matches. Some
operators include:
• {z:{$gt:9000}}
• {z:{$lte:1000}}
Bounds:
"[9000.0, inf.0]",
The (entire) requested sort.
.sort({a:1, b:-1})
Bounds:
"[MinKey, MaxKey]",
"[MaxKey, MinKey]"
An exact match on a single
value. For example:
• {x:123}
• {x:{$eq:123}}
• {"x.y":123}
Bounds:
"[123.0, 123.0]"

15. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

16. Equality
Equality keys are placed first in any order
If present in the query shape,
equality fields should always form the prefix for the index.

17. Equality
Equality keys are placed first in any order
If present in the query shape,
equality fields should always form the prefix for the index.
Why?

18. Equality
Equality keys are placed first in any order
If present in the query shape,
equality fields should always form the prefix for the index.
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )

19. Equality
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
If present in the query shape,
equality fields should always form the prefix for the index.
Equality keys are placed first in any order

20. db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
Equality
{gamertag: "Ace", score: 100}
{gamertag: "Ace", score: 99,999}
{gamertag: "Bob", score: 15,000}
{gamertag: "Bob", score: 50,000}

21. db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {}
{}{}
100 15,000 50,000 99,999
Ace Bob Bob Ace
{gamertag: "Ace", score: 100}
{gamertag: "Ace", score: 99,999}
{gamertag: "Bob", score: 15,000}
{gamertag: "Bob", score: 50,000}
Equality

22. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
db.games.createIndex({score:1, gamertag:1})

23. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
db.games.createIndex({score:1, gamertag:1})

24. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

25. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

26. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

27. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

28. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

29. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

30. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

31. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

32. 100 15,000 50,000 99,999
Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality

33. Ace Bob Bob Ace
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
100 99,999 15,000 50,000
{} {} {} {}
Equality

34. 100
Ace Bob
99,999 15,000 50,000
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"(9000.0, inf.0]"
],
}
db.games.createIndex({gamertag:1, score:1})

35. 100
Ace Bob
99,999 15,000 50,000
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"(9000.0, inf.0]"
],
}
gamertag
db.games.createIndex({gamertag:1, score:1})

36. 100
Ace Bob
99,999 15,000 50,000
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"(9000.0, inf.0]"
],
}
gamertag
score
db.games.createIndex({gamertag:1, score:1})

37. 100
Ace Bob
99,999 15,000 50,000
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"(9000.0, inf.0]"
],
}
gamertag
score
db.games.createIndex({gamertag:1, score:1})

38. 100
Ace Bob
99,999 15,000 50,000
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"(9000.0, inf.0]"
],
}
gamertag
score
db.games.createIndex({gamertag:1, score:1})

39. 100
Ace Bob
99,999 15,000 50,000
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
{} {} {} {}
Equality
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"(9000.0, inf.0]"
],
}
gamertag
score
db.games.createIndex({gamertag:1, score:1})

40. db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
R
E R
E
Equality before Range

41. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

42. Sort fields are placed next
Placing sort predicates after sequential equality keys allow for the index to:
Provide a non-blocking sort.
Minimize the amount of scanning required.
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort

43. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Acegamertag
score
db.games.createIndex({score:1, gamertag:1})

44. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{} {} {} {}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

45. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{} {} {} {}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

46. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
gamertag
score
db.games.createIndex({score:1, gamertag:1})

47. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
db.games.createIndex({score:1, gamertag:1})

48. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]"
]
}
db.games.createIndex({score:1, gamertag:1})

49. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

50. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

51. db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

52. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

53. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

54. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

55. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

56. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

57. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

58. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"score" : [
"[MinKey, MaxKey]"
],
"gamertag" : [
"["Ace", "Ace"]”
]
}
db.games.createIndex({score:1, gamertag:1})

59. Sort
100 15,000 50,000 99,999
Ace Bob Bob Ace
{1} {} {} {2}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )

60. Sort
Ace Bob Bob Ace
100 99,999 15,000 50,000
{1} {2} {} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )

61. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

62. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

63. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

64. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

65. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

66. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

67. Sort
100
Ace Bob
99,999 15,000 50,000
{}{1} {2} {}
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
gamertag
score
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
”score" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({gamertag:1, score:1})

68. Sort after Equality
S
E S
E
db.games.find( {gamertag: "Ace"} ).sort( {score: 1} )
Don’t do this, it may require a full index scan

69. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

70. Range fields are usually last
This allows them to :
Still participate in filtering the data
But does not force a blocking sort.
db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
Range

71. db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
R
E R
E
Range after Equality

72. db.games.find( {gamertag: "Ace", score: {$gt: 9000}} )
R
E R
E
Range after Equality
Should range come after sort
too?

73. R
E R
E
Range after Equality
Should range come after sort
too?
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})

74. R
E R
E
Range
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})

75. 100 15,000 50,000 99,999
Ace Bob Bob Ace
*
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
db.games.createIndex({ …, score:1, gamertag:1})

76. 100 15,000 50,000 99,999
Ace Bob Bob Ace
*
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
db.games.createIndex({ …, score:1, gamertag:1})

77. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
db.games.createIndex({ …, score:1, gamertag:1})

78. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {} {} {}{1}{2} {3}
gamertag
score
db.games.createIndex({ …, score:1, gamertag:1})

79. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

80. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

81. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

82. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

83. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

84. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

85. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

86. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

87. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

88. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
gamertag
score
"indexBounds" : {
*,
"score" : [
"(9000.0, inf.0]"
],
"gamertag" : [
"[MinKey, MaxKey]"
]
}
db.games.createIndex({ …, score:1, gamertag:1})

89. {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
Blocking SortBlocking Sort
BS

90. {2}{3}{1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
BS

91. 100 15,000 50,000 99,999
Ace Bob Cali Ace
*
{} {2} {3} {1}
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range

92. db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
*
Ace Bob Cali Ace
100 15,000 50,00099,999
{} {1} {2} {3}

93. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

94. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

95. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

96. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

97. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

98. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

99. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

100. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

101. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

102. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

103. *
100 15,000 50,00099,999
Ace Bob Cali
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range
{} {1} {3}
score
gamertag
"indexBounds" : {
*,
"gamertag" : [
"[MinKey, MaxKey]"
]
"score" : [
"(9000.0, inf.0]"
]
}
db.games.createIndex({ …, gamertag:1, score:1})
{2}

104. BS
R S
R
S
db.games.find({*, score: {$gt: 9000}}).sort({gamertag: 1})
Range after Sort

105. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

106. Operator Type Check
Some operators are simple
$eq: Equality
$gte: Range
Others are trickier

107. Operator Type Check - Inequality
Inequality Operators: E, S, or R?
• $ne:123
• $nin:[1,2]
Range!

108. Operator Type Check - Inequality
Inequality Operators: E, S, or R?
• $ne:123
• $nin:[1,2]
Range!
How do you know?

109. Operator Type Check - Inequality
Inequality Operators: E, S, or R?
• $ne:123
• $nin:[1,2]
Range!
"indexBounds" : {
"x" : [
"[MinKey, 123.0)",
"(123.0, MaxKey]"
]
}

110. Operator Type Check - Inequality
Range!
"indexBounds" : {
"x" : [
"[MinKey, 123.0)",
"(123.0, MaxKey]"
]
}
50 123 999

111. Operator Type Check - Inequality
Range!
"indexBounds" : {
"x" : [
"[MinKey, 123.0)",
"(123.0, MaxKey]"
]
}
50 123 999

112. Operator Type Check - Inequality
Range!
"indexBounds" : {
"x" : [
"[MinKey, 123.0)",
"(123.0, MaxKey]"
]
}
50 123 999

113. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!

114. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!

115. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
planecar racecar

116. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
planecar racecar

117. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
planecar racecar

118. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
p???ecar racecar

119. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
p???ecar racecar

120. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!

121. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry

122. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry

123. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry Carpool

124. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry Carpool

125. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry Carpool

126. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry Carpool
Since the regex is left
anchored, can’t we skip
the middle tree?

127. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
raincarry Carpool
Since the regex is left
anchored, can’t we skip
the middle tree?

128. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
cArrycarry Carpool
Since the regex is left
anchored, can’t we skip
the middle tree?

129. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
cArrycarry Carpool
Since the regex is left
anchored, can’t we skip
the middle tree?

130. Operator Type Check - Regex
Regex Operators: E, S, or R?
• {str:/car/}
• {str:/^car/i}
Range!
cArrycarry Carpool

131. Operator Type Check - $in
$in filters: E, S, or R?
• {field:{$in:[1,3]}}
… it depends with respect to key ordering
Alone: a series of Equality matches
Combined: possibly a Range

132. Operator Type Check - $in
.find({field:{$in:[1,3]}})

133. Operator Type Check - $in
.find({field:{$in:[1,3]}})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

134. Operator Type Check - $in
.find({field:{$in:[1,3]}})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

135. Operator Type Check - $in
.find({field:{$in:[1,3]}})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

136. Operator Type Check - $in
.find({field:{$in:[1,3]}})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

137. Operator Type Check - $in
.find({field:{$in:[1,3]}})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

138. Operator Type Check - $in
.find({field:{$in:[1,3]}})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

139. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

140. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

141. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

142. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

143. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

144. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
BS
db.coll.createIndex({field:1, sortField:1})

145. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
"[3.0, 3.0]"
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
BS
db.coll.createIndex({field:1, sortField:1})

146. Operator Type Check - $in
.find({field:{$in:[1,3]}})
.sort({sortField:1})
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

147. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1}) ?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

148. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

149. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

150. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

151. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

152. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

153. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
"indexBounds" : {
"field" : [
"[3.0, 3.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

154. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
"indexBounds" : {
"field" : [
"[3.0, 3.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

155. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
"indexBounds" : {
"field" : [
"[3.0, 3.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

156. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
"indexBounds" : {
"field" : [
"[3.0, 3.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
?
1 2 3
C G B F A D
db.coll.createIndex({field:1, sortField:1})

157. Operator Type Check - $in
.find({field:{$in:[1,3]}}).sort({sortField:1})
"indexBounds" : {
"field" : [
"[1.0, 1.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
"indexBounds" : {
"field" : [
"[3.0, 3.0]",
],
"sortField" : [
"[MinKey, MaxKey]"
]
}
?
1 2 3
C G B F A D
?
1 2 3
C G B F A D
{2} {4} {1} {3}
Sort Merge
db.coll.createIndex({field:1, sortField:1})

158. BS
S M
Operator Type Check - $in

159. Operator Type Check – Cheat Sheet
$eq - EQUALITY
$gte - RANGE
$ne - RANGE
$nin - RANGE
$regex – RANGE
$in
• If alone – a series of EQUALITY matches
• If combined – possibly a RANGE

160. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

161. Consecutive Index Keys
Given Indexes:
{gamertag:1, date:1, game:1}
{gamertag:1, game:1, date:1}
Which one is “better”?
It depends on the query shape(s)!
Consider the query:
.find({
gamertag:"Ace",
game: "Halo”
})

162. Consecutive Index Keys
.find({
gamertag:"Ace",
game: "Halo”
})

163. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
db.games.createIndex({gamertag:1, date:1, game:1})

164. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

165. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

166. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

167. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

168. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

169. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

170. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {} {} {}
db.games.createIndex({gamertag:1, date:1, game:1})

171. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
{} {}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {}
db.games.createIndex({gamertag:1, date:1, game:1})

172. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
{} {}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {}
db.games.createIndex({gamertag:1, date:1, game:1})

173. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
{} {}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {}
db.games.createIndex({gamertag:1, date:1, game:1})

174. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
{} {}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {}
db.games.createIndex({gamertag:1, date:1, game:1})

175. Consecutive Index Keys
Ace
Mario Halo
2016 2017
Mario Halo
2018 2019
.find({
gamertag:"Ace",
game: "Halo”
})
{} {}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{} {}
db.games.createIndex({gamertag:1, date:1, game:1})

176. Consecutive Index Keys
.find({
gamertag:"Ace",
game: "Halo”
})
{} {} {} {}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[MinKey, MaxKey]"
],
"game" : [
"["Halo", "Halo"]"
]
}
Halo
Ace
Mario Halo
2016 2017
Mario
2018 2019
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"game" : [
"["Halo", "Halo"]"
]
}
db.games.createIndex({gamertag:1, game:1})

177. Ace
2016 2017Mario2018 2019Halo
Consecutive Index Keys
.find({
gamertag:"Ace",
game: "Halo”
})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"game" : [
"["Halo", "Halo"]"
]
}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"game" : [
"["Halo", "Halo"]"
],
"date" : [
"[MinKey, MaxKey]"
]
}
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"game" : [
"["Halo", "Halo"]"
]
}
{}{} {}{}
db.games.createIndex({gamertag:1, game:1, date:1})

178. R
E
E E
E
E
E
Consecutive Index Keys
R
Look familiar? This is equality after range!

179. Roadmap
E-S-R Overview
Guidelines:
• Eà R
• Eà S
• Sà R
E-S-R Considerations
Operator Type Checks
Consecutive Index Keys
Exceptions?

180. Exceptions
Is the E-S-R “rule” always optimal?
Nope.
Consider the following query:
db.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})

181. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {} {1} {2}
db.games.createIndex({gamertag:1, score:1, date:1})

182. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

183. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

184. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

185. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

186. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

187. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

188. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

189. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

190. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

191. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

192. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

193. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

194. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

195. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
db.games.createIndex({gamertag:1, score:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"score" : [
"[MinKey, MaxKey]"
],
"date" : [
"[2019.0, inf.0]"
]
}
{1} {2}

196. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019
gamertag
score
date
{} {} {}
"executionStats" : {
"nReturned" : 2,
"executionTimeMillis" : 23,
"totalKeysExamined" : 9001,
"totalDocsExamined" : 2,
db.games.createIndex({gamertag:1, score:1, date:1})
{1} {2}

197. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
1 5,000 9,0012 9,000
… …
2001 2000 2015 2019 2019

198. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
2001 2000 2015 2019 2019
{score:2} {score:1} {score:5000} {score:9001} {score:9000}
… …
gamertag
date

199. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
… …
2000 2001 2015 2019 2019
{score:2} {score:1} {score:5000} {score:9001} {score:9000}
gamertag
date
db.games.createIndex({gamertag:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[2019.0, inf.0]"
]
}

200. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
… …
2000 2001 2015 2019 2019
{score:2} {score:1} {score:5000} {score:9001} {score:9000}
gamertag
date
db.games.createIndex({gamertag:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[2019.0, inf.0]"
]
}

201. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
… …
2000 2001 2015 2019 2019
{score:2} {score:1} {score:5000} {score:9001} {score:9000}
gamertag
date
db.games.createIndex({gamertag:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[2019.0, inf.0]"
]
}

202. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
… …
2000 2001 2015 2019 2019
{score:2} {score:1} {score:5000} {score:9001} {score:9000}
gamertag
date
db.games.createIndex({gamertag:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[2019.0, inf.0]"
]
}

203. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
… …
2000 2001 2015 2019 2019
{score:2} {score:1} {score:5000} {score:9001} {score:9000}
gamertag
date
db.games.createIndex({gamertag:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[2019.0, inf.0]"
]
}

204. Exceptionsdb.games
.find({gamertag:"Ace", date:{$gte:2019}})
.sort({score:1})
Ace
… …
2000 2001 2015 2019 2019
{score:2} {score:1} {score:5000}
gamertag
date
{score:9001} {score:9000}
BS
"executionStats" : {
"nReturned" : 2,
"executionTimeMillis" : 0,
"totalKeysExamined" : 2,
"totalDocsExamined" : 2,
"executionStats" : {
"nReturned" : 2,
"executionTimeMillis" : 0,
"totalKeysExamined" : 2,
"totalDocsExamined" : 2,
"executionStages" : {
"stage" : "SORT",
"memUsage" : 154,
"memLimit" : 33554432,
db.games.createIndex({gamertag:1, date:1})
"indexBounds" : {
"gamertag" : [
"["Ace", "Ace"]"
],
"date" : [
"[2019.0, inf.0]"
]
}

205. Exceptions
……… …
BS
S
R
E
R
E

206. Summary

207. E-S-R Guidance
A good starting place applicable to
most use cases
Place keys in the following order:
Equality first
Sort next
Range last
Remember:
• Some operators may be range
instead of equality
• Having consecutive keys used in
the index is important
• Specifics about your data set may
need a different approach

208. Thank You!