This document provides an overview of a Neo4j basic training session. The training will cover querying graph patterns with Cypher, designing and implementing a graph database model, and evolving existing graphs to support new requirements. Attendees will learn about graph modeling concepts like nodes, relationships, properties and labels. They will go through a modeling workflow example of developing a graph model to represent airport connectivity data from a CSV file and querying the resulting graph.

1. Neo4j Basic Training

2. Welcome everyone
Please say hi to each other.
We'll spend the rest of the day together.

3. What are we going to learn today?
• Querying graph pa;erns with Cypher,
• Designing and implemen@ng a graph database model
• Evolving an exis@ng graph to support new or changed requirements.

4. • Intro to graphs and graph modeling
• Evolving the graph model
• Missing domain concept
• Rela@onship bundling
• Modeling guidelines
What are we going to do today?

5. Op:onal Modules
• Further evolving the graph model
• Specific rela@onship types
• Refactoring large graphs
• Mul@ple models
• Your turn

6. Thank you for your @me
Any other ques@ons?
Feedback form: bit.ly/neo-survey gives a discount

7. Intro to graph modeling

8. • Intro to the property graph model
• The airport dataset
• The modeling workflow
• Load CSV data
What are we going to do?

9. The labelled property graph
• Nodes
• Rela@onships
• Proper@es
• Labels
CAR
name: “Dan”
born: May 29, 1970
twi;er: “@dan”
name: “Ann”
born: Dec 5, 1975
since:
Jan 10, 2011
brand: “Volvo”
model: “V70”
PERSON PERSON
LOVES
LOVES
LIVES WITH

10. CAR
Property Graph Model Components
Nodes
• Represent the objects in the graph
• Can be labeled
PERSON PERSON

11. CAR
Property Graph Model Components
Nodes
• Represent the objects in the
graph
• Can be labeled
Rela:onships
• Relate nodes by type and direc-on
LOVES
LOVES
LIVES WITH
PERSON PERSON

12. CAR
name: “Dan”
born: May 29, 1970
twi;er: “@dan”
name: “Ann”
born: Dec 5, 1975
since:
Jan 10, 2011
brand: “Volvo”
model: “V70”
Property Graph Model Components
Nodes
• Represent the objects in the
graph
• Can be labeled
Rela:onships
• Relate nodes by type and
direc-on
Proper:es
• Name-value pairs that can go on
nodes and rela@onships.
LOVES
LOVES
LIVES WITH
PERSON PERSON

13. The modeling workflow
1. Derive the
question
2. Obtain the
data
3. Develop a
model
4. Ingest the
data
5. Query/Prove
our model

14. The modeling workflow
1. Derive the
question
2. Obtain the
data
3. Develop a
model
4. Ingest the
data
5. Query/Prove
our model

15. The Modeling Workflow

16. Models

17. Find the most popular airports
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

18. The flights dataset

19. What data do we have?

20. Derive ques:ons
Is Airport A connected to Airport B?
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

21. Iden:ty en::es
Is Airport A connected to Airport B?
airport

22. Iden:fy rela:onships between en::es
Is Airport A connected to Airport B?
airport CONNECTED_TO airport

23. It’s a graph!
Is Airport A connected to Airport B?
(airport)-[:CONNECTED_TO]->(airport)

24. It’s a graph!
Is Airport A connected to Airport B?
(airport)-[:CONNECTED_TO]->(airport)

25. Labels
Labels are for categorizing nodes.

26. Proper:es
Proper@es are for defining a;ributes of nodes or rela@onships.
We need an airport code to uniquely iden@fy each airport.

27. Modeling different connec:ons
Busy airports will have mul@ple connec@ons between them. We can
model this in different ways:
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

28. Sample data

29. Copy folders
• import
• plugins
from USB S:ck
to the default.graphdb folder
(or $NEO4J_HOME)
bit.ly/neo4j-modeling-data
Prepare your Neo4j graph.db directory

30. 1. Start the server.
2. It should be running on: http://localhost:7474
3. Log-in with default creden@als
user: neo4j password: neo4j
4. Choose a new password
We’re good to go!
Make sure you’ve got Neo4j running

31. Find the most popular airports
Open your browser to http://localhost:7474 and execute the following
command:
:play https://guides.neo4j.com/modeling_airports

32. Play the guides in your browser un:l you see...

33. The MERGE command

34. MERGE
The MERGE command is a combina@on of MATCH and CREATE. If the pa;ern
already exists then it will return it; if not it will create it.
en.wikipedia.org/wiki/Idempotence

35. MERGE (las:Airport {code: "LAS"})
RETURN las
We can MERGE nodes...

36. ...or rela:onships...
MATCH (las:Airport {code: "LAS"})
MATCH (lax:Airport {code: "LAX"})
MERGE (las)-[:CONNECTED_TO]->(lax)

37. ...or both
MERGE (las:Airport {code: "LAS"})
MERGE (lax:Airport {code: "LAX"})
MERGE (las)-[:CONNECTED_TO]->(lax)
MERGE (las:Airport {code: "LAS"})-[:CONNECTED_TO]->(lax:Airport
{code: "LAX"})

38. Con:nue playing the guide
Con@nue the guide in your browser

39. The modeling workflow

40. As an air travel enthusiast
I want to know how airports are connected So that I can find the busiest ones
The modeling workflow
MATCH (origin:Airport {code: "LAX"})
-[flight:CONNECTED_TO]->
(destination:Airport {code: "LAS"})
RETURN origin, destination, flight
LIMIT 10
CREATE (lax:Airport {code: "LAX"})
CREATE (las:Airport {code: "LAS"})
CREATE (las)-[connection:CONNECTED_TO {
airline: "WN",
flightNumber: "82",
date: "2008-1-3",
departure: 1715,
arrival: 1820}]->(lax)
|---------+------+------------|
| Origin | Dest | FlightNum |
|---------+------+------------|
| IAD | TPA | 335 |
| IAD | TPA | 3231 |
| IND | BWI | 448 |
| IND | BWI | 3920 |
|---------+------+------------|
Is Airport A connected to Airport B?
(airport)-[:CONNECTED_TO]->(airport)

41. Modeling airports
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

42. Nodes
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

43. Labels
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

44. Rela:onships
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

45. Proper:es
As an air travel enthusiast I want to know how airports are connected
So that I can find the busiest ones

46. Loading CSV data

47. Load CSV
A clause in the Cypher query language that lets us iterate over CSV files
and create graph structures based on the data contained in each row.

48. Load CSV
LOAD CSV // load csv data
WITH HEADERS // optionally use first header row as keys in "row" map
FROM "url" // file:// URL relative to $NEO4J_HOME/import or http://
AS row // return each row of the CSV as list of strings or map
// ... rest of the Cypher statement ...

49. Load CSV
[USING PERIODIC COMMIT] // optionally batch transactions
LOAD CSV // load csv data
WITH HEADERS // optionally use first header row as keys in "row" map
FROM "url" // file:// URL relative to $NEO4J_HOME/import or http://
AS row // return each row of the CSV as list of strings or map
[FIELDTERMINATOR ";"] // optionally alt. delimiter
// ... rest of the Cypher statement ...

50. Consider this CSV file
|---------+------+------------|
| Origin | Dest | FlightNum |
|---------+------+------------|
| IAD | TPA | 335 |
| IAD | TPA | 3231 |
| IND | BWI | 448 |
| IND | BWI | 3920 |
|---------+------+------------|

51. Create nodes
LOAD CSV WITH HEADERS FROM "file:///flights.csv" AS row
CREATE (:Airport {code: row.Origin})
CREATE (:Airport {code: row.Dest})
|---------+------+------------|
| Origin | Dest | FlightNum |
|---------+------+------------|
| IAD | TPA | 335 |
| IAD | TPA | 3231 |
| IND | BWI | 448 |
| IND | BWI | 3920 |
|---------+------+------------|

52. Create rela:onships
LOAD CSV WITH HEADERS FROM "file:///flights.csv" AS row
CREATE (origin:Airport {code: row.Origin})
CREATE (destination:Airport {code: row.Dest})
CREATE (origin)-[:CONNECTED_TO {flightNumber: row.FlightNum}]->(destination)
|---------+------+------------|
| Origin | Dest | FlightNum |
|---------+------+------------|
| IAD | TPA | 335 |
| IAD | TPA | 3231 |
| IND | BWI | 448 |
| IND | BWI | 3920 |
|---------+------+------------|

53. Find exis:ng nodes and rela:onships
LOAD CSV WITH HEADERS FROM "file:///flights.csv" AS row
MATCH (origin:Airport {code: row.Origin})
MATCH (destination:Airport {code: row.Dest})
MATCH (origin)-[:CONNECTED_TO {flightNumber: row.FlightNum}]->(destination)
...
|---------+------+------------|
| Origin | Dest | FlightNum |
|---------+------+------------|
| IAD | TPA | 335 |
| IAD | TPA | 3231 |
| IND | BWI | 448 |
| IND | BWI | 3920 |
|---------+------+------------|

54. Update exis:ng nodes and rela:onships
|---------+------+-----------+----------------|
| Origin | Dest | FlightNum | UniqueCarrier |
|---------+------+-----------+----------------|
| IAD | TPA | 335 | WN |
| IAD | TPA | 3231 | WN |
| IND | BWI | 448 | WN |
| IND | BWI | 3920 | WN |
|---------+------+-----------+----------------|
LOAD CSV WITH HEADERS FROM "file:///flights.csv" AS row
MATCH (origin:Airport {code: row.Origin})
MATCH (destination:Airport {code: row.Dest})
MATCH (origin)-[c:CONNECTED_TO {flightNumber:row.FlightNum}]->(destination)
SET c.airline = row.UniqueCarrier

55. Idempotently create nodes and rela:onships
LOAD CSV WITH HEADERS FROM "file:///flights.csv" AS row
MERGE (origin:Airport {code: row.Origin})
MERGE (destination:Airport {code: row.Dest})
MERGE (origin)-[:CONNECTED_TO {flightNumber: row.FlightNum}]-
>(destination)
|---------+------+------------|
| Origin | Dest | FlightNum |
|---------+------+------------|
| IAD | TPA | 335 |
| IAD | TPA | 3231 |
| IND | BWI | 448 |
| IND | BWI | 3920 |
|---------+------+------------|

56. Let’s give it a try
Con@nue the guide in your browser

57. End of Module
Intro to Graph Modeling
Ques:ons ?

58. Missing domain concept

59. What are we going to do?
• Profile queries
• Introduce a missing concept in the domain
• Constraints and indexes
• Write our first refactoring query

60. Start playing the next guide….
...if you aren’t playing it already
:play http://guides.neo4j.com/modeling_airports/02_flight.html

61. Profiling queries

62. How do I profile a query?
By prefixing the query with:
EXPLAIN
shows the execu@on plan without actually execu@ng it or returning any results.

63. How do I profile a query?
By prefixing the query with:
EXPLAIN
shows the execu@on plan without actually execu@ng it or returning any results.
PROFILE
executes the statement and returns the results along with profiling informa@on.

64. How do I profile a query?
EXPLAIN
MATCH (origin:Airport)-[c:CONNECTED_TO]
->(destination:Airport)
WHERE destination.code = "LAS"
RETURN origin, destination, c
LIMIT 10

65. How do I profile a query?
PROFILE
MATCH (origin:Airport)-[c:CONNECTED_TO]
->(destination:Airport)
WHERE destination.code = "LAS"
RETURN origin, destination, c
LIMIT 10

66. PROFILE
MATCH (origin:Airport)-[c:CONNECTED_TO]
->(destination:Airport)
WHERE destination.code = "LAS"
RETURN origin, destination, c
LIMIT 10
Anatomy of an execu:on plan

67. Opera:ons
Rows come in
Do some work
Rows go out

68. What’s our goal?
At a high level, the goal is
simple: get the number of db
hits down.

69. What is a database hit?
an abstract unit of storage
engine work.
“
”

70. Let’s profile some queries
Con@nue playing the guide in your browser

71. Introducing a missing
domain concept

72. Introducing a missing domain concept
Some@mes we design a model and amer working with it for a bit we
realise that we’ve missed an important domain concept.

73. Introducing a missing domain concept
Some@mes we design a model and amer working with it for a bit we
realise that we’ve missed an important domain concept.
In our case we’re missing nodes to represent Flights

74. Introducing a missing domain concept

75. Flight as a first class ci:zen
???

76. Flight as a first class ci:zen
MATCH (o:Airport)-[:CONNECTED_TO]->(d:Airport)
MERGE...

77. Constraints and indexes

78. Unique Constraints
We create unique constraints to:
• ensure uniqueness
• allow fast lookup of nodes which match label-property pairs.

79. Unique Constraints
We create unique constraints to:
• ensure uniqueness
• allow fast lookup of nodes which match label-property pairs.
CREATE CONSTRAINT ON (identifier:Label)
ASSERT identifier.property IS UNIQUE

80. This is the first of the refactoring pa;erns that we’ll encounter today.
We have this pa;ern:
(origin)-[:CONNECTED_TO]->(destination)
And we’ll create a new node using the proper@es of the CONNECTED_TO
rela@onship:
(origin)<-[:ORIGIN]-(flight)-[:DESTINATION]->(destination)
Refactoring: Derive node from rela:onship

81. Indexes
We create indexes to:
• allow fast lookup of nodes which match label-property pairs.

82. Indexes
We create indexes to:
• allow fast lookup of nodes which match label-property pairs.
CREATE INDEX ON :Label(property)

83. What gets indexed?
The following are index backed:
• Equality
• STARTS WITH
• CONTAINS
• ENDS WITH
• Range searches
• (Non-) existence checks

84. How are indexes used in neo4j?
Indexes are only used to find the star@ng point for queries.
Use index scans to look up rows in
tables and join them with rows
from other tables
Use indexes to find the star@ng
points for a query.
Relational
Graph

85. Let’s get on with the refactoring
Con@nue playing the guide in your browser

86. End of Module
Missing Concept
Ques:ons?

87. Rela:onship Bundling

88. Rela:onship Bundling
So far we’ve been wri@ng queries from the perspec@ve of an air travel
enthusiast.
In this sec@on we’re going to evolve the model based on the needs of a
frequent traveller who wants to find flights on a specific date.

89. What are we going to do?
• Write a query to book a flight on a specific day
• Profile our flight booking query
• Op@mise our model to deal with this query

90. Find a flight to book
As a frequent traveller I want to find flights from <origin> to
<des@na@on> on <date> So that I can book my business flight

91. Start playing the next guide….
...if you aren’t playing it already
:play http://guides.neo4j.com/modeling_airports/03_flight_booking.html

92. Bundling flight rela:onships

93. Bundling flight rela:onships by airport day
Searching for flights by day is a bit problema@c. We have to scan every
rela@onship between origin and des@na@on airports and analyse
proper@es on each flight to work out which ones we’re interested in.

94. Bundling flight rela:onships by airport day
Searching for flights by day is a bit problema@c. We have to scan every
rela@onship between origin and des@na@on airports and analyse
proper@es on each flight to work out which ones we’re interested in.
We can reduce this problem by bundling flights together by
AirportDay

95. Our current model

96. Introducing AirportDay

97. Refactoring to Airport Day
???

98. Bundling flight rela:onships by airport day

99. Refactoring: Derive node from property
This refactoring creates a new node using the property of an exis@ng node.
We currently have this pa;ern:
(origin)<-[:ORIGIN]-(flight)-[:DESTINATION]->(destination)
And we’ll create a new node using the date property of the flight node:
(origin)-[:HAS_DAY]->(originAirportDay)<-[:ORIGIN]-(flight),
(destination)-[:HAS_DAY]->(destAirportDay)<-[:DESTINATION]-(flight)

100. Let’s get on with the refactoring
Over to you!

101. End of Module
Bundling Rela:onships
Ques:ons?

102. Modeling Guidelines

103. • Recap of the Property Graph Model
• Modeling choices
• Refactorings
What are we going to do?

104. Nodes, rela:onships,
labels, proper:es

105. Our model

106. Nodes are for things

107. Labels for grouping

108. Rela:onships for structure

109. Proper:es for a]ributes

110. Modeling choices

111. Properties vs.
Relationships

112. Proper:es vs Rela:onships

113. We only need to pull out a node if we’re going to query through it,
otherwise a property will suffice.
But if we pull out every single property then we end up with an RDF
model and lose the benefit of the property graph
Proper:es vs Rela:onships

114. Relationship
Granularity

115. Rela:onship Granularity

116. Symmetric
Relationships

117. Symmetric rela:onships
OR

118. Bidirectional
Relationships

119. Bidirec:onal rela:onships

120. No need to have the rela:onship in both direc:ons

121. Use single rela:onship and ignore direc:on in queries
MATCH (:Person {name:'Eric'})-[:MARRIED_TO]-(p2)
RETURN p2

122. General vs. Specific
Relationships

123. General Rela:onships

124. General: Find flights on a specific date
MATCH (origin:Airport {code: "LAS"})-[:HAS_DAY]->(originDay:AirportDay),
(originDay)<-[:ORIGIN]-(flight:Flight),
(flight)-[:DESTINATION]->(destinationDay),
(destinationDay:AirportDay)<-[:HAS_DAY]-(destination:Airport {code: "MDW"})
WHERE originDay.date = "2008-1-3" AND destinationDay.date = "2008-1-3"
RETURN flight.date, flight.number, flight.airline, flight.departure, flight.arrival
ORDER BY flight.date, flight.departure

125. Specific Rela:onships

126. Specific: Find flights on a specific date
MATCH (origin:Airport {code: "LAS"})-[:`2008-1-3`]->(originDay:AirportDay),
(originDay)<-[:ORIGIN]-(flight:Flight),
(flight)-[:DESTINATION]->(destinationDay),
(destinationDay:AirportDay)<-[:`2008-1-3`]-(destination:Airport {code: "MDW"})
RETURN flight.date, flight.number, flight.airline, flight.departure, flight.arrival
ORDER BY flight.date, flight.departure;

127. General: Find flights by year and month
MATCH (origin:Airport {code: "LAS"})-[:HAS_DAY]->(originDay:AirportDay),
(originDay)<-[:ORIGIN]-(flight:Flight)
WHERE originDay.date STARTS WITH "2008-1"
RETURN flight.date, flight.number, flight.airline, flight.departure, flight.arrival
ORDER BY flight.date, flight.departure

128. Specific: Find flights by year and month
MATCH (origin:Airport {code: "LAS"})
-[:`2008-1-3`|:`2008-1-4`|:`2008-1-5`|:`2008-1-6`]->(originDay:AirportDay),
(originDay)<-[:ORIGIN]-(flight:Flight)
RETURN flight.date, flight.number, flight.airline, flight.departure, flight.arrival
ORDER BY flight.date, flight.departure

129. Best of both worlds?

130. Refactorings

131. Derive node from rela:onship
(origin)-[:CONNECTED_TO]->(destination)
(origin)<-[:ORIGIN]-(flight)-[:DESTINATION]->(destination)

132. Derive node from property
(origin)<-[:ORIGIN]-(flight)-[:DESTINATION]->(destination)
(origin)-[:HAS_DAY]->(originAirportDay)<-[:ORIGIN]-(flight),
(destination)-[:HAS_DAY]->(destAirportDay)<-[:DESTINATION]-(flight)

133. Derive rela:onship from property
(airport)-[:HAS_DAY]->(airportDay {date: "2008-1-3"})
(airport)-[:`2008-1-3`]->(airportDay {date: "2008-1-3"})

134. Evolving the Model

135. Revealing nodes

136. Revealing nodes?
?

137. End of Module
Modeling Guidelines
Ques:ons ?