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Redis Graph Commands

GRAPH.QUERY

Executes the given query against a specified graph.

Arguments: Graph name, Query

Returns: Result set

GRAPH.QUERY us_government "MATCH (p:president)-[:born]->(:state {name:'Hawaii'}) RETURN p"

Query language

The syntax is based on Cypher, and only a subset of the language currently supported.

  1. Clauses
  2. Functions

Query structure

  • MATCH
  • WHERE
  • RETURN
  • ORDER BY
  • LIMIT
  • CREATE
  • MERGE
  • DELETE
  • SET

MATCH

Match describes the relationship between queried entities, using ascii art to represent pattern(s) to match against.

Nodes are represented by parenthesis (), and Relationships are represented by brackets [].

Each graph entity node/relationship can contain an alias and a label/relationship type, but both can be left empty if necessary.

Entity structure: alias:label {filters}.

Alias, label/relationship type and filters are all optional.

Example:

(a:actor)-[:act]->(m:movie {title:"straight outta compton"})

a is an alias for the source node, which we'll be able to refer to at different places within our query.

actor is the label under which this node is marked.

act is the relationship type.

m is an alias for the destination node.

movie destination node is of "type" movie.

{title:"straight outta compton"} requires the node's title attribute to equal "straight outta compton".

In this example, we're interested in actor entities which have the relation "act" with the entity representing the "straight outta compton" movie.

It is possible to describe broader relationships by composing a multi-hop query such as:

(me {name:'swilly'})-[:friends_with]->()-[:friends_with]->(foaf)

Here we're interested in finding out who my friends' friends are.

Nodes can have more than one relationship coming in or out of them, for instance:

(me {name:'swilly'})-[:visited]->(c:country)<-[:visited]-(friend)<-[:friends_with]-({name:'swilly'})

Here we're interested in knowing which of my friends have visited at least one country I've been to.

Variable length relationships

Nodes that are a variable number of relationship→node hops away can be found using the following syntax:

-[:type*minHops..maxHops]

type, minHops and maxHops are all optional and default to type agnostic, 1 and infinity, respectively.

When no bounds are given the dots may be omitted. The dots may also be omitted when setting only one bound and this implies a fixed length pattern.

Example:

MATCH (martin:actor { name: 'Charlie Sheen' })-[:PLAYED_WITH*1..3]-(colleague:actor)
RETURN colleague

Returns all actors related to 'Charlie Sheen' by 1 to 3 hops.

WHERE

This clause is not mandatory, but if you want to filter results, you can specify your predicates here.

Supported operations:

  • =
  • !=
  • <
  • <=
  • >
  • >=

Predicates can be combined using AND / OR.

Be sure to wrap predicates within parentheses to control precedence.

Examples:

WHERE (actor.name = "john doe" OR movie.rating > 8.8) AND movie.votes <= 250)
WHERE actor.age >= director.age AND actor.age > 32

It is also possible to specify equality predicates within nodes using the curly braces as such:

(:president {name:"Jed Bartlett"})-[:won]->(:state)

Here we've required that the president node's name will have the value "Jed Bartlett".

There's no difference between inline predicates and predicates specified within the WHERE clause.

RETURN

In its simple form, Return defines which properties the returned result-set will contain.

Its structure is a list of alias.property separated by commas.

For convenience, it's possible to specify the alias only when you're interested in every attribute an entity possesses, and don't want to specify each attribute individually. For example:

RETURN movie.title, actor

Use the DISTINCT keyword to remove duplications within the result-set:

RETURN DISTINCT friend_of_friend.name

In the above example, suppose we have two friends, Joe and Miesha, and both know Dominick.

DISTINCT will make sure Dominick will only appear once in the final result set.

Return can also be used to aggregate data, similar to group by in SQL.

Once an aggregation function is added to the return list, all other "none" aggregated values are considered as group keys, for example:

RETURN movie.title, MAX(actor.age), MIN(actor.age)

Here we group data by movie title and for each movie, and we find its youngest and oldest actor age.

Aggregations

Supported aggregation functions include:

  • sum
  • avg
  • min
  • max
  • count
  • percentileCont
  • percentileDisc
  • stDev

ORDER BY

Order by specifies that the output be sorted and how.

You can order by multiple properties by stating each variable in the ORDER BY clause.

The result will be sorted by the first variable listed.

For equal values, it will go to the next property in the ORDER BY clause, and so on.

ORDER BY <alias.property list> [ASC/DESC]

Below we sort our friends by height. For equal heights, weight is used to break ties.

ORDER BY friend.height, friend.weight DESC

LIMIT

Although not mandatory, you can use the limit clause to limit the number of records returned by a query:

LIMIT <max records to return>

If not specified, there's no limit to the number of records returned by a query.

CREATE

CREATE is used to introduce new nodes and relationships.

The simplest example of CREATE would be a single node creation:

CREATE (n)

It's possible to create multiple entities by separating them with a comma.

CREATE (n),(m)
CREATE (:person {name: 'Kurt', age:27})

To add relations between nodes, in the following example we first find an existing source node. After it's found, we create a new relationship and destination node.

MATCH(a:person)
WHERE a.name = 'Kurt'
CREATE (a)-[:member]->(:band {name:"Nirvana"})

Here the source node is a bounded node, while the destination node is unbounded.

As a result, a new node is created representing the band Nirvana and a new relation connects Kurt to the band.

Lastly we create a complete pattern.

All entities within the pattern which are not bounded will be created.

CREATE (jim:person{name:'Jim', age:29})-[:friends]->(pam:person {name:'Pam', age:27})-[:works]->(:employer {name:'Dunder Mifflin'})

This query will create three nodes and two relationships.

DELETE

DELETE is used to remove both nodes and relationships.

Note that deleting a node also deletes all of its incoming and outgoing relationships.

To delete a node and all of its relationships:

MATCH (p:person {name:'Jim'})
DELETE p

To delete relationship:

MATCH (p:person {name:'Jim'})-[r:friends]->()
DELETE r

This query will delete all friend outgoing relationships from the node with the name 'Jim'.

SET

SET is used to create or update properties on nodes and relationships.

To set a property on a node, use SET.

MATCH (n { name: 'Jim' }) SET n.name = 'Bob'

If you want to set multiple properties in one go, simply separate them with a comma to set multiple properties using a single SET clause.

MATCH (n { name: 'Jim', age:32 })
SET n.age = 33, n.name = 'Bob'

To remove a node's property, simply set property value to NULL.

MATCH (n { name: 'Jim' }) SET n.name = NULL

MERGE

The MERGE clause ensures that a pattern exists in the graph (either the pattern already exists, or it needs to be created).

Currently, MERGE only functions as a standalone clause so it cannot be combined with other directives such as MATCH or RETURN.

MERGE either matches existing nodes and binds them, or it creates new data and binds that.

It’s like a combination of MATCH and CREATE that also allows you to specify what happens if the data was matched or created.

For example, you can specify that the graph must contain a node for a user with a certain name.

If there isn’t a node with the correct name, a new node will be created and its name property set.

When using MERGE on full patterns, either the whole pattern matches or the whole pattern is created.

MERGE will not partially use existing patterns — it’s all or nothing.

To merge a single node with a label:

MERGE (robert:Critic)

To merge a single node with properties:

MERGE (charlie { name: 'Charlie Sheen', age: 10 })

To merge a single node, specifying both label and property:

MERGE (michael:Person { name: 'Michael Douglas' })

To merge on a relation:

MERGE (charlie { name: 'Charlie Sheen', age: 10 })-[r:ACTED_IN]->(wallStreet:MOVIE)

Functions

This section contains information on all supported functions from the Cypher query language.

Aggregating functions

Function Description
avg() Returns the average of a set of numeric values
count() Returns the number of values or rows
max() Returns the maximum value in a set of values
min() Returns the minimum value in a set of values
sum() Returns the sum of a set of numeric values
percentileDisc() Returns the percentile of the given value over a group, with a percentile from 0.0 to 1.0
percentileCont() Returns the percentile of the given value over a group, with a percentile from 0.0 to 1.0
stDev() Returns the standard deviation for the given value over a group

Mathematical functions

Function Description
abs() Returns the absolute value of a number
ceil() Returns the smallest floating point number that is greater than or equal to a number and equal to a mathematical integer
floor() Returns the largest floating point number that is less than or equal to a number and equal to a mathematical integer
rand() Returns a random floating point number in the range from 0 to 1; i.e. [0,1]
round() Returns the value of a number rounded to the nearest integer
sign() Returns the signum of a number: 0 if the number is 0, -1 for any negative number, and 1 for any positive number

String functions

Function Description
left() Returns a string containing the specified number of leftmost characters of the original string
lTrim() Returns the original string with leading whitespace removed
reverse() Returns a string in which the order of all characters in the original string are reversed
right() Returns a string containing the specified number of rightmost characters of the original string
rTrim() Returns the original string with trailing whitespace removed
substring() Returns a substring of the original string, beginning with a 0-based index start and length
toLower() Returns the original string in lowercase
toString() Converts an integer, float or boolean value to a string
toUpper() Returns the original string in uppercase
trim() Returns the original string with leading and trailing whitespace removed

Scalar functions

Function Description
id() Returns the ID of a relationship or node
labels() Returns a string representations of the label of a node.

GRAPH.DELETE

Completely removes the graph and all of its entities.

Arguments: Graph name

Returns: String indicating if operation succeeded or failed.

GRAPH.DELETE us_government

Note: To delete a node from the graph (not the entire graph), execute a MATCH query and pass the alias to the DELETE clause:

MATCH (x:y {propname: propvalue}) DELETE x

WARNING: When you delete a node, all of the node's incoming/outgoing relationships are also removed.

GRAPH.EXPLAIN

Constructs a query execution plan but does not run it. Inspect this execution plan to better understand how your query will get executed.

Arguments: Graph name, Query

Returns: String representation of a query execution plan

GRAPH.EXPLAIN us_government "MATCH (p:president)-[:born]->(h:state {name:'Hawaii'}) RETURN p"