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
• OPTIONAL MATCH
• WHERE
• RETURN
• ORDER BY
• SKIP
• LIMIT
• CREATE
• MERGE
• DELETE
• SET
• WITH
• UNION

MATCH ¶

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

Nodes are represented by parentheses () , 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]-(me)

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:

GRAPH.QUERY DEMO_GRAPH
"MATCH (charlie:Actor { name: 'Charlie Sheen' })-[:PLAYED_WITH*1..3]->(colleague:Actor)
RETURN colleague"

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

Bidirectional path traversal ¶

If a relationship pattern does not specify a direction, it will match regardless of which node is the source and which is the destination:

-[:TYPE]-

Example:

GRAPH.QUERY DEMO_GRAPH
"MATCH (person_a:Person)-[:KNOWS]-(person_b:Person)
RETURN person_a, person_b"

Returns all pairs of people connected by a KNOWS relationship. Note that each pair will be returned twice, once with each node in the person_a field and once in the person_b field.

The syntactic sugar (person_a)<-[:KNOWS]->(person_b) will return the same results.

The bracketed edge description can be omitted if all relations should be considered: (person_a)--(person_b) .

Named paths ¶

Named path variables are created by assigning a path in a MATCH clause to a single alias with the syntax: MATCH named_path = (path)-[to]->(capture)

The named path includes all entities in the path, regardless of whether they have been explicitly aliased. Named paths can be accessed using designated built-in functions or returned directly if using a language-specific client.

Example:

GRAPH.QUERY DEMO_GRAPH
"MATCH p=(charlie:Actor { name: 'Charlie Sheen' })-[:PLAYED_WITH*1..3]->(:Actor)
RETURN nodes(p) as actors"

This query will produce all the paths matching the pattern contained in the named path p . All of these paths will share the same starting point, the actor node representing Charlie Sheen, but will otherwise vary in length and contents. Though the variable-length traversal and (:Actor) endpoint are not explicitly aliased, all nodes and edges traversed along the path will be included in p . In this case, we are only interested in the nodes of each path, which we'll collect using the built-in function nodes() . The returned value will contain, in order, Charlie Sheen, between 0 and 2 intermediate nodes, and the unaliased endpoint.

OPTIONAL MATCH ¶

The OPTIONAL MATCH clause is a MATCH variant that produces null values for elements that do not match successfully, rather than the all-or-nothing logic for patterns in MATCH clauses.

It can be considered to fill the same role as LEFT/RIGHT JOIN does in SQL, as MATCH entities must be resolved but nodes and edges introduced in OPTIONAL MATCH will be returned as nulls if they cannot be found.

OPTIONAL MATCH clauses accept the same patterns as standard MATCH clauses, and may similarly be modified by WHERE clauses.

Multiple MATCH and OPTIONAL MATCH clauses can be chained together, though a mandatory MATCH cannot follow an optional one.

GRAPH.QUERY DEMO_GRAPH
"MATCH (p:Person) OPTIONAL MATCH (p)-[w:WORKS_AT]->(c:Company)
WHERE w.start_date > 2016
RETURN p, w, c"

All Person nodes are returned, as well as any WORKS_AT relations and Company nodes that can be resolved and satisfy the start_date constraint. For each Person that does not resolve the optional pattern, the person will be returned as normal and the non-matching elements will be returned as null.

Cypher is lenient in its handling of null values, so actions like property accesses and function calls on null values will return null values rather than emit errors.

GRAPH.QUERY DEMO_GRAPH
"MATCH (p:Person) OPTIONAL MATCH (p)-[w:WORKS_AT]->(c:Company)
RETURN p, w.department, ID(c) as ID"

In this case, w.department and ID will be returned if the OPTIONAL MATCH was successful, and will be null otherwise.

Clauses like SET, CREATE, MERGE, and DELETE will ignore null inputs and perform the expected updates on real inputs. One exception to this is that attempting to create a relation with a null endpoint will cause an error:

GRAPH.QUERY DEMO_GRAPH
"MATCH (p:Person) OPTIONAL MATCH (p)-[w:WORKS_AT]->(c:Company)
CREATE (c)-[:NEW_RELATION]->(:NEW_NODE)"

If c is null for any record, this query will emit an error. In this case, no changes to the graph are committed, even if some values for c were resolved.

WHERE ¶

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

Supported operations:

• =
• <>
• <
• <=
• >
• >=
• CONTAINS
• ENDS WITH
• IN
• STARTS WITH

Predicates can be combined using AND / OR / NOT.

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.

It is also possible to filter on graph patterns. The following queries, which return all presidents and the states they won in, produce the same results:

MATCH (p:President), (s:State) WHERE (p)-[:WON]->(s) RETURN p, s

and

MATCH (p:President)-[:WON]->(s:State) RETURN p, s

Pattern predicates can be also negated and combined with the logical operators AND, OR, and NOT. The following query returns all the presidents that did not win in the states where they were governors:

MATCH (p:President), (s:State) WHERE NOT (p)-[:WON]->(s) AND (p)->[:governor]->(s) RETURN p, s

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:

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

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.

Each property may specify its sort order with ASC / ASCENDING or DESC / DESCENDING . If no order is specified, it defaults to ascending.

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 [ASC/DESC] list>

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

ORDER BY friend.height, friend.weight DESC

SKIP ¶

The optional skip clause allows a specified number of records to be omitted from the result set.

SKIP <number of records to skip>

This can be useful when processing results in batches. A query that would examine the second 100-element batch of nodes with the label Person , for example, would be:

GRAPH.QUERY DEMO_GRAPH "MATCH (p:Person) RETURN p ORDER BY p.name SKIP 100 LIMIT 100"

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.

GRAPH.QUERY DEMO_GRAPH
"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.

GRAPH.QUERY DEMO_GRAPH
"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:

GRAPH.QUERY DEMO_GRAPH "MATCH (p:Person {name:'Jim'}) DELETE p"

To delete relationship:

GRAPH.QUERY DEMO_GRAPH "MATCH (: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 .

GRAPH.QUERY DEMO_GRAPH "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.

GRAPH.QUERY DEMO_GRAPH
"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.

GRAPH.QUERY DEMO_GRAPH "MATCH (n { name: 'Jim' }) SET n.name = NULL"

MERGE ¶

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

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.

Any aliases in the MERGE path that were introduced by earlier clauses can only be matched; MERGE will not create them.

When the MERGE path doesn't rely on earlier clauses, the whole path will always either be matched or created.

If all path elements are introduced by MERGE, a match failure will cause all elements to be created, even if part of the match succeeded.

The MERGE path can be followed by ON MATCH SET and ON CREATE SET directives to conditionally set properties depending on whether or not the match succeeded.

Merging nodes

To merge a single node with a label:

GRAPH.QUERY DEMO_GRAPH "MERGE (robert:Critic)"

To merge a single node with properties:

GRAPH.QUERY DEMO_GRAPH "MERGE (charlie { name: 'Charlie Sheen', age: 10 })"

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

GRAPH.QUERY DEMO_GRAPH "MERGE (michael:Person { name: 'Michael Douglas' })""

Merging paths

Because MERGE either matches or creates a full path, it is easy to accidentally create duplicate nodes.

For example, if we run the following query on our sample graph:

GRAPH.QUERY DEMO_GRAPH
"MERGE (charlie { name: 'Charlie Sheen '})-[r:ACTED_IN]->(wallStreet:Movie { name: 'Wall Street' })"

Even though a node with the name 'Charlie Sheen' already exists, the full pattern does not match, so 1 relation and 2 nodes - including a duplicate 'Charlie Sheen' node - will be created.

We should use multiple MERGE clauses to merge a relation and only create non-existent endpoints:

GRAPH.QUERY DEMO_GRAPH
"MERGE (charlie { name: 'Charlie Sheen' })
 MERGE (wallStreet:Movie { name: 'Wall Street' })
 MERGE (charlie)-[r:ACTED_IN]->(wallStreet)"

If we don't want to create anything if pattern elements don't exist, we can combine MATCH and MERGE clauses. The following query merges a relation only if both of its endpoints already exist:

GRAPH.QUERY DEMO_GRAPH
"MATCH (charlie { name: 'Charlie Sheen' })
 MATCH (wallStreet:Movie { name: 'Wall Street' })
 MERGE (charlie)-[r:ACTED_IN]->(wallStreet)"

On Match and On Create directives

Using ON MATCH and ON CREATE, MERGE can set properties differently depending on whether a pattern is matched or created.

In this query, we'll merge paths based on a list of properties and conditionally set a property when creating new entities:

GRAPH.QUERY DEMO_GRAPH
"UNWIND ['Charlie Sheen', 'Michael Douglas', 'Tamara Tunie'] AS actor_name
 MATCH (movie:Movie { name: 'Wall Street' })
 MERGE (person {name: actor_name})-[:ACTED_IN]->(movie)
 ON CREATE SET person.first_role = movie.name"

WITH ¶

The WITH clause allows parts of queries to be independently executed and have their results handled uniquely.

This allows for more flexible query composition as well as data manipulations that would otherwise not be possible in a single query.

If, for example, we wanted to find all children in our graph who are above the average age of all people:

GRAPH.QUERY DEMO_GRAPH
"MATCH (p:Person) WITH AVG(p.age) AS average_age MATCH (:Person)-[:PARENT_OF]->(child:Person) WHERE child.age > average_age return child

This also allows us to use modifiers like DISTINCT , SKIP , LIMIT , and ORDER that otherwise require RETURN clauses.

GRAPH.QUERY DEMO_GRAPH
"MATCH (u:User)  WITH u AS nonrecent ORDER BY u.lastVisit LIMIT 3 SET nonrecent.should_contact = true"

UNWIND ¶

The UNWIND clause breaks down a given list into a sequence of records; each contains a single element in the list.

The order of the records preserves the original list order.

GRAPH.QUERY DEMO_GRAPH
"CREATE (p {array:[1,2,3]})"

GRAPH.QUERY DEMO_GRAPH
"MATCH (p) UNWIND p.array AS y RETURN y"

UNION ¶

The UNION clause is used to combine the result of multiple queries.

UNION combines the results of two or more queries into a single result set that includes all the rows that belong to all queries in the union.

The number and the names of the columns must be identical in all queries combined by using UNION.

To keep all the result rows, use UNION ALL.

Using just UNION will combine and remove duplicates from the result set.

GRAPH.QUERY DEMO_GRAPH
"MATCH (n:Actor) RETURN n.name AS name
UNION ALL
MATCH (n:Movie) RETURN n.title AS name"

Functions ¶

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

• Predicate functions
• Scalar functions
• Aggregating functions
• List functions
• Mathematical functions
• String functions
• Node functions

Predicate functions ¶

Scalar functions ¶

Aggregating functions ¶

List functions ¶

Mathematical functions ¶

String functions ¶

Node functions ¶

Path functions ¶

List comprehensions ¶

List comprehensions are a syntactical construct that accepts an array and produces another based on the provided map and filter directives.

They are a common construct in functional languages and modern high-level languages. In Cypher, they use the syntax:

[element IN array WHERE condition | output elem]

• array can be any expression that produces an array: a literal, a property reference, or a function call.
• WHERE condition is an optional argument to only project elements that pass a certain criteria. If omitted, all elements in the array will be represented in the output.
• | output elem is an optional argument that allows elements to be transformed in the output array. If omitted, the output elements will be the same as their corresponding inputs.

The following query collects all paths of any length, then for each produces an array containing the name property of every node with a rank property greater than 10:

MATCH p=()-[*]->() RETURN [node IN nodes(p) WHERE node.rank > 10 | node.name]

Existential comprehension functions ¶

The functions any() and all() use a simplified form of the list comprehension syntax and return a boolean value.

any(element IN array WHERE condition)

They can operate on any form of input array, but are particularly useful for path filtering. The following query collects all paths of any length in which all traversed edges have a weight less than 3:

MATCH p=()-[*]->() WHERE all(edge IN relationships(p) WHERE edge.weight < 3) RETURN p

Procedures ¶

Procedures are invoked using the syntax:

GRAPH.QUERY social "CALL db.labels()"

Or the variant:

GRAPH.QUERY social "CALL db.labels() YIELD label"

YIELD modifiers are only required if explicitly specified; by default the value in the 'Yields' column will be emitted automatically.

Algorithms ¶

BFS ¶

The breadth-first-search algorithm accepts 4 arguments:

source-node (node) - The root of the search.

max-level (integer) - If greater than zero, this argument indicates how many levels should be traversed by BFS. 1 would retrieve only the source's neighbors, 2 would retrieve all nodes within 2 hops, and so on.

relationship-type (string) - If this argument is NULL, all relationship types will be traversed. Otherwise, it specifies a single relationship type to perform BFS over.

It can yield two outputs:

nodes - An array of all nodes connected to the source without violating the input constraints.

edges - An array of all edges traversed during the search. This does not necessarily contain all edges connecting nodes in the tree, as cycles or multiple edges connecting the same source and destination do not have a bearing on the reachability this algorithm tests for. These can be used to construct the directed acyclic graph that represents the BFS tree. Emitting edges incurs a small performance penalty.

Indexing ¶

RedisGraph supports single-property indexes for node labels. The creation syntax is:

GRAPH.QUERY DEMO_GRAPH "CREATE INDEX ON :Person(age)"

After an index is explicitly created, it will automatically be used by queries that reference that label and any indexed property in a filter.

GRAPH.EXPLAIN G "MATCH (p:Person) WHERE p.age > 80 RETURN p"
1) "Results"
2) "    Project"
3) "        Index Scan | (p:Person)"

This can significantly improve the runtime of queries with very specific filters. An index on :employer(name) , for example, will dramatically benefit the query:

GRAPH.QUERY DEMO_GRAPH
"MATCH (:Employer {name: 'Dunder Mifflin'})-[:EMPLOYS]->(p:Person) RETURN p"

RedisGraph can use multiple indexes as ad-hoc composite indexes at query time. For example, if age and years_employed are both indexed, then both indexes will be utilized in the query:

GRAPH.QUERY DEMO_GRAPH
"MATCH (p:Person) WHERE p.age < 30 OR p.years_employed < 3 RETURN p"

Individual indexes can be deleted using the matching syntax:

GRAPH.QUERY DEMO_GRAPH "DROP INDEX ON :Person(age)"

Full-text indexes ¶

RedisGraph leverages the indexing capabilities of RediSearch to provide full-text indices through procedure calls. To construct a full-text index on the title property of all nodes with label Movie , use the syntax:

GRAPH.QUERY DEMO_GRAPH "CALL db.idx.fulltext.createNodeIndex('Movie', 'title')"

(More properties can be added to this index by adding their names to the above set of arguments, or using this syntax again with the additional names.)

Now this index can be invoked to match any whole words contained within:

GRAPH.QUERY DEMO_GRAPH
"CALL db.idx.fulltext.queryNodes('Movie', 'Book') YIELD node RETURN node.title"
1) 1) "node.title"
2) 1) 1) "The Jungle Book"
   2) 1) "The Book of Life"
3) 1) "Query internal execution time: 0.927409 milliseconds"

This CALL clause can be interleaved with other Cypher clauses to perform more elaborate manipulations:

GRAPH.QUERY DEMO_GRAPH
"CALL db.idx.fulltext.queryNodes('Movie', 'Book') YIELD node AS m
WHERE m.genre = 'Adventure'
RETURN m ORDER BY m.rating"
1) 1) "m"
2) 1) 1) 1) 1) "id"
            2) (integer) 1168
         2) 1) "labels"
            2) 1) "Movie"
         3) 1) "properties"
            2) 1) 1) "genre"
                  2) "Adventure"
               2) 1) "rating"
                  2) "7.6"
               3) 1) "votes"
                  2) (integer) 151342
               4) 1) "year"
                  2) (integer) 2016
               5) 1) "title"
                  2) "The Jungle Book"
3) 1) "Query internal execution time: 0.226914 milliseconds"

GRAPH.PROFILE ¶

Executes a query and produces an execution plan augmented with metrics for each operation's execution.

Arguments: Graph name, Query

Returns: String representation of a query execution plan, with details on results produced by and time spent in each operation.

GRAPH.PROFILE is a parallel entrypoint to GRAPH.QUERY . It accepts and executes the same queries, but it will not emit results, instead returning the operation tree structure alongside the number of records produced and total runtime of each operation.

It is important to note that this blends elements of GRAPH.QUERY and GRAPH.EXPLAIN . It is not a dry run and will perform all graph modifications expected of the query, but will not output results produced by a RETURN clause or query statistics.

GRAPH.PROFILE imdb
"MATCH (actor_a:Actor)-[:ACT]->(:Movie)<-[:ACT]-(actor_b:Actor)
WHERE actor_a <> actor_b
CREATE (actor_a)-[:COSTARRED_WITH]->(actor_b)"
1) "Create | Records produced: 11208, Execution time: 168.208661 ms"
2) "    Filter | Records produced: 11208, Execution time: 1.250565 ms"
3) "        Conditional Traverse | Records produced: 12506, Execution time: 7.705860 ms"
4) "            Node By Label Scan | (actor_a:Actor) | Records produced: 1317, Execution time: 0.104346 ms"

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:

GRAPH.QUERY DEMO_GRAPH "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"

GRAPH.SLOWLOG ¶

Returns a list containing up to 10 of the slowest queries issued against the given graph ID.

Each item in the list has the following structure:

1. A unix timestamp at which the log entry was processed.
2. The issued command.
3. The issued query.
4. The amount of time needed for its execution, in milliseconds.

GRAPH.SLOWLOG graph_id
 1) 1) "1581932396"
    2) "GRAPH.QUERY"
    3) "MATCH (a:Person)-[:FRIEND]->(e) RETURN e.name"
    4) "0.831"
 2) 1) "1581932396"
    2) "GRAPH.QUERY"
    3) "MATCH (me:Person)-[:FRIEND]->(:Person)-[:FRIEND]->(fof:Person) RETURN fof.name"
    4) "0.288"