ORDER BY

Introduction

ORDER BY relies on comparisons to sort the output, see Ordering and comparison of values. You can sort on many different values, e.g. node/relationship properties, the node/relationship ids, or on most expressions. If you do not specify what to sort on, there is a risk that the results are arbitrarily sorted and therefore it is best practice to be specific when using ORDER BY.

In terms of scope of variables, ORDER BY follows special rules, depending on if the projecting RETURN or WITH clause is either aggregating or DISTINCT. If it is an aggregating or DISTINCT projection, only the variables available in the projection are available. If the projection does not alter the output cardinality (which aggregation and DISTINCT do), variables available from before the projecting clause are also available. When the projection clause shadows already existing variables, only the new variables are available.

Lastly, it is not allowed to use aggregating expressions in the ORDER BY sub-clause if they are not also listed in the projecting clause. This last rule is to make sure that ORDER BY does not change the results, only the order of them.

The performance of Cypher queries using ORDER BY on node properties can be influenced by the existence and use of an index for finding the nodes. If the index can provide the nodes in the order requested in the query, Cypher can avoid the use of an expensive Sort operation. Read more about this capability in The use of indexes.

The following graph is used for the examples below:

Diagram

Strings that contain special characters can have inconsistent or non-deterministic ordering in Neo4j. For details, see Sorting of special characters.

Order nodes by property

ORDER BY is used to sort the output.

Query
MATCH (n)
RETURN n.name, n.age
ORDER BY n.name

The nodes are returned, sorted by their name.

Table 1. Result
n.name n.age

"A"

34

"B"

36

"C"

32

Rows: 3

Order nodes by multiple properties

You can order by multiple properties by stating each variable in the ORDER BY clause. Cypher will sort the result by the first variable listed, and for equals values, go to the next property in the ORDER BY clause, and so on.

Query
MATCH (n)
RETURN n.name, n.age
ORDER BY n.age, n.name

This returns the nodes, sorted first by their age, and then by their name.

Table 2. Result
n.name n.age

"C"

32

"A"

34

"B"

36

Rows: 3

Order nodes by id

ORDER BY is used to sort the output.

Query
MATCH (n)
RETURN n.name, n.age
ORDER BY id(n)

The nodes are returned, sorted by their internal id.

Table 3. Result
n.name n.age

"A"

34

"B"

36

"C"

32

Rows: 3

Keep in mind that Neo4j reuses its internal ids when nodes and relationships are deleted. This means that applications using, and relying on, internal Neo4j ids, are brittle or at risk of making mistakes. It is therefore recommended to use application-generated ids instead.

Order nodes by expression

ORDER BY is used to sort the output.

Query
MATCH (n)
RETURN n.name, n.age, n.length
ORDER BY keys(n)

The nodes are returned, sorted by their properties.

Table 4. Result
n.name n.age n.length

"A"

34

170

"C"

32

185

"B"

36

<null>

Rows: 3

Order nodes in descending order

By adding DESC[ENDING] after the variable to sort on, the sort will be done in reverse order.

Query
MATCH (n)
RETURN n.name, n.age
ORDER BY n.name DESC

The example returns the nodes, sorted by their name in reverse order.

Table 5. Result
n.name n.age

"C"

32

"B"

36

"A"

34

Rows: 3

Ordering null

When sorting the result set, null will always come at the end of the result set for ascending sorting, and first when doing descending sort.

Query
MATCH (n)
RETURN n.length, n.name, n.age
ORDER BY n.length

The nodes are returned sorted by the length property, with a node without that property last.

Table 6. Result
n.length n.name n.age

170

"A"

34

185

"C"

32

<null>

"B"

36

Rows: 3

Ordering in a WITH clause

When ORDER BY is present on a WITH clause , the immediately following clause will receive records in the specified order. The order is not guaranteed to be retained after the following clause, unless that also has an ORDER BY subclause. The ordering guarantee can be useful to exploit by operations which depend on the order in which they consume values. For example, this can be used to control the order of items in the list produced by the collect() aggregating function. The MERGE and SET clauses also have ordering dependencies which can be controlled this way.

Query
MATCH (n)
WITH n ORDER BY n.age
RETURN collect(n.name) AS names

The list of names built from the collect aggregating function contains the names in order of the age property.

Table 7. Result
names

["C","A","B"]

Rows: 1