nGQL cheatsheet¶
Functions¶
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Function Description double abs(double x) Returns the absolute value of the argument. double floor(double x) Returns the largest integer value smaller than or equal to the argument. (Rounds down) double ceil(double x) Returns the smallest integer greater than or equal to the argument. (Rounds up) double round(double x) Returns the integer value nearest to the argument. Returns a number farther away from 0 if the argument is in the middle. double sqrt(double x) Returns the square root of the argument. double cbrt(double x) sReturns the cubic root of the argument. double hypot(double x, double y) Returns the hypotenuse of a right-angled triangle. double pow(double x, double y) Returns the result of \(x^y\). double exp(double x) Returns the result of \(e^x\). double exp2(double x) Returns the result of \(2^x\). double log(double x) Returns the base-e logarithm of the argument. double log2(double x) Returns the base-2 logarithm of the argument. double log10(double x) Returns the base-10 logarithm of the argument. double sin(double x) Returns the sine of the argument. double asin(double x) Returns the inverse sine of the argument. double cos(double x) Returns the cosine of the argument. double acos(double x) Returns the inverse cosine of the argument. double tan(double x) Returns the tangent of the argument. double atan(double x) Returns the inverse tangent of the argument. double rand() Returns a random floating point number in the range from 0 (inclusive) to 1 (exclusive); i.e.[0,1). int rand32(int min, int max) Returns a random 32-bit integer in [min, max)
.
If you set only one argument, it is parsed asmax
andmin
is0
by default.
If you set no argument, the system returns a random signed 32-bit integer.int rand64(int min, int max) Returns a random 64-bit integer in [min, max)
.
If you set only one argument, it is parsed asmax
andmin
is0
by default.
If you set no argument, the system returns a random signed 64-bit integer.collect() Puts all the collected values into a list. avg() Returns the average value of the argument. count() Returns the number of records. max() Returns the maximum value. min() Returns the minimum value. std() Returns the population standard deviation. sum() Returns the sum value. bit_and() Bitwise AND. bit_or() Bitwise OR. bit_xor() Bitwise XOR. int size() Returns the number of elements in a list or a map. int range(int start, int end, int step) Returns a list of integers from [start,end]
in the specified steps.step
is 1 by default.int sign(double x) Returns the signum of the given number.
If the number is 0, the system returns 0.
If the number is negative, the system returns -1.
If the number is positive, the system returns 1.double e() Returns the base of the natural logarithm, e (2.718281828459045). double pi() Returns the mathematical constant pi (3.141592653589793). double radians() Converts degrees to radians. radians(180)
returns3.141592653589793
.
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Function Description int strcasecmp(string a, string b) Compares string a and b without case sensitivity. When a = b, the return value is 0. When a > b, the return value is greater than 0. When a < b, the return value is less than 0. string lower(string a) Returns the argument in lowercase. string toLower(string a) The same as lower()
.string upper(string a) Returns the argument in uppercase. string toUpper(string a) The same as upper()
.int length(string a) Returns the length of the given string in bytes. string trim(string a) Removes leading and trailing spaces. string ltrim(string a) Removes leading spaces. string rtrim(string a) Removes trailing spaces. string left(string a, int count) Returns a substring consisting of count
characters from the left side of string a. If string a is shorter thancount
, the system returns string a.string right(string a, int count) Returns a substring consisting of count
characters from the right side of string a. If string a is shorter thancount
, the system returns string a.string lpad(string a, int size, string letters) Left-pads string a with string letters
and returns a substring with the length ofsize
.string rpad(string a, int size, string letters) Right-pads string a with string letters
and returns a substring with the length ofsize
.string substr(string a, int pos, int count) Returns a substring extracting count
characters starting from the specified positionpos
of string a.string substring(string a, int pos, int count) The same as substr()
.string reverse(string) Returns a string in reverse order. string replace(string a, string b, string c) Replaces string b in string a with string c. list split(string a, string b) Splits string a at string b and returns a list of strings. string toString() Takes in any data type and converts it into a string. int hash() Takes in any data type and encodes it into a hash value.
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Function Description int now() Returns the current date and time of the system time zone. timestamp timestamp() Returns the current date and time of the system time zone. date date() Returns the current UTC date based on the current system. time time() Returns the current UTC time based on the current system. datetime datetime() Returns the current UTC date and time based on the current system.
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Function Description id(vertex) Returns the ID of a vertex. The data type of the result is the same as the vertex ID. map properties(vertex) Returns the properties of a vertex. map properties(edge) Returns the properties of an edge. string type(edge) Returns the edge type of an edge. src(edge) Returns the source vertex ID of an edge. The data type of the result is the same as the vertex ID. dst(edge) Returns the destination vertex ID of an edge. The data type of the result is the same as the vertex ID. int rank(edge) Returns the rank value of an edge.
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Function Description keys(expr) Returns a list containing the string representations for all the property names of vertices, edges, or maps. labels(vertex) Returns the list containing all the tags of a vertex. nodes(path) Returns the list containing all the vertices in a path. range(start, end [, step]) Returns the list containing all the fixed-length steps in [start,end]
.step
is 1 by default.relationships(path) Returns the list containing all the relationships in a path. reverse(list) Returns the list reversing the order of all elements in the original list. tail(list) Returns all the elements of the original list, excluding the first one. head(list) Returns the first element of a list. last(list) Returns the last element of a list. coalesce(list) Returns the first not null value in a list. reduce() See reduce() function。
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Function Description count() Syntax: count({expr | *})
.count()
returns the number of rows (including NULL).
count(expr)
returns the number of non-NULL values that meet the expression.
count() and size() are different.
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Function Description collect() The collect() function returns a list containing the values returned by an expression. Using this function aggregates data by merging multiple records or values into a single list.
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Function Syntax Description reduce() reduce(<accumulator> = <initial>, <variable> IN <list> | <expression>)
The reduce()
function applies an expression to each element in a list one by one, chains the result to the next iteration by taking it as the initial value, and returns the final result.
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Function Description hash() The hash()
function returns the hash value of the argument. The argument can be a number, a string, a list, a boolean, null, or an expression that evaluates to a value of the preceding data types. The source code of thehash()
function (MurmurHash2), seed (0xc70f6907UL
), and other parameters can be found inMurmurHash2.h
.
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Function Description concat() The concat()
function requires at least two or more strings. All the parameters are concatenated into one string.
Syntax:concat(string1,string2,...)
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Function Description concat_ws() The concat_ws()
function connects two or more strings with a predefined separator.
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Predicate functions return
true
orfalse
. They are most commonly used inWHERE
clauses.<predicate>(<variable> IN <list> WHERE <condition>)
Functions Description exists() Returns true
if the specified property exists in the vertex, edge or map. Otherwise, returnsfalse
.any() Returns true
if the specified predicate holds for at least one element in the given list. Otherwise, returnsfalse
.all() Returns true
if the specified predicate holds for all elements in the given list. Otherwise, returnsfalse
.none() Returns true
if the specified predicate holds for no element in the given list. Otherwise, returnsfalse
.single() Returns true
if the specified predicate holds for exactly one of the elements in the given list. Otherwise, returnsfalse
.
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The
CASE
expression uses conditions to filter the result of an nGQL query statement. It is usually used in theYIELD
andRETURN
clauses. TheCASE
expression will traverse all the conditions. When the first condition is met, theCASE
expression stops reading the conditions and returns the result. If no conditions are met, it returns the result in theELSE
clause. If there is noELSE
clause and no conditions are met, it returnsNULL
.Syntax:
CASE <comparer> WHEN <value> THEN <result> [WHEN ...] [ELSE <default>] END
Parameter | Description |
---|---|
comparer |
A value or a valid expression that outputs a value. This value is used to compare with the value . |
value |
It will be compared with the comparer . If the value matches the comparer , then this condition is met. |
result |
The result is returned by the CASE expression if the value matches the comparer . |
default |
The default is returned by the CASE expression if no conditions are met. |
General queries statements¶
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MATCH <pattern> [<WHERE clause>] RETURN <output>
Pattern Example Description Match vertices (v)
You can use a user-defined variable in a pair of parentheses to represent a vertex in a pattern. For example: (v)
.Match tags MATCH (v:player) RETURN v
You can specify a tag with :<tag_name>
after the vertex in a pattern.Match vertex properties MATCH (v:player{name:"Tim Duncan"}) RETURN v
You can specify a vertex property with {<prop_name>: <prop_value>}
after the tag in a pattern.Match a VID. MATCH (v) WHERE id(v) == 'player101' RETURN v
You can use the VID to match a vertex. The id()
function can retrieve the VID of a vertex.Match multiple VIDs. MATCH (v:player { name: 'Tim Duncan' })--(v2) WHERE id(v2) IN ["player101", "player102"] RETURN v2
To match multiple VIDs, use WHERE id(v) IN [vid_list]
.Match connected vertices MATCH (v:player{name:"Tim Duncan"})--(v2) RETURN v2.name AS Name
You can use the --
symbol to represent edges of both directions and match vertices connected by these edges. You can add a>
or<
to the--
symbol to specify the direction of an edge.Match paths MATCH p=(v:player{name:"Tim Duncan"})-->(v2) RETURN p
Connected vertices and edges form a path. You can use a user-defined variable to name a path as follows. Match edges MATCH (v:player{name:"Tim Duncan"})-[e]-(v2) RETURN e
Besides using --
,-->
, or<--
to indicate a nameless edge, you can use a user-defined variable in a pair of square brackets to represent a named edge. For example:-[e]-
.Match an edge type MATCH ()-[e:follow]-() RETURN e
Just like vertices, you can specify an edge type with :<edge_type>
in a pattern. For example:-[e:follow]-
.Match edge type properties MATCH (v:player{name:"Tim Duncan"})-[e:follow{degree:95}]->(v2) RETURN e
You can specify edge type properties with {<prop_name>: <prop_value>}
in a pattern. For example:[e:follow{likeness:95}]
.Match multiple edge types MATCH (v:player{name:"Tim Duncan"})-[e:follow | :serve]->(v2) RETURN e
The |
symbol can help matching multiple edge types. For example:[e:follow|:serve]
. The English colon (:) before the first edge type cannot be omitted, but the English colon before the subsequent edge type can be omitted, such as[e:follow|serve]
.Match multiple edges MATCH (v:player{name:"Tim Duncan"})-[]->(v2)<-[e:serve]-(v3) RETURN v2, v3
You can extend a pattern to match multiple edges in a path. Match fixed-length paths MATCH p=(v:player{name:"Tim Duncan"})-[e:follow*2]->(v2) RETURN DISTINCT v2 AS Friends
You can use the :<edge_type>*<hop>
pattern to match a fixed-length path.hop
must be a non-negative integer.Match variable-length paths MATCH p=(v:player{name:"Tim Duncan"})-[e:follow*1..3]->(v2) RETURN v2 AS Friends
minHop
: Optional. It represents the minimum length of the path.minHop
: must be a non-negative integer. The default value is 1.maxHop
: Required. It represents the maximum length of the path.maxHop
must be a non-negative integer. It has no default value.Match variable-length paths with multiple edge types MATCH p=(v:player{name:"Tim Duncan"})-[e:follow | serve*2]->(v2) RETURN DISTINCT v2
You can specify multiple edge types in a fixed-length or variable-length pattern. In this case, hop
,minHop
, andmaxHop
take effect on all edge types.Retrieve vertex or edge information MATCH (v:player{name:"Tim Duncan"}) RETURN v
MATCH (v:player{name:"Tim Duncan"})-[e]->(v2) RETURN e
Use RETURN {<vertex_name> | <edge_name>}
to retrieve all the information of a vertex or an edge.Retrieve VIDs MATCH (v:player{name:"Tim Duncan"}) RETURN id(v)
Use the id()
function to retrieve VIDs.Retrieve tags MATCH (v:player{name:"Tim Duncan"}) RETURN labels(v)
Use the labels()
function to retrieve the list of tags on a vertex.
To retrieve the nth element in thelabels(v)
list, uselabels(v)[n-1]
.Retrieve a single property on a vertex or an edge MATCH (v:player{name:"Tim Duncan"}) RETURN v.age
Use RETURN {<vertex_name> | <edge_name>}.<property>
to retrieve a single property.
UseAS
to specify an alias for a property.Retrieve all properties on a vertex or an edge MATCH p=(v:player{name:"Tim Duncan"})-[]->(v2) RETURN properties(v2)
Use the properties()
function to retrieve all properties on a vertex or an edge.Retrieve edge types MATCH p=(v:player{name:"Tim Duncan"})-[e]->() RETURN DISTINCT type(e)
Use the type()
function to retrieve the matched edge types.Retrieve paths MATCH p=(v:player{name:"Tim Duncan"})-[*3]->() RETURN p
Use RETURN <path_name>
to retrieve all the information of the matched paths.Retrieve vertices in a path MATCH p=(v:player{name:"Tim Duncan"})-[]->(v2) RETURN nodes(p)
Use the nodes()
function to retrieve all vertices in a path.Retrieve edges in a path MATCH p=(v:player{name:"Tim Duncan"})-[]->(v2) RETURN relationships(p)
Use the relationships()
function to retrieve all edges in a path.Retrieve path length MATCH p=(v:player{name:"Tim Duncan">})-[*..2]->(v2) RETURN p AS Paths, length(p) AS Length
Use the length()
function to retrieve the length of a path.
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LOOKUP ON {<vertex_tag> | <edge_type>} [WHERE <expression> [AND <expression> ...]] [YIELD <return_list> [AS <alias>]]
Pattern Example Description Retrieve vertices LOOKUP ON player WHERE player.name == "Tony Parker" YIELD player.name AS name, player.age AS age
The following example returns vertices whose name
isTony Parker
and the tag isplayer
.Retrieve edges LOOKUP ON follow WHERE follow.degree == 90 YIELD follow.degree
Returns edges whose degree
is90
and the edge type isfollow
.List vertices with a tag LOOKUP ON player
Shows how to retrieve the VID of all vertices tagged with player
.List edges with an edge types LOOKUP ON like
Shows how to retrieve the source Vertex IDs, destination vertex IDs, and ranks of all edges of the like
edge type.Count the numbers of vertices or edges LOOKUP ON player | YIELD COUNT(*) AS Player_Number
Shows how to count the number of vertices tagged with player
.Count the numbers of edges LOOKUP ON like | YIELD COUNT(*) AS Like_Number
Shows how to count the number of edges of the like
edge type.
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GO [[<M> TO] <N> STEPS ] FROM <vertex_list> OVER <edge_type_list> [{REVERSELY | BIDIRECT}] [ WHERE <conditions> ] [YIELD [DISTINCT] <return_list>] [| GROUP BY {col_name | expr | position} YIELD <col_name>] [| ORDER BY <expression> [{ASC | DESC}]] [| LIMIT [<offset_value>,] <number_rows>]
Example Description GO FROM "player102" OVER serve
Returns the teams that player 102 serves. GO 2 STEPS FROM "player102" OVER follow
Returns the friends of player 102 with 2 hops. GO FROM "player100", "player102" OVER serve WHERE properties(edge).start_year > 1995 YIELD DISTINCT properties($$).name AS team_name, properties(edge).start_year AS start_year, properties($^).name AS player_name
Adds a filter for the traversal. GO FROM "player100" OVER follow, serve YIELD properties(edge).degree, properties(edge).start_year
The following example traverses along with multiple edge types. If there is no value for a property, the output is UNKNOWN_PROP
.GO FROM "player100" OVER follow REVERSELY YIELD src(edge) AS destination
The following example returns the neighbor vertices in the incoming direction of player 100. GO FROM "player100" OVER follow REVERSELY YIELD src(edge) AS id | GO FROM $-.id OVER serve WHERE properties($^).age > 20 YIELD properties($^).name AS FriendOf, properties($$).name AS Team
The following example retrieves the friends of player 100 and the teams that they serve. GO FROM "player102" OVER follow YIELD dst(edge) AS both
The following example returns all the neighbor vertices of player 102. GO 2 STEPS FROM "player100" OVER follow YIELD src(edge) AS src, dst(edge) AS dst, properties($$).age AS age | GROUP BY $-.dst YIELD $-.dst AS dst, collect_set($-.src) AS src, collect($-.age) AS age
The following example the outputs according to age.
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FETCH PROP ON {<tag_name>[, tag_name ...] | *} <vid> [, vid ...] [YIELD <return_list> [AS <alias>]]
Example Description FETCH PROP ON player "player100"
Specify a tag in the FETCH
statement to fetch the vertex properties by that tag.FETCH PROP ON player "player100" YIELD player.name AS name
Use a YIELD
clause to specify the properties to be returned.FETCH PROP ON player "player101", "player102", "player103"
Specify multiple VIDs (vertex IDs) to fetch properties of multiple vertices. Separate the VIDs with commas. FETCH PROP ON player, t1 "player100", "player103"
Specify multiple tags in the FETCH
statement to fetch the vertex properties by the tags. Separate the tags with commas.FETCH PROP ON * "player100", "player106", "team200"
Set an asterisk symbol *
to fetch properties by all tags in the current graph space.FETCH PROP ON serve "player102" -> "player106" YIELD dst(edge)
Syntax: FETCH PROP ON <edge_type> <src_vid> -> <dst_vid>[@<rank>] [, <src_vid> -> <dst_vid> ...] [YIELD <output>]
FETCH PROP ON serve "player100" -> "team204"
The following statement fetches all the properties of the serve
edge that connects vertex"player100"
and vertex"team204"
.FETCH PROP ON serve "player100" -> "team204" YIELD serve.start_year
Use a YIELD
clause to fetch specific properties of an edge.FETCH PROP ON serve "player100" -> "team204", "player133" -> "team202"
Specify multiple edge patterns ( <src_vid> -> <dst_vid>[@<rank>]
) to fetch properties of multiple edges. Separate the edge patterns with commas.FETCH PROP ON serve "player100" -> "team204"@1
To fetch on an edge whose rank is not 0, set its rank in the FETCH statement. GO FROM "player101" OVER follow YIELD follow._src AS s, follow._dst AS d | FETCH PROP ON follow $-.s -> $-.d YIELD follow.degree
The following statement returns the degree
values of thefollow
edges that start from vertex"player101"
.$var = GO FROM "player101" OVER follow YIELD follow._src AS s, follow._dst AS d; FETCH PROP ON follow $var.s -> $var.d YIELD follow.degree
You can use user-defined variables to construct similar queries.
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UNWIND <list> AS <alias> <RETURN clause>
Example Description UNWIND [1,2,3] AS n RETURN n
The following example splits the list [1,2,3]
into three rows.WITH [1,1,2,2,3,3] AS n UNWIND n AS r WITH DISTINCT r AS r ORDER BY r RETURN collect(r)
1. Splits the list [1,1,2,2,3,3]
into rows. 2. Removes duplicated rows. 3. Sorts the rows. 4. Transforms the rows to a list.MATCH p=(v:player{name:"Tim Duncan"})--(v2) WITH nodes(p) AS n UNWIND n AS r WITH DISTINCT r AS r RETURN collect(r)
1. Outputs the vertices on the matched path into a list. 2. Splits the list into rows. 3. Removes duplicated rows. 4. Transforms the rows to a list.
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SHOW
Statement Syntax Example Description SHOW CHARSET SHOW CHARSET
SHOW CHARSET
Shows the available character sets. SHOW COLLATION SHOW COLLATION
SHOW COLLATION
Shows the collations supported by Nebula Graph. SHOW CREATE SPACE SHOW CREATE SPACE <space_name>
SHOW CREATE SPACE basketballplayer
Shows the creating statement of the specified graph space. SHOW CREATE TAG/EDGE SHOW CREATE {TAG <tag_name> | EDGE <edge_name>}
SHOW CREATE TAG player
Shows the basic information of the specified tag. SHOW HOSTS SHOW HOSTS [GRAPH | STORAGE | META]
SHOW HOSTS
SHOW HOSTS GRAPH
Shows the host and version information of Graph Service, Storage Service, and Meta Service. SHOW INDEX STATUS SHOW {TAG | EDGE} INDEX STATUS
SHOW TAG INDEX STATUS
Shows the status of jobs that rebuild native indexes, which helps check whether a native index is successfully rebuilt or not. SHOW INDEXES SHOW {TAG | EDGE} INDEXES
SHOW TAG INDEXES
Shows the names of existing native indexes. SHOW PARTS SHOW PARTS [<part_id>]
SHOW PARTS
Shows the information of a specified partition or all partitions in a graph space. SHOW ROLES SHOW ROLES IN <space_name>
SHOW ROLES in basketballplayer
Shows the roles that are assigned to a user account. SHOW SNAPSHOTS SHOW SNAPSHOTS
SHOW SNAPSHOTS
Shows the information of all the snapshots. SHOW SPACES SHOW SPACES
SHOW SPACES
Shows existing graph spaces in Nebula Graph. SHOW STATS SHOW STATS
SHOW STATS
Shows the statistics of the graph space collected by the latest STATS
job.SHOW TAGS/EDGES SHOW TAGS | EDGES
SHOW TAGS
、SHOW EDGES
Shows all the tags in the current graph space. SHOW USERS SHOW USERS
SHOW USERS
Shows the user information. SHOW SESSIONS SHOW SESSIONS
SHOW SESSIONS
Shows the information of all the sessions. SHOW SESSIONS SHOW SESSION <Session_Id>
SHOW SESSION 1623304491050858
Shows a specified session with its ID. SHOW QUERIES SHOW [ALL] QUERIES
SHOW QUERIES
Shows the information of working queries in the current session. SHOW META LEADER SHOW META LEADER
SHOW META LEADER
Shows the information of the leader in the current Meta cluster.
Clauses and options¶
Clause | Syntax | Example | Description |
---|---|---|---|
GROUP BY | GROUP BY <var> YIELD <var>, <aggregation_function(var)> |
GO FROM "player100" OVER follow BIDIRECT YIELD $$.player.name as Name | GROUP BY $-.Name YIELD $-.Name as Player, count(*) AS Name_Count |
Finds all the vertices connected directly to vertex "player100" , groups the result set by player names, and counts how many times the name shows up in the result set. |
LIMIT | YIELD <var> [| LIMIT [<offset_value>,] <number_rows>] |
O FROM "player100" OVER follow REVERSELY YIELD $$.player.name AS Friend, $$.player.age AS Age | ORDER BY $-.Age, $-.Friend | LIMIT 1, 3 |
Returns the 3 rows of data starting from the second row of the sorted output. |
SKIP | RETURN <var> [SKIP <offset>] [LIMIT <number_rows>] |
MATCH (v:player{name:"Tim Duncan"}) --> (v2) RETURN v2.name AS Name, v2.age AS Age ORDER BY Age DESC SKIP 1 |
SKIP can be used alone to set the offset and return the data after the specified position. |
ORDER BY | <YIELD clause> ORDER BY <expression> [ASC | DESC] [, <expression> [ASC | DESC] ...] |
FETCH PROP ON player "player100", "player101", "player102", "player103" YIELD player.age AS age, player.name AS name | ORDER BY $-.age ASC, $-.name DESC |
The ORDER BY clause specifies the order of the rows in the output. |
RETURN | RETURN {<vertex_name>|<edge_name>|<vertex_name>.<property>|<edge_name>.<property>|...} |
MATCH (v:player) RETURN v.name, v.age LIMIT 3 |
Returns the first three rows with values of the vertex properties name and age . |
TTL | CREATE TAG <tag_name>(<property_name_1> <property_value_1>, <property_name_2> <property_value_2>, ...) ttl_duration= <value_int>, ttl_col = <property_name> |
CREATE TAG t2(a int, b int, c string) ttl_duration= 100, ttl_col = "a" |
Create a tag and set the TTL options. |
WHERE | WHERE {<vertex|edge_alias>.<property_name> {>|==|<|...} <value>...} |
MATCH (v:player) WHERE v.name == "Tim Duncan" XOR (v.age < 30 AND v.name == "Yao Ming") OR NOT (v.name == "Yao Ming" OR v.name == "Tim Duncan") RETURN v.name, v.age |
The WHERE clause filters the output by conditions. The WHERE clause usually works in Native nGQL GO and LOOKUP statements, and OpenCypher MATCH and WITH statements. |
YIELD | YIELD [DISTINCT] <col> [AS <alias>] [, <col> [AS <alias>] ...] [WHERE <conditions>]; |
GO FROM "player100" OVER follow YIELD dst(edge) AS ID | FETCH PROP ON player $-.ID YIELD player.age AS Age | YIELD AVG($-.Age) as Avg_age, count(*)as Num_friends |
Finds the players that "player100" follows and calculates their average age. |
WITH | MATCH $expressions WITH {nodes()|labels()|...} |
MATCH p=(v:player{name:"Tim Duncan"})--() WITH nodes(p) AS n UNWIND n AS n1 RETURN DISTINCT n1 |
The WITH clause can retrieve the output from a query part, process it, and pass it to the next query part as the input. |
Space statements¶
Statement | Syntax | Example | Description |
---|---|---|---|
CREATE SPACE | CREATE SPACE [IF NOT EXISTS] <graph_space_name> ( [partition_num = <partition_number>,] [replica_factor = <replica_number>,] vid_type = {FIXED_STRING(<N>)| INT[64]} ) [COMMENT = '<comment>'] |
CREATE SPACE my_space_1 (vid_type=FIXED_STRING(30)) |
Creates a graph space with |
CREATE SPACE | CREATE SPACE <new_graph_space_name> AS <old_graph_space_name> |
CREATE SPACE my_space_4 as my_space_3 |
Clone a graph space. |
USE | USE <graph_space_name> |
USE space1 |
Specifies a graph space as the current working graph space for subsequent queries. |
SHOW SPACES | SHOW SPACES |
SHOW SPACES |
Lists all the graph spaces in the Nebula Graph examples. |
DESCRIBE SPACE | DESC[RIBE] SPACE <graph_space_name> |
DESCRIBE SPACE basketballplayer |
Returns the information about the specified graph space.息。 |
DROP SPACE | DROP SPACE [IF EXISTS] <graph_space_name> |
DROP SPACE basketballplayer |
Deletes everything in the specified graph space. |
TAG statements¶
Statement | Syntax | Example | Description |
---|---|---|---|
CREATE TAG | CREATE TAG [IF NOT EXISTS] <tag_name> ( <prop_name> <data_type> [NULL | NOT NULL] [DEFAULT <default_value>] [COMMENT '<comment>'] [{, <prop_name> <data_type> [NULL | NOT NULL] [DEFAULT <default_value>] [COMMENT '<comment>']} ...] ) [TTL_DURATION = <ttl_duration>] [TTL_COL = <prop_name>] [COMMENT = '<comment>'] |
CREATE TAG woman(name string, age int, married bool, salary double, create_time timestamp) TTL_DURATION = 100, TTL_COL = "create_time" |
Creates a tag with the given name in a graph space. |
DROP TAG | DROP TAG [IF EXISTS] <tag_name> |
CREATE TAG test(p1 string, p2 int) |
Drops a tag with the given name in the current working graph space. |
ALTER TAG | ALTER TAG <tag_name> <alter_definition> [, alter_definition] ...] [ttl_definition [, ttl_definition] ... ] [COMMENT = '<comment>'] |
ALTER TAG t1 ADD (p3 int, p4 string) |
Alters the structure of a tag with the given name in a graph space. You can add or drop properties, and change the data type of an existing property. You can also set a [TTL](../3.ngql-guide/8.clauses-and-options/ttl-options.md(Time-To-Live)on a property, or change its TTL duration. |
SHOW TAGS | SHOW TAGS |
SHOW TAGS |
Shows the name of all tags in the current graph space. |
DESCRIBE TAG | DESC[RIBE] TAG <tag_name> |
DESCRIBE TAG player |
Returns the information about a tag with the given name in a graph space, such as field names, data type, and so on. |
DELETE TAG | DELETE TAG <tag_name_list> FROM <VID> |
DELETE TAG test1 FROM "test" |
Deletes a tag with the given name on a specified vertex. |
Edge type statements¶
Statement | Syntax | Example | Description |
---|---|---|---|
CREATE EDGE | CREATE EDGE [IF NOT EXISTS] <edge_type_name> ( <prop_name> <data_type> [NULL | NOT NULL] [DEFAULT <default_value>] [COMMENT '<comment>'] [{, <prop_name> <data_type> [NULL | NOT NULL] [DEFAULT <default_value>] [COMMENT '<comment>']} ...] ) [TTL_DURATION = <ttl_duration>] [TTL_COL = <prop_name>] [COMMENT = '<comment>'] |
CREATE EDGE e1(p1 string, p2 int, p3 timestamp) TTL_DURATION = 100, TTL_COL = "p2" |
Creates an edge type with the given name in a graph space.type。 |
DROP EDGE | DROP EDGE [IF EXISTS] <edge_type_name> |
DROP EDGE e1 |
Drops an edge type with the given name in a graph space. |
ALTER EDGE | ALTER EDGE <edge_type_name> <alter_definition> [, alter_definition] ...] [ttl_definition [, ttl_definition] ... ] [COMMENT = '<comment>'] |
ALTER EDGE e1 ADD (p3 int, p4 string) |
Alters the structure of an edge type with the given name in a graph space. |
SHOW EDGES | SHOW EDGES |
SHOW EDGES |
Shows all edge types in the current graph space. |
DESCRIBE EDGE | DESC[RIBE] EDGE <edge_type_name> |
DESCRIBE EDGE follow |
Returns the information about an edge type with the given name in a graph space, such as field names, data type, and so on. |
Vertex statements¶
Statement | Syntax | Example | Description |
---|---|---|---|
INSERT VERTEX | INSERT VERTEX [IF NOT EXISTS] <tag_name> (<prop_name_list>) [, <tag_name> (<prop_name_list>), ...] {VALUES | VALUE} VID: (<prop_value_list>[, <prop_value_list>]) |
INSERT VERTEX t2 (name, age) VALUES "13":("n3", 12), "14":("n4", 8) |
Inserts one or more vertices into a graph space in Nebula Graph. |
DELETE VERTEX | DELETE VERTEX <vid> [, <vid> ...] |
DELETE VERTEX "team1" |
Deletes vertices and the related incoming and outgoing edges of the vertices. |
UPDATE VERTEX | UPDATE VERTEX ON <tag_name> <vid> SET <update_prop> [WHEN <condition>] [YIELD <output>] |
UPDATE VERTEX ON player "player101" SET age = age + 2 |
Updates properties on tags of a vertex. |
UPSERT VERTEX | UPSERT VERTEX ON <tag> <vid> SET <update_prop> [WHEN <condition>] [YIELD <output>] |
UPSERT VERTEX ON player "player667" SET age = 31 |
The UPSERT statement is a combination of UPDATE and INSERT . You can use UPSERT VERTEX to update the properties of a vertex if it exists or insert a new vertex if it does not exist. |
Edge statements¶
Statement | Syntax | Example | Description |
---|---|---|---|
INSERT EDGE | INSERT EDGE [IF NOT EXISTS] <edge_type> ( <prop_name_list> ) {VALUES | VALUE} <src_vid> -> <dst_vid>[@<rank>] : ( <prop_value_list> ) [, <src_vid> -> <dst_vid>[@<rank>] : ( <prop_value_list> ), ...] |
INSERT EDGE e2 (name, age) VALUES "11"->"13":("n1", 1) |
Inserts an edge or multiple edges into a graph space from a source vertex (given by src_vid) to a destination vertex (given by dst_vid) with a specific rank in Nebula Graph. |
DELETE EDGE | DELETE EDGE <edge_type> <src_vid> -> <dst_vid>[@<rank>] [, <src_vid> -> <dst_vid>[@<rank>] ...] |
DELETE EDGE serve "player100" -> "team204"@0 |
Deletes one edge or multiple edges at a time. |
UPDATE EDGE | UPDATE EDGE ON <edge_type> <src_vid> -> <dst_vid> [@<rank>] SET <update_prop> [WHEN <condition>] [YIELD <output>] |
UPDATE EDGE ON serve "player100" -> "team204"@0 SET start_year = start_year + 1 |
Updates properties on an edge. |
UPSERT EDGE | UPSERT EDGE ON <edge_type> <src_vid> -> <dst_vid> [@rank] SET <update_prop> [WHEN <condition>] [YIELD <properties>] |
UPSERT EDGE on serve "player666" -> "team200"@0 SET end_year = 2021 |
The UPSERT statement is a combination of UPDATE and INSERT . You can use UPSERT EDGE to update the properties of an edge if it exists or insert a new edge if it does not exist. |
Index¶
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Native index
You can use native indexes together with
LOOKUP
andMATCH
statements.Statement Syntax Example Description CREATE INDEX CREATE {TAG | EDGE} INDEX [IF NOT EXISTS] <index_name> ON {<tag_name> | <edge_name>} ([<prop_name_list>]) [COMMENT = '<comment>']
CREATE TAG INDEX player_index on player()
Add native indexes for the existing tags, edge types, or properties. SHOW CREATE INDEX SHOW CREATE {TAG | EDGE} INDEX <index_name>
show create tag index index_2
Shows the statement used when creating a tag or an edge type. It contains detailed information about the index, such as its associated properties. SHOW INDEXES SHOW {TAG | EDGE} INDEXES
SHOW TAG INDEXES
Shows the defined tag or edge type indexes names in the current graph space. DESCRIBE INDEX DESCRIBE {TAG | EDGE} INDEX <index_name>
DESCRIBE TAG INDEX player_index_0
Gets the information about the index with a given name, including the property name (Field) and the property type (Type) of the index. REBUILD INDEX REBUILD {TAG | EDGE} INDEX [<index_name_list>]
REBUILD TAG INDEX single_person_index
Rebuilds the created tag or edge type index. If data is updated or inserted before the creation of the index, you must rebuild the indexes manually to make sure that the indexes contain the previously added data. SHOW INDEX STATUS SHOW {TAG | EDGE} INDEX STATUS
SHOW TAG INDEX STATUS
Returns the name of the created tag or edge type index and its status. DROP INDEX DROP {TAG | EDGE} INDEX [IF EXISTS] <index_name>
DROP TAG INDEX player_index_0
Removes an existing index from the current graph space.
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Syntax Example Description SIGN IN TEXT SERVICE [(<elastic_ip:port> [,<username>, <password>]), (<elastic_ip:port>), ...]
SIGN IN TEXT SERVICE (127.0.0.1:9200)
The full-text indexes is implemented based on Elasticsearch. After deploying an Elasticsearch cluster, you can use the SIGN IN
statement to log in to the Elasticsearch client.SHOW TEXT SEARCH CLIENTS
SHOW TEXT SEARCH CLIENTS
Shows text search clients. SIGN OUT TEXT SERVICE
SIGN OUT TEXT SERVICE
Signs out to the text search clients. CREATE FULLTEXT {TAG | EDGE} INDEX <index_name> ON {<tag_name> | <edge_name>} ([<prop_name_list>])
CREATE FULLTEXT TAG INDEX nebula_index_1 ON player(name)
Creates full-text indexes. SHOW FULLTEXT INDEXES
SHOW FULLTEXT INDEXES
Show full-text indexes. REBUILD FULLTEXT INDEX
REBUILD FULLTEXT INDEX
Rebuild full-text indexes. DROP FULLTEXT INDEX <index_name>
DROP FULLTEXT INDEX nebula_index_1
Drop full-text indexes. LOOKUP ON {<tag> | <edge_type>} WHERE <expression> [YIELD <return_list>]
LOOKUP ON player WHERE FUZZY(player.name, "Tim Dunncan", AUTO, OR) YIELD player.name
Use query options.
Subgraph and path statements¶
Type | Syntax | Example | Description |
---|---|---|---|
GET SUBGRAPH | GET SUBGRAPH [WITH PROP] [<step_count> STEPS] FROM {<vid>, <vid>...} [{IN | OUT | BOTH} <edge_type>, <edge_type>...] [YIELD [VERTICES AS <vertex_alias>] [,EDGES AS <edge_alias>]] |
GET SUBGRAPH 1 STEPS FROM "player100" YIELD VERTICES AS nodes, EDGES AS relationships |
Retrieves information of vertices and edges reachable from the source vertices of the specified edge types and returns information of the subgraph. |
FIND PATH | FIND { SHORTEST | ALL | NOLOOP } PATH [WITH PROP] FROM <vertex_id_list> TO <vertex_id_list><br/>OVER <edge_type_list> [REVERSELY | BIDIRECT] [<WHERE clause>] [UPTO <N> STEPS] [| ORDER BY $-.path] [| LIMIT <M>] |
FIND SHORTEST PATH FROM "player102" TO "team204" OVER * |
Finds the paths between the selected source vertices and destination vertices. A returned path is like (<vertex_id>)-[:<edge_type_name>@<rank>]->(<vertex_id) . |
Query tuning statements¶
Type | Syntax | Example | Description |
---|---|---|---|
EXPLAIN | EXPLAIN [format="row" | "dot"] <your_nGQL_statement> |
EXPLAIN format="row" SHOW TAGS EXPLAIN format="dot" SHOW TAGS |
Helps output the execution plan of an nGQL statement without executing the statement. |
PROFILE | PROFILE [format="row" | "dot"] <your_nGQL_statement> |
PROFILE format="row" SHOW TAGS EXPLAIN format="dot" SHOW TAGS |
Executes the statement, then outputs the execution plan as well as the execution profile. |
Operation and maintenance statements¶
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Syntax Description BALANCE DATA
Starts a task to balance the distribution of storage partitions in a Nebula Graph cluster or a Group. It returns the task ID ( balance_id
).BALANCE DATA <balance_id>
Shows the status of the BALANCE DATA
task.BALANCE DATA STOP
Stops the BALANCE DATA
task.BALANCE DATA REMOVE <host_list>
Scales in the Nebula Graph cluster and detaches specific storage hosts. BALANCE LEADER
Balances the distribution of storage raft leaders in a Nebula Graph cluster or a Group.
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Syntax Description SUBMIT JOB COMPACT
Triggers the long-term RocksDB compact
operation.SUBMIT JOB FLUSH
Writes the RocksDB memfile in the memory to the hard disk. SUBMIT JOB STATS
Starts a job that makes the statistics of the current graph space. Once this job succeeds, you can use the SHOW STATS
statement to list the statistics.SHOW JOB <job_id>
Shows the information about a specific job and all its tasks in the current graph space. The Meta Service parses a SUBMIT JOB
request into multiple tasks and assigns them to the nebula-storaged processes.SHOW JOBS
Lists all the unexpired jobs in the current graph space. STOP JOB
Stops jobs that are not finished in the current graph space. RECOVER JOB
Re-executes the failed jobs in the current graph space and returns the number of recovered jobs.
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Syntax Example Description KILL QUERY (session=<session_id>, plan=<plan_id>)
KILL QUERY(SESSION=1625553545984255,PLAN=163)
Terminates the query being executed, and is often used to terminate slow queries.
Last update: November 4, 2021