nGQL cheatsheet

Functions

• Math functions

  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)	Returns 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 as max and min is 0 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 as max and min is 0 by default. If you set no argument, the system returns a random signed 64-bit integer.
  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 or the length of a string.
  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) returns 3.141592653589793.

• Aggregating functions

  Function	Description
  avg()	Returns the average value of the argument.
  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.
  max()	Returns the maximum value.
  min()	Returns the minimum value.
  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.
  std()	Returns the population standard deviation.
  sum()	Returns the sum value.

• String functions

  Function	Description
  int strcasecmp(string a, string b)	Compares string a and b without case sensitivity. When a = b, the return
  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(a)	Returns the length of the given string in bytes or the length of a path in hops.
  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 right(string a, int count)	Returns a substring consisting of count characters from the right side of
  string lpad(string a, int size, string letters)	Left-pads string a with string letters and returns a
  string rpad(string a, int size, string letters)	Right-pads string a with string letters and returns a
  string substr(string a, int pos, int count)	Returns a substring extracting count characters starting from
  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.
  concat()	The concat() function requires at least two or more strings. All the parameters are concatenated into one string. Syntax: concat(string1,string2,...)
  concat_ws()	The concat_ws() function connects two or more strings with a predefined separator.
  extract()	extract() uses regular expression matching to retrieve a single substring or all substrings from a string.
  json_extract()	The json_extract() function converts the specified JSON string to map.

• Data and time functions

  Function	Description
  int now()	Returns the current timestamp of the system.
  timestamp timestamp()	Returns the current timestamp of the system.
  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.

• Schema-related functions

  • For nGQL statements

    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.
    vertex	Returns the information of vertices, including VIDs, tags, properties, and values.
    edge	Returns the information of edges, including edge types, source vertices, destination vertices, ranks, properties, and values.
    vertices	Returns the information of vertices in a subgraph. For more information, see GET SUBGRAPH.
    edges	Returns the information of edges in a subgraph. For more information, see GET SUBGRAPH.
    path	Returns the information of a path. For more information, see FIND PATH.

  • For statements compatible with openCypher

    Function	Description
    id(<vertex\>)	Returns the ID of a vertex. The data type of the result is the same as the vertex ID.
    list tags(<vertex\>)	Returns the Tag of a vertex, which serves the same purpose as labels().
    list labels(<vertex\>)	Returns the Tag of a vertex, which serves the same purpose as tags(). This function is used for compatibility with openCypher syntax.
    map properties(<vertex_or_edge\>)	Returns the properties of a vertex or 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.
    vertex startNode(<path\>)	Visits an edge or a path and returns its source vertex ID.
    string endNode(<path\>)	Visits an edge or a path and returns its destination vertex ID.
    int rank(<edge\>)	Returns the rank value of an edge.

• List functions

  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.
  reduce()	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.

• Type conversion functions

  Function	Description
  bool toBoolean()	Converts a string value to a boolean value.
  float toFloat()	Converts an integer or string value to a floating point number.
  string toString()	Converts non-compound types of data, such as numbers, booleans, and so on, to strings.
  int toInteger()	Converts a floating point or string value to an integer value.
  set toSet()	Converts a list or set value to a set value.
  int 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.

• Predicate functions

  Predicate functions return true or false. They are most commonly used in WHERE clauses.

  <predicate>(<variable> IN <list> WHERE <condition>)

  Function	Description
  exists()	Returns true if the specified property exists in the vertex, edge or map. Otherwise, returns false.
  any()	Returns true if the specified predicate holds for at least one element in the given list. Otherwise, returns false.
  all()	Returns true if the specified predicate holds for all elements in the given list. Otherwise, returns false.
  none()	Returns true if the specified predicate holds for no element in the given list. Otherwise, returns false.
  single()	Returns true if the specified predicate holds for exactly one of the elements in the given list. Otherwise, returns false.

• Conditional expressions functions

  Function	Description
  CASE	The CASE expression uses conditions to filter the result of an nGQL query statement. It is usually used in the YIELD and RETURN clauses. The CASE expression will traverse all the conditions. When the first condition is met, the CASE expression stops reading the conditions and returns the result. If no conditions are met, it returns the result in the ELSE clause. If there is no ELSE clause and no conditions are met, it returns NULL.
  coalesce()	Returns the first not null value in all expressions.

General queries statements

• MATCH

  MATCH <pattern> [<clause_1>] RETURN <output> [<clause_2>];

  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 multiple tags	MATCH (v:player:team) RETURN v	To match vertices with multiple tags, use colons (:).
  Match vertex properties	MATCH (v:player{name:"Tim Duncan"}) RETURN v MATCH (v) WITH v, properties(v) as props, keys(properties(v)) as kk WHERE [i in kk where props[i] == "Tim Duncan"] RETURN v	You can specify a vertex property with {<prop_name>: <prop_value>} after the tag in a pattern; or use a vertex property value to get vertices directly.
  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.player.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 MATCH ()<-[e]-() 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 MATCH ()-[e]->() WITH e, properties(e) as props, keys(properties(e)) as kk WHERE [i in kk where props[i] == 90] RETURN e	You can specify edge type properties with {<prop_name>: <prop_value>} in a pattern. For example: [e:follow{likeness:95}]; or use an edge type property value to get edges directly.
  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. The data type of e is the list.
  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. minHop and maxHop are optional and the default value is 1 and infinity respectively. The data type of e is the list.
  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, and maxHop take effect on all edge types. The data type of e is the list.
  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 the labels(v) list, use labels(v)[n-1].
  Retrieve a single property on a vertex or an edge	MATCH (v:player{name:"Tim Duncan"}) RETURN v.player.age	Use RETURN {<vertex_name> | <edge_name>}.<property> to retrieve a single property. Use AS 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.

• OPTIONAL MATCH

  Pattern	Example	Description
  Matches patterns against your graph database, just like MATCH does.	MATCH (m)-[]->(n) WHERE id(m)=="player100" OPTIONAL MATCH (n)-[]->(l) RETURN id(m),id(n),id(l)	If no matches are found, OPTIONAL MATCH will use a null for missing parts of the pattern.

• LOOKUP

  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 is Tony Parker and the tag is player.
  Retrieve edges	LOOKUP ON follow WHERE follow.degree == 90 YIELD follow.degree	Returns edges whose degree is 90 and the edge type is follow.
  List vertices with a tag	LOOKUP ON player YIELD properties(vertex),id(vertex)	Shows how to retrieve the VID of all vertices tagged with player.
  List edges with an edge types	LOOKUP ON follow YIELD edge AS e	Shows how to retrieve the source Vertex IDs, destination vertex IDs, and ranks of all edges of the follow edge type.
  Count the numbers of vertices or edges	`LOOKUP ON player YIELD id(vertex)	YIELD COUNT(*) AS Player_Count`
  Count the numbers of edges	`LOOKUP ON follow YIELD edge as e	YIELD COUNT(*) AS Like_Count`

• GO

  GO [[<M> TO] <N> {STEP|STEPS} ] FROM <vertex_list>
  OVER <edge_type_list> [{REVERSELY | BIDIRECT}]
  [ WHERE <conditions> ]
  YIELD [DISTINCT] <return_list>
  [{SAMPLE <sample_list> | LIMIT <limit_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 YIELD dst(edge)	Returns the teams that player 102 serves.
  GO 2 STEPS FROM "player102" OVER follow YIELD dst(edge)	Returns the friends of player 102 with 2 hops.
  GO FROM "player100", "player102" OVER serve WHERE properties(edge).start_year > 1995 YIELD DISTINCT properties($$).name AS team_name, properties(edge).start_year AS start_year, properties($^).name AS player_name	Adds a filter for the traversal.
  GO FROM "player100" OVER follow, serve YIELD properties(edge).degree, properties(edge).start_year	The following example traverses along with multiple edge types. If there is no value for a property, the output is NULL.
  GO FROM "player100" OVER follow REVERSELY YIELD src(edge) AS destination	The following example returns the neighbor vertices in the incoming direction of player 100.
  `GO FROM "player100" OVER follow REVERSELY YIELD src(edge) AS id	GO FROM $-.id OVER serve WHERE properties($^).age > 20 YIELD properties($^).name AS FriendOf, properties($$).name AS Team`
  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`

• FETCH

  • Fetch vertex properties

    FETCH PROP ON {<tag_name>[, tag_name ...] | *} 
    <vid> [, vid ...] 
    YIELD <return_list> [AS <alias>]

    Example	Description
    FETCH PROP ON player "player100" YIELD properties(vertex)	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" YIELD properties(vertex)	Specify multiple VIDs (vertex IDs) to fetch properties of multiple vertices. Separate the VIDs with commas.
    FETCH PROP ON player, t1 "player100", "player103" YIELD properties(vertex)	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" YIELD properties(vertex)	Set an asterisk symbol * to fetch properties by all tags in the current graph space.

  • Fetch edge properties

    FETCH PROP ON <edge_type> <src_vid> -> <dst_vid>[@<rank>] [, <src_vid> -> <dst_vid> ...]
    YIELD <output>;

    Example	Description
    FETCH PROP ON serve "player100" -> "team204" YIELD properties(edge)	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" YIELD properties(edge)	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 YIELD properties(edge)	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`
    $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.

• 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 NebulaGraph.
  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 NebulaGraph.
  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
  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 $$.player.name as Name	GROUP BY $-.Name YIELD$-.Name as Player, count(*) AS Name_Count`
LIMIT	YIELD <var> [| LIMIT [<offset_value>,] <number_rows>]	`GO FROM "player100" OVER follow REVERSELY YIELD $.player.name AS Friend,$.player.age AS Age	ORDER BY $-.Age,$-.Friend
SKIP	RETURN <var> [SKIP <offset>] [LIMIT <number_rows>]	MATCH (v:player{name:"Tim Duncan"}) --> (v2) RETURN v2.player.name AS Name, v2.player.age AS Age ORDER BY Age DESC SKIP 1	SKIP can be used alone to set the offset and return the data after the specified position.
SAMPLE	<go_statement> SAMPLE <sample_list>;	GO 3 STEPS FROM "player100" OVER * YIELD properties($$).name AS NAME, properties($$).age AS Age SAMPLE [1,2,3];	Takes samples evenly in the result set and returns the specified amount of data.
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`
RETURN	RETURN {<vertex_name>|<edge_name>|<vertex_name>.<property>|<edge_name>.<property>|...}	MATCH (v:player) RETURN v.player.name, v.player.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.player.name == "Tim Duncan" XOR (v.player.age < 30 AND v.player.name == "Yao Ming") OR NOT (v.player.name == "Yao Ming" OR v.player.name == "Tim Duncan") RETURN v.player.name, v.player.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
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.
UNWIND	UNWIND <list> AS <alias> <RETURN clause>	UNWIND [1,2,3] AS n RETURN n	Splits a list into rows.

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 NebulaGraph examples.
DESCRIBE SPACE	DESC[RIBE] SPACE <graph_space_name>	DESCRIBE SPACE basketballplayer	Returns the information about the specified graph space.
CLEAR SPACE	CLEAR SPACE [IF EXISTS] <graph_space_name>	Deletes the vertices and edges in a graph space, but does not delete the graph space itself and the schema information.
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>	DROP TAG test;	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 (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.
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_props, [tag_props] ...] VALUES <vid>: ([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 NebulaGraph.
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 <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 NebulaGraph.
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

• Native index

  You can use native indexes together with LOOKUP and MATCH 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.

• Full-text index

  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> [,<prop_name>]...) [ANALYZER="<analyzer_name>"]	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 ES_QUERY(<index_name>, "<text>") YIELD <return_list> [| LIMIT [<offset>,] <number_rows>]	LOOKUP ON player WHERE ES_QUERY(fulltext_index_1,"Chris") YIELD id(vertex)	Use query options.

Subgraph and path statements

Type	Syntax	Example	Description
GET SUBGRAPH	GET SUBGRAPH [WITH PROP] [<step_count> {STEP|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> OVER <edge_type_list> [REVERSELY | BIDIRECT] [<WHERE clause>] [UPTO <N> {STEP|STEPS}] YIELD path as <alias> [| ORDER BY $-.path] [| LIMIT <M>]	FIND SHORTEST PATH FROM "player102" TO "team204" OVER * YIELD path as p	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 PROFILE format="dot" SHOW TAGS	Executes the statement, then outputs the execution plan as well as the execution profile.

Operation and maintenance statements

• SUBMIT JOB BALANCE

  Syntax	Description
  BALANCE LEADER	Starts a job to balance the distribution of all the storage leaders in graph spaces. It returns the job ID.

• Job statements

  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.

• Kill queries

  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.

• Kill sessions

  Syntax	Example	Description
  KILL {SESSION|SESSIONS} <SessionId>	KILL SESSION 1672887983842984	Terminates a single session.
  SHOW SESSIONS | YIELD $-.SessionId AS sid [WHERE <filter_clause>] | KILL {SESSION|SESSIONS} $-.sid	`SHOW SESSIONS	YIELD $-.SessionId AS sid,$-.CreateTime as CreateTime
  `SHOW SESSIONS	KILL SESSIONS $-.SessionId`	`SHOW SESSIONS