GET SUBGRAPH¶

The GET SUBGRAPH statement retrieves information of vertices and edges reachable from the start vertices over the specified types of edges.

Syntax¶

GET SUBGRAPH [<step_count> STEPS] FROM {<vid>, <vid>...}
[IN <edge_type>, <edge_type>...]
[OUT <edge_type>, <edge_type>...]
[BOTH <edge_type>, <edge_type>...]

Clause	Description
`STEPS`	Specifies the steps to go from the start vertices. A `step_count` must be a non-negative integer. Its default value is 1. When `<step_count>` is specified to `N`, the Nebula Graph returns zero to N steps subgraph.
`FROM`	Specifies the start vertices.
`IN`	Gets the subgraphs from the start vertices over the specified incoming edges (edges pointing to the start vertices).
`OUT`	Gets the subgraphs from the start vertices over the specified outgoing edges (edges pointing out from the start vertices).
`BOTH`	Gets the subgraphs from the start vertices over the specified types of edges, both incoming and outgoing.

When the traversal direction is not specified, both the incoming and outgoing edges are returned.

Examples¶

The following graph is used as the sample.

A sample graph for GET SUBGRAPH

Go one step from the vertex with VID "player100" over all types of edges and get the subgraph.

nebula> GET SUBGRAPH 1 STEPS FROM "player100";
+--------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------+
| _vertices                                                                                                                | _edges                                                                                                                                           |
+--------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------+
| [(player100) player.name:Tim,player.age:42]                                                                              | [player100-[follow]->player101@0 degree:96,player100-[follow]->player102@0 degree:90,player100-[serve]->team200@0 end_year:2016,start_year:1997] |
+--------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------+
| [(player101) player.age:36,player.name:Tony Parker,(player102) player.age:33,player.name:LaMarcus Aldridge,(team200) team.name:Warriors] | [player102-[follow]->player101@0 degree:75]                                                                                      |
+--------------------------------------------------------------------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------+
Got 2 rows (time spent 6289/7423 us)

The returned subgraph is as follows.

GET SUBGRAPH FROM "player100"

Go one step from the vertex with VID "player100" over incoming follow edges and get the subgraph.

nebula> GET SUBGRAPH 1 STEPS FROM "player100" IN follow;
+-----------+--------+
| _vertices | _edges |
+-----------+--------+
| []        | []     |
+-----------+--------+
| []        | []     |
+-----------+--------+
Got 2 rows (time spent 2292/3091 us)

There is no incoming follow edge to "player100", so no vertex or edge is returned.

Go one step from the vertex "player100" over outgoing serve edges and get the subgraph.

nebula> GET SUBGRAPH 1 STEPS FROM "player100" OUT serve;
+---------------------------------------------+--------------------------------------------------------------+
| _vertices                                   | _edges                                                       |
+---------------------------------------------+--------------------------------------------------------------+
| [(player100) player.age:42,player.name:Tim] | [player100-[serve]->team200@0 start_year:1997,end_year:2016] |
+---------------------------------------------+--------------------------------------------------------------+
| [(team200) team.name:Warriors]              | []                                                           |
+---------------------------------------------+--------------------------------------------------------------+
Got 2 rows (time spent 2107/2547 us)

The returned subgraph is as follows.

GET SUBGRAPH FROM "100" OUT serve

Last update: April 15, 2021