GO¶

GO [[<M> TO] <N> 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>,] <number_rows>];

<vertex_list> ::=
    <vid> [, <vid> ...]

<edge_type_list> ::=
   edge_type [, edge_type ...]
   | *

<return_list> ::=
    <col_name> [AS <col_alias>] [, <col_name> [AS <col_alias>] ...]

# The following example returns the teams that player 102 serves.
nebula> GO FROM "player102" OVER serve;
+------------+
| serve._dst |
+------------+
| "team203"  |
| "team204"  |
+------------+

# The following example returns the friends of player 102 with 2 hops.
nebula> GO 2 STEPS FROM "player102" OVER follow;
+-------------+
| follow._dst |
+-------------+
| "player101" |
| "player125" |
+-------------+
...

# The following example adds a filter for the traversal.
nebula> 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;

+-----------------+------------+---------------------+
| team_name       | start_year | player_name         |
+-----------------+------------+---------------------+
| "Spurs"         | 1997       | "Tim Duncan"        |
| "Trail Blazers" | 2006       | "LaMarcus Aldridge" |
| "Spurs"         | 2015       | "LaMarcus Aldridge" |
+-----------------+------------+---------------------+

# The following example traverses along with multiple edge types. If there is no value for a property, the output is UNKNOWN_PROP.
nebula> GO FROM "player100" OVER follow, serve \
        YIELD properties(edge).degree, properties(edge).start_year;
+-------------------------+-----------------------------+
| properties(EDGE).degree | properties(EDGE).start_year |
+-------------------------+-----------------------------+
| 95                      | UNKNOWN_PROP                |
| 95                      | UNKNOWN_PROP                |
| UNKNOWN_PROP            | 1997                        |
+-------------------------+-----------------------------+

# The following example returns the neighbor vertices in the incoming direction of player 100.
nebula> GO FROM "player100" OVER follow REVERSELY \
        YIELD src(edge) AS destination;
+-------------+
| destination |
+-------------+
| "player101" |
| "player102" |
+-------------+
...

# This MATCH query shares the same semantics with the preceding GO query.
nebula> MATCH (v)<-[e:follow]- (v2) WHERE id(v) == 'player100' \
        RETURN id(v2) AS destination;
+-------------+
| destination |
+-------------+
| "player101" |
| "player102" |
+-------------+
...

# The following example retrieves the friends of player 100 and the teams that they serve.
nebula> 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;
+---------------------+-----------------+
| FriendOf            | Team            |
+---------------------+-----------------+
| "Boris Diaw"        | "Spurs"         |
| "Boris Diaw"        | "Jazz"          |
| "Boris Diaw"        | "Suns"          |
...

# This MATCH query shares the same semantics with the preceding GO query.
nebula> MATCH (v)<-[e:follow]- (v2)-[e2:serve]->(v3)  \
        WHERE id(v) == 'player100' \
        RETURN v2.name AS FriendOf, v3.name AS Team;
+---------------------+-----------------+
| FriendOf            | Team            |
+---------------------+-----------------+
| "Boris Diaw"        | "Spurs"         |
| "Boris Diaw"        | "Jazz"          |
| "Boris Diaw"        | "Suns"          |
...

# The following example retrieves the friends of player 100 within 1 or 2 hops.
nebula> GO 1 TO 2 STEPS FROM "player100" OVER follow \
        YIELD dst(edge) AS destination;
+-------------+
| destination |
+-------------+
| "player101" |
| "player125" |
...

# This MATCH query shares the same semantics with the preceding GO query.
nebula> MATCH (v) -[e:follow*1..2]->(v2) \
        WHERE id(v) == "player100" \
        RETURN id(v2) AS destination;
+-------------+
| destination |
+-------------+
| "player100" |
| "player102" |
...

# The following example the outputs according to age.
nebula> 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;
+-------------+----------------------------+----------+
| dst         | src                        | age      |
+-------------+----------------------------+----------+
| "player125" | ["player101"]              | [41]     |
| "player100" | ["player125", "player101"] | [42, 42] |
| "player102" | ["player101"]              | [33]     |
+-------------+----------------------------+----------+

# The following example groups the outputs and restricts the number of rows of the outputs.
nebula> $a = GO FROM "player100" OVER follow YIELD src(edge) AS src, dst(edge) AS dst; \
        GO 2 STEPS FROM $a.dst OVER follow \
        YIELD $a.src AS src, $a.dst, src(edge), dst(edge) \
        | ORDER BY $-.src | OFFSET 1 LIMIT 2;
+-------------+-------------+-------------+-------------+
| src         | $a.dst      | follow._src | follow._dst |
+-------------+-------------+-------------+-------------+
| "player100" | "player125" | "player100" | "player101" |
| "player100" | "player101" | "player100" | "player125" |
+-------------+-------------+-------------+-------------+

# The following example determines if $$.player.name IS NOT EMPTY.
nebula> GO FROM "player100" OVER follow WHERE properties($$).name IS NOT EMPTY YIELD dst(edge);
+-------------+
| follow._dst |
+-------------+
| "player125" |
| "player101" |
+-------------+