FETCH Syntax¶
The FETCH syntax is used to get vertex/edge's properties.
Fetch Vertex Properties¶
Use FETCH PROP ON to return a (list of) vertex's properties. Currently, you can get multiple vertices' properties with the same tag in one statement. You can use FETCH together with pipe and user defined variables.
FETCH PROP ON {<tag_name> | <tag_name_list> | *} <vertex_id_list> [YIELD [DISTINCT] <return_list>]
Fetch <tag_name_list> is only available for version 1.2.1 or later version. If your Nebula Graph is earlier than 1.2.1, you can only fetch one type of vertices in a single query.
* indicates returning all the properties of the given vertex.
<tag_name_list>::=[tag_name [, tag_name]] is the tag name. It must be the same tag within return_list.
<vertex_id_list>::=[vertex_id [, vertex_id]] is a list of vertex IDs separated by comma (,).
[YIELD [DISTINCT] <return_list>] is the property list returned. Please refer YIELD Syntax for usage.
Examples¶
-- return all the properties of vertex 100.
nebula> FETCH PROP ON * 100;
-- return all the properties on tag player and team of vertex 100, 102
nebula> FETCH PROP ON * 100, 102;
-- return all properties of vertex 100, 201。
nebula> FETCH PROP ON player, team 100, 201;
-- return all the properties in tag player of vertex id 100 if no yield field is given.
nebula> FETCH PROP ON player 100;
-- return property name and age of vertex id 100.
nebula> FETCH PROP ON player 100 YIELD player.name, player.age;
-- hash string to int64 as vertex id, fetch name and player.
nebula> FETCH PROP ON player hash("nebula") YIELD player.name, player.age;
-- you can use fetch with pipe.
nebula> YIELD 100 AS id | FETCH PROP ON player $-.id;
-- find all neighbors of vertex 100 through edge follow. Then get the neighbors' name and age.
nebula> GO FROM 100 OVER follow YIELD follow._dst AS id | FETCH PROP ON player $-.id YIELD player.name, player.age;
-- the same as above statement.
nebula> $var = GO FROM 100 OVER follow YIELD follow._dst AS id; FETCH PROP ON player $var.id YIELD player.name, player.age;
-- get three vertices 100, 101, 102 and return by unique(distinct) name and age.
nebula> FETCH PROP ON player 100,101,102 YIELD DISTINCT player.name, player.age;
Fetch Edge Property¶
The FETCH usage of an edge is almost the same with vertex.
You can get properties from multiple edges with the same type.
FETCH PROP ON <edge_type> <vid> -> <vid>[@<rank>] [, <vid> -> <vid> ...] [YIELD [DISTINCT] <return_list>]
<edge_type> specifies the edge's type. It must be the same as those in <return_list>.
<vid> -> <vid> denotes a starting vertex to (->) an ending vertex. Multiple edges are separated by comma(,).
<rank> specifies the edge rank of the same edge type; it's optional. If not specified, the edge ranked 0 is returned by default.
[YIELD [DISTINCT] <return_list>] is the property list returned.
Example¶
-- from vertex 100 to 200 with edge type serve, get all the properties since no YIELD is given.
nebula> FETCH PROP ON serve 100 -> 200;
-- only return property start_year.
nebula> FETCH PROP ON serve 100 -> 200 YIELD serve.start_year;
-- for all the out going edges of vertex 100, get edge property degree.
nebula> GO FROM 100 OVER follow YIELD follow.degree;
-- the same as above statement.
nebula> GO FROM 100 OVER follow YIELD follow._src AS s, follow._dst AS d \
| FETCH PROP ON follow $-.s -> $-.d YIELD follow.degree;
-- the same as above.
nebula> $var = GO FROM 100 OVER follow YIELD follow._src AS s, follow._dst AS d;\
FETCH PROP ON follow $var.s -> $var.d YIELD follow.degree;