图数据库查询语言

本文介绍图数据库支持的gremlin和Cypher查询语言。

初始化数据

可使用gremlin api执行

gremlin api

POST http://localhost:8080/gremlin

{"gremlin":"这里是语句",
 "bindings": {},
"language": "gremlin-groovy",
"aliases": {
		"graph": "graphname", 
		"g": "__g_graphname"
	}
}

schema

schema = hugegraph.schema()

schema.propertyKey("name").asText().ifNotExist().create()
schema.propertyKey("age").asInt().ifNotExist().create()
schema.propertyKey("time").asInt().ifNotExist().create()
schema.propertyKey("reason").asText().ifNotExist().create()
schema.propertyKey("type").asText().ifNotExist().create()

schema.vertexLabel("character").properties("name", "age", "type").primaryKeys("name").nullableKeys("age").ifNotExist().create()
schema.vertexLabel("location").properties("name").primaryKeys("name").ifNotExist().create()

schema.edgeLabel("father").link("character", "character").ifNotExist().create()
schema.edgeLabel("mother").link("character", "character").ifNotExist().create()
schema.edgeLabel("battled").link("character", "character").properties("time").ifNotExist().create()
schema.edgeLabel("lives").link("character", "location").properties("reason").nullableKeys("reason").ifNotExist().create()
schema.edgeLabel("pet").link("character", "character").ifNotExist().create()
schema.edgeLabel("brother").link("character", "character").ifNotExist().create()

插入数据

// add vertices
Vertex saturn = graph.addVertex(T.label, "character", "name", "saturn", "age", 10000, "type", "titan")
Vertex sky = graph.addVertex(T.label, "location", "name", "sky")
Vertex sea = graph.addVertex(T.label, "location", "name", "sea")
Vertex jupiter = graph.addVertex(T.label, "character", "name", "jupiter", "age", 5000, "type", "god")
Vertex neptune = graph.addVertex(T.label, "character", "name", "neptune", "age", 4500, "type", "god")
Vertex hercules = graph.addVertex(T.label, "character", "name", "hercules", "age", 30, "type", "demigod")
Vertex alcmene = graph.addVertex(T.label, "character", "name", "alcmene", "age", 45, "type", "human")
Vertex pluto = graph.addVertex(T.label, "character", "name", "pluto", "age", 4000, "type", "god")
Vertex nemean = graph.addVertex(T.label, "character", "name", "nemean", "type", "monster")
Vertex hydra = graph.addVertex(T.label, "character", "name", "hydra", "type", "monster")
Vertex cerberus = graph.addVertex(T.label, "character", "name", "cerberus", "type", "monster")
Vertex tartarus = graph.addVertex(T.label, "location", "name", "tartarus")

// add edges
jupiter.addEdge("father", saturn)
jupiter.addEdge("lives", sky, "reason", "loves fresh breezes")
jupiter.addEdge("brother", neptune)
jupiter.addEdge("brother", pluto)
neptune.addEdge("lives", sea, "reason", "loves waves")
neptune.addEdge("brother", jupiter)
neptune.addEdge("brother", pluto)
hercules.addEdge("father", jupiter)
hercules.addEdge("mother", alcmene)
hercules.addEdge("battled", nemean, "time", 1)
hercules.addEdge("battled", hydra, "time", 2)
hercules.addEdge("battled", cerberus, "time", 12)
pluto.addEdge("brother", jupiter)
pluto.addEdge("brother", neptune)
pluto.addEdge("lives", tartarus, "reason", "no fear of death")
pluto.addEdge("pet", cerberus)
cerberus.addEdge("lives", tartarus)

创建索引

创建索引，使用REST API：

POST http://localhost:8080/graphs/hugegraph/schema/indexlabels

{
	"name": "characterAge",
	"base_type": "VERTEX_LABEL",
	"base_value": "character",
	"index_type": "RANGE",
	"fields": [
		"age"
	]
}

查询

API 说明

支持gremlin、sparql和Cypher api，推荐gremlin和Cypher

cypher api

http://127.0.0.1:8080/graphs/hugegraph/cypher?cypher=

eg:

curl http://127.0.0.1:8080/graphs/hugegraph/cypher?cypher=MATCH%20(n:character)-[:lives]-%3E(location)-[:lives]-(cohabitants)%20where%20n.name=%27pluto%27%20return%20cohabitants.name

gremlin api

POST http://localhost:8080/gremlin

{"gremlin":"这里是语句",
 "bindings": {},
"language": "gremlin-groovy",
"aliases": {
		"graph": "graphname", 
		"g": "__g_graphname"
	}
}

sparql api

GET http://127.0.0.1:8080/graphs/hugegraph/sparql?sparql=SELECT%20*%20WHERE%20{%20}

1. 查询hercules的祖父

g.V().hasLabel('character').has('name','hercules').out('father').out('father')

也可以通过repeat方式：

g.V().hasLabel('character').has('name','hercules').repeat(__.out('father')).times(2)

cypher

MATCH (n:character)-[:father]->()-[:father]->(grandfather) where n.name='hercules' return grandfather

2. Find the name of hercules's father

g.V().hasLabel('character').has('name','hercules').out('father').value('name')

cypher

MATCH (n:character)-[:father]->(father) where n.name='hercules' return father.name

3. Find the characters with age > 100

g.V().hasLabel('character').has('age',gt(100))

cypher

MATCH (n:character) where n.age > 10 return n

4. Find who are pluto's cohabitants

g.V().hasLabel('character').has('name','pluto').out('lives').in('lives').values('name')

cypher

MATCH (n:character)-[:lives]->(location)-[:lives]-(cohabitants) where n.name='pluto' return cohabitants.name

5. Find pluto can't be his own cohabitant

pluto = g.V().hasLabel('character').has('name', 'pluto')
g.V(pluto).out('lives').in('lives').where(is(neq(pluto)).values('name')

// use 'as'
g.V().hasLabel('character').has('name', 'pluto').as('x').out('lives').in('lives').where(neq('x')).values('name')

cypher> MATCH (src:character{name:"pluto"})-[:lives]->()<-[:lives]-(dst:character) RETURN dst.name

6. Pluto's Brothers

pluto = g.V().hasLabel('character').has('name', 'pluto').next()
// where do pluto's brothers live?
g.V(pluto).out('brother').out('lives').values('name')

// which brother lives in which place?
g.V(pluto).out('brother').as('god').out('lives').as('place').select('god','place')

// what is the name of the brother and the name of the place?
g.V(pluto).out('brother').as('god').out('lives').as('place').select('god','place').by('name')

MATCH (src:Character{name:"pluto"})-[:brother]->(bro:Character)-[:lives]->(dst)
RETURN bro.name, dst.name

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作者：Jadepeng
出处：jqpeng的技术记事本--http://www.cnblogs.com/xiaoqi
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