圖數據庫查詢語言

本文介紹圖數據庫支持的gremlin和Cypher查詢語言。

初始化數據

可使用gremlin api執行

gremlin api

POST http://localhost:8080/gremlin

{"gremlin":"這裏是語句",
 "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()

插入數據

// 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)

創建索引

創建索引，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"
	]
}

查詢

API 說明

支持gremlin、sparql和Cypher api，推薦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":"這裏是語句",
 "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. 查詢hercules的祖父

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

也可以通過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

---

作者：Jadepeng
出處：jqpeng的技術記事本--http://www.cnblogs.com/xiaoqi
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