希腊神话中的数据兽（Hugegraph--基于希腊神话人物关系数据的常用查询）

随着社交、电商、金融、零售、物联网等行业的快速发展，现实社会织起了了一张庞大而复杂的关系网，亟需一种支持海量复杂数据关系运算的数据库即图数据库。本系列文章是学习知识图谱以及图数据库相关的知识梳理与总结

本文会包含如下内容：

• 希腊神话人物关系数据
• Gremlin 常用语句汇总

本篇文章适合人群：架构师、技术专家、对知识图谱与图数据库感兴趣的高级工程师

通过Property Graph Model图数据模型来描述希腊神话中各人物角色的关系（也被成为人物关系图谱），具体关系详见下图

推荐使用HugeGraph-Studio 通过可视化的方式来执行上述代码。另外也可以通过HugeGraph-Client、HugeApi、GremlinConsole和GremlinDriver等多种方式执行下面的代码。（包括Schema、索引及数据的创建）

但注意如下：

• HugeGraph默认是自动生成Id，如果用户通过primaryKeys指定VertexLabel的primaryKeys字段列表后，VertexLabel的Id策略将会自动切换到primaryKeys策略。 启用primaryKeys策略后,HugeGraph通过vertexLabel primaryKeys拼接生成VertexId ，可实现自动去重，同时无需额外创建索引即可以使用primaryKeys中的属性进行快速查询。 例如 "character" 和 "location" 都有primaryKeys("name")属性，因此在不额外创建索引的情况下可以通过g.V().hasLabel('character') .has('name','hercules')查询vertex 。
• 针对character的age属性需要创建range索引，否则不能根据age进行范围过滤查询

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() schema.indexLabel("characterByAge").onV("character").by("age").range().ifNotExist().create(); // 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)