Titan db如何列出所有图索引

Question

我一直在研究管理系统，但有些事情仍然让我难以理解。基本上我想做的是：

• 列出所有基于边缘的索引（包括以顶点为中心）。
• 列出所有基于顶点的索引（如果索引附加到标签，则基于每个标签）。

这基本上就像绘制图形模式。

我已经尝试了一些方法，但我最多只能获得部分数据。

g.getIndexdKeys(<Vertex or Edge>); 
//basic information. Doesn't seem to return any buildEdgeIndex() based indexes

mgmt.getVertexLabels(); 
// gets labels, can't find a way of getting indexes attached to these labels.

mgmt.getGraphIndexes(Vertex.class); 
// works nicely I can retrieve Vertex indexes and get pretty much any 
// information I want out of them except for information regarding 
// indexOnly(label). So I can't tell what label these indexes are attached to.

mgmt.getGraphIndexes(Edge.class); 
// doesn't seem to return any buildEdgeIndex() indexes.

任何填补空白的帮助都会有所帮助。

我想知道：

• 如何通过 indexOnly() 找到附加到标签（或附加到索引的标签）的索引
• 如何列出通过 buildEdgeIndex() 设置的边缘索引及其各自的边缘标签？

提前致谢。

额外信息： Titan 0.5.0，Cassandra 后端，来自 rexster。

Answer 1

这不是很直接，因此我将使用一个示例来展示它。

让我们从众神图 + 一个额外的神名索引开始：

g = TitanFactory.open("conf/titan-cassandra-es.properties")
GraphOfTheGodsFactory.load(g)
m = g.getManagementSystem()
name = m.getPropertyKey("name")
god = m.getVertexLabel("god")
m.buildIndex("god-name", Vertex.class).addKey(name).unique().indexOnly(god).buildCompositeIndex()
m.commit()

现在让我们再次拉出索引信息。

gremlin> m = g.getManagementSystem()
==>com.thinkaurelius.titan.graphdb.database.management.ManagementSystem@2f414e82

gremlin> // get the index by its name
gremlin> index = m.getGraphIndex("god-name")
==>com.thinkaurelius.titan.graphdb.database.management.TitanGraphIndexWrapper@e4f5395

gremlin> // determine which properties are covered by this index
gremlin> gn.getFieldKeys()
==>name

//
// the following part shows what you're looking for
//
gremlin> import static com.thinkaurelius.titan.graphdb.types.TypeDefinitionCategory.*

gremlin> // get the schema vertex for the index
gremlin> sv = m.getSchemaVertex(index)
==>god-name

gremlin> // get index constraints
gremlin> rel = sv.getRelated(INDEX_SCHEMA_CONSTRAINT, Direction.OUT)
==>com.thinkaurelius.titan.graphdb.types.SchemaSource$Entry@5162bf3

gremlin> // get the first constraint; no need to do a .hasNext() check in this
gremlin> // example, since we know that we will only get a single entry
gremlin> sse = rel.iterator().next()
==>com.thinkaurelius.titan.graphdb.types.SchemaSource$Entry@5162bf3

gremlin> // finally get the schema type (that's the vertex label that's used in .indexOnly())
gremlin> sse.getSchemaType()
==>god

干杯， 丹尼尔