Question

我在嵌入式graphDb

中的标签学生上创建了以下索引

Schema schema = graphDb.schema();    
indexDefinition = schema.indexFor(DynamicLabel.label("Student")).on("NodeType").create();
indexDefinition = schema.indexFor(DynamicLabel.label("Student")).on("Marks").create();

使用cypher MATCH 查询

这有效：match (n:Student) return n;

这也有效：match (n:Student) where n.Marks<30 return n;

但是，这失败了：match (n:Student) where n.Marks=30 return n;

这也是：match (n:Student) where n.Marks='30' return n;

好奇的是这个有用：

start n=node(127) match (n:Student) where n.Marks=30 return n;

工作：我得到了预期的结果，失败：没有结果

任何人都可以解释这种行为，因为所有属性都已经被索引（标签），并且密码应该返回所需的结果。

我还使用以下方法检查了标签的属性是否为索引：

Label label1 = DynamicLabel.label("Student");
System.out.println(schema.getIndexes(label1));

我正在使用this方法执行cypher查询。

[编辑]节点创建：

Integer marks = 30;
Label label = DynamicLabel.label("Student");
tx = graphDb.beginTx();
Node studentNode = graphDb.createNode(label);
studentNode.setProperty("NodeType", "Student");
studentNode.setProperty("Marks", marks);
tx.success();

Answer 1

这只是工作，请参阅以下代码段。你的剧本有什么不同？

final GraphDatabaseService graphDb = new GraphDatabaseFactory().newEmbeddedDatabase();
final ExecutionEngine cypher = new ExecutionEngine(graphDb);
try (Transaction tx = graphDb.beginTx()) {
    Schema schema = graphDb.schema();
    //schema.indexFor(DynamicLabel.label("Student")).on("NodeType").create();
    schema.indexFor(DynamicLabel.label("Student")).on("marks").create();
    Label label1 = DynamicLabel.label("Student");
    System.out.println(schema.getIndexes(label1));
    tx.success();
}
try (Transaction tx = graphDb.beginTx()) {
    Node node = graphDb.createNode(DynamicLabel.label("Student"));
    node.setProperty("marks", 20);
    node = graphDb.createNode(DynamicLabel.label("Student"));
    node.setProperty("marks", 30);
    node = graphDb.createNode(DynamicLabel.label("Student"));
    node.setProperty("marks", 40);
    System.out.println(cypher.execute("match (n:Student) return n").dumpToString());
            System.out.println(cypher.execute("match (n:Student) where n.marks<30 return n;").dumpToString());
    System.out.println(cypher.execute("match (n:Student) where n.marks=30 return n;").dumpToString());
    System.out.println(cypher.execute("match (n:Student) where n.marks='30' return n;").dumpToString());
    tx.success();
}

脚本输出：

[IndexDefinition[label:Student, on:marks]]
+-------------------+
| n                 |
+-------------------+
| Node[0]{marks:20} |
| Node[1]{marks:30} |
| Node[2]{marks:40} |
+-------------------+
3 rows

+-------------------+
| n                 |
+-------------------+
| Node[0]{marks:20} |
+-------------------+
1 row

+-------------------+
| n                 |
+-------------------+
| Node[1]{marks:30} |
+-------------------+
1 row

+---+
| n |
+---+
+---+
0 row

Neo4j cypher MATCH查询不起作用

1 个答案: