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我认为 agens-graph 是一个很好的图形数据库，我做了一些演示。但它不起作用。来人帮帮我？

Class.forName("net.bitnine.agensgraph.Driver");
        String connectionString = "jdbc:agensgraph://127.0.0.1:5433/agens";
        Properties properties = new Properties();
        properties.setProperty("username","agens");
        properties.setProperty("password","123456");
        properties.setProperty("graph_path","graphname");
        properties.setProperty("user","agens");
        Connection conn = DriverManager.getConnection(connectionString,properties);
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(
                "MATCH (n:person {name: 'Tom'})-[:knows]->(m:person) RETURN n.name AS n, m.name AS m;");
        while (rs.next()) {
            Vertex friend = (Vertex) rs.getObject(1);
            System.out.println(friend.getString("n"));
            System.out.println(friend.getInt("m"));
        }

安慰：

Exception in thread "main" org.postgresql.util.PSQLException: ERROR: graph_path is NULL

建议：使用 SET graph_path at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2477) at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2190) at org.postgresql.core。 v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:300) 在 org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:428) 在 org.postgresql.jdbc.PgStatement.execute(PgStatement.java:354) 在 org.postgresql .jdbc.PgStatement.executeWithFlags(PgStatement.java:301) 在 org.postgresql.jdbc.PgStatement.executeCachedSql(PgStatement.java:287) 在 org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:264) 在 org. postgresql.jdbc.PgStatement.executeQuery(PgStatement.java:231) 在 agensgraph 的 net.bitnine.agensgraph.jdbc.AgStatement.executeQuery(AgStatement.java:43)。AgensgraphTest.main(AgensgraphTest.java:18)

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1 回答 1

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您需要设置要在其上执行查询的图形：

ResultSet rs = stmt.executeQuery(
             "SET graph_path=mygraph;"+
             "MATCH (n:person {name: 'Tom'})-[:knows]->(m:person) RETURN n.name AS n, m.name AS m;"
);

其他可能性是为用户设置默认图形路径：

ALTER USER agens SET graph_path = 'mygraph';
于 2018-06-28T08:26:44.903 回答