PostgreSQL图(graph）的递归查询实例

-- 每一条有向关系边都存在上游，下游两个节点
drop table if exists demo.t_rel;
create table if not exists demo.t_rel(up int , down int);

-- 唯一约束，避免插入相同的关系
alter table demo.t_rel add constraint udx_t_rel unique (up, down);

insert into demo.t_rel values(6,5),(3,7),(5,1),(1,2),(5,2),(5,7),(7,2),(2,4),(7,4);

-- 构造一条环数据，7-2-4-7
delete from demo.t_rel where up=4 and down=7;
insert into demo.t_rel values(4,7);

with recursive 
downstream as
(
	select 1 as lvl, r.up, r.down, 
			-- 保存当前路径
			array[]::int[] || r.up || r.down as trace 
		from demo.t_rel r  
	where r.up = 7 -- 指定起点
	union all
	select ds.lvl +1, r.up, r.down, ds.trace || r.down
		from demo.t_rel r , downstream ds 
	where r.up = ds.down
		-- 破环
		and not r.down = any(ds.trace)
		and ds.lvl < 20 -- 最大深度
)
select * from downstream ds;

-- 可以看到并没有包括7-2-4-7这条环。
 lvl | up | down | trace
-----+----+------+---------
 1 | 7 | 2 | {7,2}
 1 | 7 | 4 | {7,4}
 2 | 2 | 4 | {7,2,4}
(3 rows)

drop function if exists f_get_rel;

/*
取得某个节点的相关联节点，和路径信息。
@start_node 起始节点。
@direct_flag 查询方向，-1：查找上级；1：查找下级； 0：查找上下级；
@max_depth 递归深度，即查找最多几级关系。
*/
create or replace function f_get_rel(start_node int, direct_flag int=1, max_depth int=20) 
	returns table (direct int, cur_depth int, up_node int, down_node int, trace int[])
as $$
begin

	return query 
		with recursive 
		downstream as
		(
			select 1 as lvl, r.up, r.down, array[]::int[] || r.up || r.down as trace 
				from demo.t_rel r 
			where r.up = start_node
				and direct_flag in (0, 1)
			union all
			select ds.lvl +1, r.up, r.down, ds.trace || r.down
				from demo.t_rel r , downstream ds 
			where r.up = ds.down
				and not r.down = any(ds.trace)
				and ds.lvl < max_depth
		),
		upstream as
		(
			select 1 as lvl, r.up, r.down, array[]::int[] || r.up || r.down as trace 
				from demo.t_rel r 
			where r.down = start_node
				and direct_flag in (0, -1)
			union all
			select us.lvl +1, r.up, r.down, r.up || us.trace 
				from demo.t_rel r , upstream us 
			where r.down = us.up
				and not r.up = any(us.trace)
				and us.lvl < max_depth
		)
		select -1, us.* from upstream us 
			union all 
		select 1, ds.* from downstream ds
		order by 1 desc, lvl, up, down
	;

end;
$$ language plpgsql strict;

dap=# select * from demo.f_get_rel(7,0,3);
 direct | cur_depth | up_node | down_node | trace
--------+-----------+---------+-----------+-----------
  1 |   1 |  7 |   2 | {7,2}
  1 |   1 |  7 |   4 | {7,4}
  1 |   2 |  2 |   4 | {7,2,4}
  -1 |   1 |  3 |   7 | {3,7}
  -1 |   1 |  4 |   7 | {4,7}
  -1 |   1 |  5 |   7 | {5,7}
  -1 |   2 |  2 |   4 | {2,4,7}
  -1 |   2 |  6 |   5 | {6,5,7}
  -1 |   3 |  1 |   2 | {1,2,4,7}
  -1 |   3 |  5 |   2 | {5,2,4,7}
(10 rows)

option = {
 title: {
  text: '数据图谱'
 },
 tooltip: {},
 animationDurationUpdate: 1500,
 animationEasingUpdate: 'quinticInOut',
 series : [
  {
   type: 'graph',
   layout: 'force',
   force: {
     repulsion: 1000
    },
   focusNodeAdjacency: true,
   symbolSize: 30,
   roam: true,
   label: {
    normal: {
     show: true
    }
   },
   edgeSymbol: ['circle', 'arrow'],
   edgeSymbolSize: [4, 10],
   edgeLabel: {
    normal: {
     textStyle: {
      fontSize: 20
     }
    }
   },
   data: [
    { name:"2", draggable: true, symbolSize:20},
   ],
   links: [
    { source:"2", target:"4"},
   ],

  }
 ]
};

-- 根据节点的关联点数量，设置图形大小
with rel as (select * from f_get_rel(7,0,2)),
	up_nodes as (select up_node, count(distinct down_node) as out_cnt from rel group by up_node),
	down_nodes as (select down_node, count(distinct up_node) as in_cnt from rel group by down_node),
	node_cnt as ( select up_node as node, out_cnt as cnt from up_nodes union all select * from down_nodes )
select '{ name:"' || n.node || '", draggable: true, symbolSize:' || sum(n.cnt) * 10 || '},' as node
	from node_cnt n
group by n.node
order by 1;

select distinct r.up_node, r.down_node, '{ source:"'|| r.up_node ||'", target:"'|| r.down_node ||'"},' as links 
	from f_get_rel(7,0,3) r
order by r.up_node	;