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，7-2-4-7delete 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 ngroup by n.nodeorder 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) rorder by r.up_node	;