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  ;