Postgresql函数卡在for循环中

select * from scm_main.fn_connection_stations(1219646)

打印消息“开始…”但不打印消息“…结束”.

CREATE OR REPLACE FUNCTION     
scm_main.fn_connection_stations(var_connection_id bigint)
RETURNS SETOF scm_main.typ_connection_stations AS
$BODY$DECLARE 
    var_affected                 INTEGER DEFAULT 0; 
    var_row                      scm_main.typ_connection_stations%ROWTYPE; 
BEGIN 
    RAISE NOTICE 'Start...'; 
    FOR var_row IN 
    SELECT DISTINCT v.vbvdata_station_id
    FROM scm_main.tbl_vbvdata AS v 
    INNER JOIN scm_main.tbl_packet AS p ON (v.vbvdata_packet_id = 
    p.packet_id and p.packet_connection_id = var_connection_id) 
    --WHERE v.vbvdata_packet_id IN 
    --( SELECT packet_id FROM scm_main.tbl_packet AS o_p WHERE 
    o_p.packet_connection_id = var_connection_id) 
    LOOP 
        RETURN NEXT var_row; 
    END LOOP; 
    RAISE NOTICE '...End'; 
    RETURN; 
END 
$BODY$
  LANGUAGE plpgsql STABLE STRICT
  COST 100
  ROWS 1000;
ALTER FUNCTION scm_main.fn_connection_stations(bigint)
  OWNER TO postgres;

查询本身非常简单,并在直接调用时运行,如下所示：

SELECT DISTINCT v.vbvdata_station_id 
FROM scm_main.tbl_vbvdata AS v 
INNER JOIN scm_main.tbl_packet AS p ON (v.vbvdata_packet_id =  
p.packet_id and p.packet_connection_id = 1219646)

我想问题必须是桌子的锁定.但我绝对不明白是什么原因以及可以解决的问题.

前段时间评论部分正在运作.但过了一会儿,出现了同样的问题.我通过更改查询并用内部联接替换条件(级联查询)来解决它.但这次他们都没有工作！

更新

我通过一个愚蠢的改变再次使它工作：

INNER JOIN scm_main.tbl_packet AS p ON (v.vbvdata_packet_id = p.packet_id 
  and p.packet_connection_id = var_connection_id)`

改为：

INNER JOIN scm_main.tbl_packet AS p ON (v.vbvdata_packet_id = p.packet_id)
  where p.packet_connection_id in (select var_connection_id)

并且工作得很好.

另一个有趣的观点是,即使是下面的更改也无法正常工作并仍然挂起：

INNER JOIN scm_main.tbl_packet AS p ON (v.vbvdata_packet_id = p.packet_id) 
  where p.packet_connection_id = var_connection_id

现在我找到了解决方案.但我想知道它是怎么发生的！