错误:使用PostgreSQL 9.3在dblink中的函数需要列定义列表

Question

我有以下功能:

我通过使用加入其他数据库表来更新一个数据库表dblink().

我安装了:

create extension dblink;

更多细节如下图所示:

CREATE OR REPLACE FUNCTION Fun_test
(
    Table_Name varchar
) 
RETURNS void AS

$BODY$

DECLARE
    dynamic_statement varchar;

BEGIN
    perform dblink_connect('port=5234 dbname=testdb user=postgres password=****');


    dynamic_statement := 'With CTE AS 
    ( 
        Select HNumber,JoiningDate,Name,Address
        From '|| Table_Name ||'c 
    )
    , Test_A 
    AS 
    ( 
    Select Row_Number() over ( Partition by PNumber order by Date1 Desc,Date2 Desc) AS roNum,
    Name,PNumber,Date1,Address
    From dblink(
            ''Select distinct PNumber,
            (
                case when fname is null then '' else fname end || '' ||
                case when lname is null then '' else lname end 
            ) as FullName,
            Address,
            Date1,Date2
            From testdb_Table
            inner join CTE on CTE.HNumber = PNumber''
           )  Num 
    )
    Update CTE
    Set 
    Name = Test_A.FullName
    ,SubAddress_A = Test_A.Address
    ,Date1 = Test_A.Date1
    from CTE 
    left outer join Test_A on 
    CTE.HNumber= Test_A.PNumber 
    where roNum =1';

    RAISE INFO '%',dynamic_statement;

    EXECUTE dynamic_statement;

    perform dblink_disconnect();
END;

$BODY$

LANGUAGE PLPGSQL;   

调用功能:

select fun_test('test1');

得到错误:

ERROR:  a column definition list is required for functions returning "record"
LINE 11:    From dblink
                 ^

Answer 1

你必须告诉PostgreSQL dblink查询将返回的列是什么.

有关详细信息,请参阅dblink手册.

这与返回运行时确定record类型的任何函数相同.如果不告诉PostgreSQL结果的列布局是什么,你就无法查询它.

您使用列说明符列表,例如

SELECT * FROM my_function_returning_record() f(col1 text, col2 integer);

如果您使用的是当前的PostgreSQL版本,则可能需要将其postgres_fdw 视为替代版本dblink.