非易失性函数postgres中不允许更新

Question

我尝试使用带有多个参数的游标，函数创建没有任何问题，但是当我使用

调用我的函数时

select scratchpad.update_status()

我收到以下错误：

update is not allowed in a non volatile function

函数：

create  function scrat.update_status() returns void
as
$$
DECLARE
  day_to_process record;

BEGIN
FOR  day_to_process   in  (SELECT distinct inst_status.date,inst_status.code,scrat.inst_status.id
                             FROM scrat.inst_status
                             WHERE inst_status.status ='S'
                             ORDER BY 1)
  LOOP
    raise notice 'Processing Date %', day_to_process.date::text;
   update scrat.inst_status
    set status = (select a.status from
                                  (select status, max(date)
                                FROM scrat.inst_status
                                where status <> 'S'
                                  and date::date < day_to_process.date
                                group by status
                                order by 2 desc
                                limit 1)a)
    where inst_status.date = day_to_process.date
      and id =day_to_process.id
      and code=day_to_process.code;
  END LOOP;
END ;
$$ LANGUAGE plpgsql STABLE;

Answer 1

如the documentation所述：

STABLE indicates that the function cannot modify the database, and that within a single table scan it will consistently return the same result for the same argument values, but that its result could change across SQL statements.

因此您必须将函数标记为 VOLATILE。

非易失性函数postgres中不允许更新

update is not allowed in a non volatile function postgres

postgresql

function

cursor