Question

从两个sql语句中获取数据后，我插入了n行。到目前为止我使用了两种方法，第一种是Cursor，另一种是While循环。

嵌套光标：

    begin
    declare userId,taskId int default 0;
    declare userCnt int default 0;
    declare c1 cursor for select us_id from us_uxusermaster ;
    declare continue handler for not found set userCnt=1;
    open c1;
    CheckId: loop
    fetch c1 into userId;
    if userCnt=1
    then 
        leave CheckId;
    end if;
            Select pl.pl_minTarget into target from pl_planlist pl inner join ap_affiliateplan ap inner join us_uxusermaster us on Find_in_set(pl.pl_id,us.us_planListId) and ap.ap_id =us.us_taskPlanId where us_id=userId and pl.pl_serviceName=2;
                Begin
                DECLARE taskId int default 0;
                Declare taskCnt int default 0;
                Declare t1 cursor for select tk.tk_id  from tk_taskmaster tk where tk.tk_activeTime=AddDate(Current_date(),1)  and tk_actStatus=0 and tk_status=1 limit target;
                Declare continue handler for not found set taskCnt=1;
                open t1;
                CheckTask: loop
                fetch t1 into taskId;
                if taskCnt=1
                then
                leave CheckTask;
                end if;

                    insert into ut_userstask(ut_tk_id,ut_us_id,ut_edtm,ut_eby) values (taskId,userId,current_timestamp,'Via-Event');
                end loop checkTask;
                close t1;
                End;
    end loop CheckId;
    close c1;

    end;

While循环：

    begin
declare taskName,taskCode,description,url,userLevel,TaskStatus,TaskActStatus,Steps,taskId,userId varchar(50);

declare activationTime,deActivationTime datetime;

Declare flag,flag2,counts,counts2 int default 0; 
Drop Temporary Table if exists temptrigg;
Set @rownumber=0;
Set @rownumber2=0;
create temporary table  temptrigg as(select * from (select (@rownumber := @rownumber + 1) AS newrow, us_id from us_uxusermaster) AS xst);
select count(*) into counts from temptrigg;
while(flag<counts)
Do
Set flag=flag+1;
Select us_id into userId from temptrigg where newrow=flag;

Drop Temporary Table if exists temptrigg2;
Create temporary table temptrigg2 as(select * from(select (@rownumber2 := @rownumber2 + 1) as newrow2,tk.tk_id  from tk_taskmaster tk where tk.tk_activeTime=Current_date()  and tk_actStatus=0 and tk_status=1)as xst);
Select count(*) into Counts2 from temptrigg2;
While(flag2<Counts2)
Do
Set flag2=flag2+1;
Select tk_id into taskId from temptrigg2 where newrow2=flag2;

    insert into ut_userstask(ut_tk_id,ut_us_id,ut_edtm,ut_eby) values (taskId,userId,current_timestamp,'Via-Event');

End While;
End While;

end

这里的问题是while循环比光标花费的时间要长一倍。我对它的未来结果感到困惑。通过替换嵌套的while循环来跟踪游标是否合适。

插入425行光标时间为23.05秒，而循环时间为46秒。时间对我来说都太过分了。还有其他方法可以提高性能。

很高兴知道是否有。

Answer 1

我不确定我是否抓住了你在那里的所有支票（特别是limit），但如果你可以把它挤进一个插件中，它会节省很多..选择这样：

Insert into ut_userstask(ut_tk_id,ut_us_id,ut_edtm,ut_eby)
Select 
  tk.tk_id,
  us.us_id,
  current_timestamp,
  'Via-Event'
from pl_planlist pl 
inner join ap_affiliateplan ap 
inner join us_uxusermaster us on ap.ap_id = us.us_taskPlanId 
inner join tk_taskmaster tk on tk.tk_activeTime=AddDate(Current_date(),1) and tk_actStatus=0 and tk_status=1
where 
  pl.pl_serviceName=2
  and Find_in_set(pl.pl_id,us.us_planListId)

要记住的其他事项：确保您有正确的索引并尝试避免使用FIND_IN_SET之类的函数。这通常表明您的数据库没有足够的标准化，并且使用起来非常慢，因为它绕过了列上可用的任何索引。

即使你不能将everthing放在一个select中，循环主游标（例如获取用户）的速度可能更快，并为游标的每一行执行insert..select。

嵌套while循环比嵌套游标花费更多时间

1 个答案: