PL/SQL Proc性能调整

Question

我在 proc 中有一个循环，它循环通过一个 ID。 CDID 可以有 4 种类型：

CDID      TYPE
123     AA
456     BB
789     CC
999     DD

每种类型有4个主要的IF块。尽管 CDID 没有必要拥有所有 4 种类型，并且每个主 IF 块都由嵌套的 if 块组成。在嵌套的 ifs 中，我使用 select 查询将值插入 4 个变量（不是 table）。在所有 4 个 IF 块的末尾，有一个更新语句获取 4 个变量的值并更新 table.

下面是proc结构供大家参考：

CREATE OR REPLACE PROC MY_PROC
a varchar2;
b varchar2;
c varchar2;
d varchar2;
v_cnt number
BEGIN
FOR I IN (SELECT CDID FROM TABLE_A where column is null)    --this table contains only 1 row for each id
BEGIN
    select count(*) into v_cnt from TABLE_B where cdid=i.cdid and type='AA';
    if v_count > 0 then
        nested ifs
        SELECT a,b,c,d INTO a,b,c,d from TABLE_B where cdid=i.cdid and type='AA'...;
        end ifs...;

    if v_count = 0 then --if count is zero of TYPE:AA

    select count(*) into v_cnt from TABLE_B where cdid=i.cdid and type='BB';  
    if v_count > 0 then
       nested ifs
       select a,b,c,d INTO a,b,c,d from TABLE_B where cdid=i.cdid and type='BB'...;
       end ifs...;

    if v_count = 0 then --if count is zero of TYPE:BB
        same thing continues for TYPES CC AND DD.
    end if;
END;
UPDATE TABLE_A
SET COLUMN1=A,
    COLUMN2=B,
    COLUMN3=C,
    COLUMN4=D
where cdid=i.cdid;
END LOOP;
END;

大约。 30k-35k 记录，proc 需要 40 分钟来执行。在上面的过程中，对于每个cdid，它可以检查多个if.

我无法确定如何微调此过程。如何批量处理记录？

Answer 1

未经测试，但根据@GloezTrol 在评论中所说的内容，类似下面的内容应该有效。使用按类型排序的单个游标，以便它以正确的顺序处理 IF。然后循环直到找到你想要的记录退出。

CREATE OR REPLACE PROC MY_PROC as
a varchar2(10); -- size these appropriately
b varchar2(10);
c varchar2(10);
d varchar2(10);
v_cnt number;

cursor loop_cur is
select *
from TABLE_B 
where cdid=i.cdid
and type in ('AA','BB','CC','DD')
order by type asc;

BEGIN
  FOR I IN (SELECT CDID FROM TABLE_A where column is null)    --this table contains only 1 row for each id
    BEGIN
      -- good practice to re-initialize variables at start of loop
      a := null;
      b := null;
      c := null;
      d := null;

      for v_row in loop_cur loop
        if v_row.type = 'AA' then
          nested ifs
            a := v_row.a;
            b := v_row.b;
            c := v_row.c;
            d := v_row.d;
            exit; -- get out of the loop if there was a 'AA' 
          end ifs...;
         if v_row.type = 'BB' then
           nested ifs
             a := v_row.a;
             b := v_row.b;
             c := v_row.c;
             d := v_row.d;
             exit; -- get out of the loop if there was a 'BB' 
           end ifs...;
         end if
         repeat for 'CC' and 'DD'
       end loop;
     END;
    UPDATE TABLE_A
    SET COLUMN1=A,
        COLUMN2=B,
        COLUMN3=C,
        COLUMN4=D
    where cdid=i.cdid;
  END LOOP;
END;

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