将 BULK COLLECT 与 rownum 一起使用

Question

下面的查询执行批量 select 然后循环更新记录。我想在这里使用 BULK COLLECT INTO 和 FORALL 构造来改进 performance.But 查询使用 rownum 来更新循环中的列。无论如何我也可以在获取 rownum 的同时使用 BULK COLLECT INTO 吗？

     FOR rec IN
        (SELECT rownum rn,
            b.*
        FROM
            (SELECT *
            FROM temp_final a
           WHERE reid  = 1
            AND retype  = 9
            AND sid         = 'r123'
            AND pid = 2191
            ORDER BY a.horder DESC nulls last,
                sname                         ,
                rowgroup                           ,
                dpct DESC nulls last       ,
                name
            ) b
        )
        LOOP
            UPDATE temp_final
            SET horder=rec.rn
             WHERE reid  = 1
            AND retype  = 9
            AND sid         = 'r123'
            AND pid = 2191
            AND mid   =rec.mid;
        END LOOP;

谢谢

Answer 1

您可以获取 rowid 以及初始 select，将批次转储到数组中，然后在您的 FORALL 中使用它，例如

declare
  l_num_list sys.odcinumberlist := sys.odcinumberlist();
  l_char_list sys.odcivarchar2list := sys.odcivarchar2list();
begin  
SELECT rownum rn,rowidtochar(rid)
bulk collect into l_num_list, l_char_list
FROM
            (SELECT a.*, rowid rid
            FROM temp_final a
           WHERE reid  = 1
            AND retype  = 9
            AND sid         = 'r123'
            AND pid = 2191
            ORDER BY a.horder DESC nulls last,
                sname                         ,
                rowgroup                           ,
                dpct DESC nulls last       ,
                name
            ) b;

forall i in 1 .. l_num_list.count
            UPDATE temp_final
            SET horder=l_num_list(i)
            WHERE rowid = chartorowid(l_char_list(i));

end;
/

Answer 2

您不需要批量收集，您的 pl/sql 更新尝试做的事情可以重写为单个 MERGE INTO 语句，这比使用 FORALL.如果你还是坚持使用forall，可以把这个MERGE转成forall块。

MERGE INTO temp_final tgt USING (
    SELECT rowid,
        ROW_NUMBER() OVER(
            ORDER BY
                horder DESC NULLS LAST,sname,rowgroup,dpct DESC NULLS LAST,name
        ) rn
    FROM
        temp_final
    WHERE
        reid = 1
        AND retype = 9
        AND sid = 'r123'
        AND pid = 2191
)
src ON ( tgt.rowid = src.rowid )
WHEN MATCHED THEN UPDATE SET tgt.horder = src.rn;

将 BULK COLLECT 与 rownum 一起使用

Using BULK COLLECT with rownum

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