OceanBase 金融專案最佳化案例

小至尖尖發表於2024-06-12

領導讓我幫忙支援下其他專案的SQL最佳化工作,呦西,是收集案例的好時機。😍

下面SQL都是在不能遠端的情況下,按照原SQL的邏輯等價改寫完成否發給現場同事驗證。


案例一

慢SQL,4.32秒:

SELECT MY_.*, RM
FROM (SELECT ROWNUM RM, V_.*
      FROM (SELECT *
            FROM (select count(1)        processidnum,
                         t.processid,
                         t.proc_name_ as procname
                  FROM tkdkdkdk t
                  WHERE 1 = 1
                    and (t.ASSIGNEE_ = 'server' or exists(select 1
                                                          FROM pepepep p
                                                          WHERE p.task_ = t.ID_
                                                            and (p.agent_userid_ = 'server' or
                                                                 (substr(p.groupid_, 6) in
                                                                  (select role_code
                                                                   FROM upupupup
                                                                   WHERE user_code = 'server') or
                                                                  p.userid_ = 'server'))))
                  GROUP BY t.processid, t.proc_name_)) V_
      WHERE ROWNUM <= 100000) MY_
WHERE RM >= 1;

慢SQL執行計劃:


改寫最佳化,445ms:

SELECT *
FROM (SELECT *
      FROM (SELECT a.*,
                   rownum rn
            FROM (SELECT count(1)        processidnum,
                         t.processid,
                         t.proc_name_ AS procname
                  FROM tkdkdkdk t
                           LEFT JOIN
                       (SELECT distinct p.task_
                        FROM pepepep p
                                 LEFT JOIN
                             (SELECT role_code
                              FROM upupupup
                              WHERE user_code = 'server'
                              GROUP BY role_code) tsu
                             ON (substr(p.groupid_, 6) = tsu.role_code)
                        WHERE (p.agent_userid_ = 'server'
                            OR (tsu.role_code is NOT null
                                OR p.userid_ = 'server'))) x
                       ON t.ID_ = x.task_
                  WHERE 1 = 1
                    AND (t.ASSIGNEE_ = 'server'
                      OR x.task_ is NOT NULL)
                  GROUP BY t.processid, t.proc_name_) a)
      WHERE rownum <= 100000)
WHERE rn >= 1; 

改寫最佳化後執行計劃:

最佳化思路:

  1、原SQL有很多子查詢,可能會導致計劃走NL,改成JOIN後讓CBO自動判斷是否走HASH還是NL。

  2、換了個標準的分頁框架。


案例二

慢SQL,2.6秒:

SELECT MY_.*, RM
FROM (SELECT ROWNUM RM, V_.*
      FROM (SELECT *
            FROM (select t.*, t.org_code || '-' || t.org_name as codename
                  FROM (select tc.*
                        FROM tgtgtgtg tc
                        start with TC.ORG_ID = '6000001'
                        connect by prior ORG_ID = tc.parent_id) t
                  WHERE org_level <= 3
                  ORDER BY CASE
                               WHEN ',' || nvl(null, 'fingard') || ',' like '%,' || ORG_ID || ',%' THEN CASE
                                                                                                            WHEN length(nvl(org_order, '')) = '9'
                                                                                                                then org_order || ''
                                                                                                            else '1' || org_code end
                               when length(nvl(org_order, '')) = '9' then '99999999' || org_order || ''
                               else '999999991' || org_code end)) V_
      WHERE ROWNUM <= 10) MY_;
WHERE RM >= 1;


改寫最佳化一,3.4秒:

SELECT MY_.*, RM
FROM (SELECT ROWNUM RM, V_.*
      FROM (SELECT *
            FROM (select a.*, a.org_code || '-' || a.org_name as codename
                  FROM (WITH t(
                               lv,
                               codename,
                               ORG_ID,
                               parent_id,
                               org_order,
                               org_code,
                               org_name,
                               org_level
                      ) AS (SELECT 1                                 as lv,
                                   tc.org_code || '-' || tc.org_name AS codename,
                                   tc.org_name,
                                   tc.ORG_ID,
                                   tc.parent_id,
                                   tc.org_order,
                                   tc.org_code,
                                   tc.org_level
                            FROM tgtgtgtg tc
                            WHERE tc.ORG_ID = '6000001'
                            UNION ALL
                            SELECT t.lv + 1,
                                   e.org_code || '-' || e.org_name AS codename,
                                   e.org_name,
                                   e.ORG_ID,
                                   e.parent_id,
                                   e.org_order,
                                   e.org_code,
                                   e.org_level
                            FROM tgtgtgtg e
                                     INNER JOIN t ON t.ORG_ID = e.parent_id)
                        SELECT *
                        FROM t) a
                  WHERE a.org_level <= 3
                  ORDER BY CASE
                               WHEN ',' || nvl(null, 'fingard') || ',' like '%,' || ORG_ID || ',%' THEN CASE
                                                                                                            WHEN length(nvl(org_order, '')) = '9'
                                                                                                                then org_order || ''
                                                                                                            else '1' || org_code end
                               when length(nvl(org_order, '')) = '9' then '99999999' || org_order || ''
                               else '999999991' || org_code end)) V_
      WHERE ROWNUM <= 10) MY_;
WHERE RM >= 1;

使用CTE遞迴改寫方案在PostgreSQL上是個通用的做法,也能取得比較好的效能效果。

但是在OB上反而效果更差點,NL運算元效能不夠強,使用NESTED-LOOP JOIN 效能反而沒有NESTED-LOOP CONNECT BY 運算元好。

OB研發在NESTED-LOOP JOIN運算元上還有繼續最佳化的空間。


改寫最佳化二,1.5秒:

既然使用NL效能不夠理想的情況下,就要想辦法使用HASH來最佳化SQL整體的執行效率。

將自動遞迴的方式改成手動。

1、首先需要知道資料整體的層級有多少。

SELECT DISTINCT lv
FROM (SELECT level lv
      FROM tgtgtgtg tc
      START WITH TC.ORG_ID = '6000001'
      CONNECT BY PRIOR ORG_ID = tc.parent_id) t; 

2、瞭解到整體的資料是13層,然後使用self join 將不同層級的資料關聯起來。

SELECT *
FROM (SELECT *
      FROM (SELECT a.*, rownum rn
            FROM (SELECT x.*
                  FROM (WITH tgtgtgtg AS
                                 (SELECT org_code, org_name, org_id, parent_id, org_order, org_level
                                  FROM tgtgtgtg)

                        SELECT 1                                 AS lv,
                               v1.org_code || '-' || v1.org_name AS codename,
                               v1.ORG_ID,
                               v1.parent_id,
                               v1.org_order,
                               v1.org_code,
                               v1.org_level
                        FROM tgtgtgtg v1
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 2                                 AS lv,
                               v2.org_code || '-' || v2.org_name AS codename,
                               v2.ORG_ID,
                               v2.parent_id,
                               v2.org_order,
                               v2.org_code,
                               v2.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 3                                 AS lv,
                               v3.org_code || '-' || v3.org_name AS codename,
                               v3.ORG_ID,
                               v3.parent_id,
                               v3.org_order,
                               v3.org_code,
                               v3.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 4                                 AS lv,
                               v4.org_code || '-' || v4.org_name AS codename,
                               v4.ORG_ID,
                               v4.parent_id,
                               v4.org_order,
                               v4.org_code,
                               v4.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 5                                 AS lv,
                               v5.org_code || '-' || v5.org_name AS codename,
                               v5.ORG_ID,
                               v5.parent_id,
                               v5.org_order,
                               v5.org_code,
                               v5.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 6                                 AS lv,
                               v6.org_code || '-' || v6.org_name AS codename,
                               v6.ORG_ID,
                               v6.parent_id,
                               v6.org_order,
                               v6.org_code,
                               v6.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 7                                 AS lv,
                               v7.org_code || '-' || v7.org_name AS codename,
                               v7.ORG_ID,
                               v7.parent_id,
                               v7.org_order,
                               v7.org_code,
                               v7.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 8                                 AS lv,
                               v8.org_code || '-' || v8.org_name AS codename,
                               v8.ORG_ID,
                               v8.parent_id,
                               v8.org_order,
                               v8.org_code,
                               v8.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                                 JOIN tgtgtgtg v8 ON v7.ORG_ID = v8.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 9                                 AS lv,
                               v9.org_code || '-' || v9.org_name AS codename,
                               v9.ORG_ID,
                               v9.parent_id,
                               v9.org_order,
                               v9.org_code,
                               v9.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                                 JOIN tgtgtgtg v8 ON v7.ORG_ID = v8.parent_id
                                 JOIN tgtgtgtg v9 ON v8.ORG_ID = v9.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 10                                  AS lv,
                               v10.org_code || '-' || v10.org_name AS codename,
                               v10.ORG_ID,
                               v10.parent_id,
                               v10.org_order,
                               v10.org_code,
                               v10.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                                 JOIN tgtgtgtg v8 ON v7.ORG_ID = v8.parent_id
                                 JOIN tgtgtgtg v9 ON v8.ORG_ID = v9.parent_id
                                 JOIN tgtgtgtg v10 ON v9.ORG_ID = v10.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 11                                  AS lv,
                               v11.org_code || '-' || v11.org_name AS codename,
                               v11.ORG_ID,
                               v11.parent_id,
                               v11.org_order,
                               v11.org_code,
                               v11.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                                 JOIN tgtgtgtg v8 ON v7.ORG_ID = v8.parent_id
                                 JOIN tgtgtgtg v9 ON v8.ORG_ID = v9.parent_id
                                 JOIN tgtgtgtg v10 ON v9.ORG_ID = v10.parent_id
                                 JOIN tgtgtgtg v11 ON v10.ORG_ID = v11.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 12                                  AS lv,
                               v12.org_code || '-' || v12.org_name AS codename,
                               v12.ORG_ID,
                               v12.parent_id,
                               v12.org_order,
                               v12.org_code,
                               v12.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                                 JOIN tgtgtgtg v8 ON v7.ORG_ID = v8.parent_id
                                 JOIN tgtgtgtg v9 ON v8.ORG_ID = v9.parent_id
                                 JOIN tgtgtgtg v10 ON v9.ORG_ID = v10.parent_id
                                 JOIN tgtgtgtg v11 ON v10.ORG_ID = v11.parent_id
                                 JOIN tgtgtgtg v12 ON v11.ORG_ID = v12.parent_id
                        WHERE v1.ORG_ID = '6000001'

                        UNION ALL

                        SELECT 13                                  AS lv,
                               v13.org_code || '-' || v13.org_name AS codename,
                               v13.ORG_ID,
                               v13.parent_id,
                               v13.org_order,
                               v13.org_code,
                               v13.org_level
                        FROM tgtgtgtg v1
                                 JOIN tgtgtgtg v2 ON v1.ORG_ID = v2.parent_id
                                 JOIN tgtgtgtg v3 ON v2.ORG_ID = v3.parent_id
                                 JOIN tgtgtgtg v4 ON v3.ORG_ID = v4.parent_id
                                 JOIN tgtgtgtg v5 ON v4.ORG_ID = v5.parent_id
                                 JOIN tgtgtgtg v6 ON v5.ORG_ID = v6.parent_id
                                 JOIN tgtgtgtg v7 ON v6.ORG_ID = v7.parent_id
                                 JOIN tgtgtgtg v8 ON v7.ORG_ID = v8.parent_id
                                 JOIN tgtgtgtg v9 ON v8.ORG_ID = v9.parent_id
                                 JOIN tgtgtgtg v10 ON v9.ORG_ID = v10.parent_id
                                 JOIN tgtgtgtg v11 ON v10.ORG_ID = v11.parent_id
                                 JOIN tgtgtgtg v12 ON v11.ORG_ID = v12.parent_id
                                 JOIN tgtgtgtg v13 ON v12.ORG_ID = v13.parent_id
                        WHERE v1.ORG_ID = '6000001') x
                  WHERE org_level <= 3
                  ORDER BY CASE
                               WHEN ',' || NVL(NULL, 'fingard') || ',' LIKE '%,' || ORG_ID || ',%' THEN
                                   CASE
                                       WHEN LENGTH(NVL(org_order, '')) = '9' THEN
                                           org_order || ''
                                       ELSE '1' || org_code
                                       END
                               WHEN LENGTH(NVL(org_order, '')) = '9' THEN
                                   '99999999' || org_order || ''
                               ELSE '999999991' || org_code END ) a)
      WHERE rownum <= 10)
WHERE rn >= 1;

現場同學差集比較,確認改寫後的SQL是等價的,執行時間從2.6秒降低到1.5秒能跑出結果。

原來18行的SQL改成了250多行後才最佳化了1秒的執行時間,實在沒其他辦法了,希望OB產研後續能CBO運算元繼續最佳化下。😂😂😂

相關文章