【发布时间】：2019-10-12 16:42:42
【问题描述】：
此查询查找 K2 的 W_G 是什么（例如：“L_E”被“E1”找到）。 然后它找到K1是什么（例如：'IS'被'E1'找到）。 然后根据 K1,K2('30','10' by 'IS' and 'C01A') 找到 K4,K5。
为了加快这个查询，有什么东西可以修改这个查询吗？
执行计划如下。
----------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 5 (0)| 00:00:01 |
| 1 | VIEW | | 1 | 13 | 2 (0)| 00:00:01 |
| 2 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6617_CD798E | 1 | 26 | 2 (0)| 00:00:01 |
| 3 | TEMP TABLE TRANSFORMATION | | | | | |
| 4 | LOAD AS SELECT | SYS_TEMP_0FD9D6618_CD798E | | | | |
|* 5 | TABLE ACCESS FULL | C_W_B | 1 | 273 | 3 (0)| 00:00:01 |
| 6 | VIEW | | 1 | 13 | 2 (0)| 00:00:01 |
| 7 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6617_CD798E | 1 | 26 | 2 (0)| 00:00:01 |
|* 8 | VIEW | | 1 | 39 | 2 (0)| 00:00:01 |
| 9 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6618_CD798E | 1 | 273 | 2 (0)| 00:00:01 |
| 10 | SORT AGGREGATE | | 1 | 13 | | |
| 11 | VIEW | | 1 | 13 | 2 (0)| 00:00:01 |
| 12 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6618_CD798E | 1 | 273 | 2 (0)| 00:00:01 |
| 13 | TEMP TABLE TRANSFORMATION | | | | | |
| 14 | LOAD AS SELECT | SYS_TEMP_0FD9D6617_CD798E | | | | |
|* 15 | TABLE ACCESS FULL | C_W_B | 1 | 78 | 3 (0)| 00:00:01 |
| 16 | FAST DUAL | | 1 | | 2 (0)| 00:00:01 |
----------------------------------------------------------------------------------------------------------
Statistics
----------------------------------------------------------
4 recursive calls
16 db block gets
30 consistent gets
2 physical reads
1156 redo size
682 bytes sent via SQL*Net to client
416 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
标签在下面
CREATE TABLE C_W_B (
HE VARCHAR2(22),
WE VARCHAR2(22),
G_D VARCHAR2(22),
W_G VARCHAR2(22),
W_V VARCHAR2(22),
K1 VARCHAR2(22),
K2 VARCHAR2(22),
K3 VARCHAR2(22),
K4 VARCHAR2(22),
K5 VARCHAR2(22),
K6 VARCHAR2(22),
K7 VARCHAR2(22),
K8 VARCHAR2(22),
K9 VARCHAR2(22),
K10 VARCHAR2(22),
K11 VARCHAR2(22),
K12 VARCHAR2(22),
K13 VARCHAR2(22),
K14 VARCHAR2(22),
K22 VARCHAR2(22),
K16 VARCHAR2(22)
);
数据如下
INSERT INTO C_W_B(HE,WE,G_D,W_G,W_V,K1,K3,K4,K6) VALUES
('C6','61','R3','L_C_F','1','IS','C01A','30','10');
INSERT INTO C_W_B(HE,WE,G_D,W_G,K1,K2) VALUES
('C6','61','R3','L_E','IS','E1');
查询如下
WITH G_S AS (
SELECT /*+FIRST_ROWS(1)*/
A.W_G, A.K1
FROM C_W_B A
WHERE 1=1
AND A.HE = 'C6'AND A.WE = '61' AND A.G_D ='R3' AND A.K2='E1'
)
SELECT CASE
WHEN (SELECT A.W_G FROM G_S A)='L_E'
THEN (
WITH SEO AS (
SELECT A.K1 FROM G_S A
),
SE AS (SELECT *
FROM C_W_B B
WHERE B.W_G = 'L_C_F'
AND B.HE = 'C6'
AND B.WE = '61'
AND B.G_D ='R3'
AND B.K1 = (SELECT K1 FROM SEO)
AND B.K3 LIKE 'C01A'
)
SELECT (L_T /QT*1000)
FROM ( SELECT NVL(TO_NUMBER(K4),0) AS L_T,
NVL(TO_NUMBER(K6),0) AS QT
FROM SE
WHERE W_V IN (SELECT TO_CHAR(MAX(TO_NUMBER(W_V))) FROM SE )
)
)
WHEN 1=2
THEN TO_NUMBER(0)
ELSE TO_NUMBER(0)
END
FROM DUAL;
【问题讨论】：
-
现在这个查询的访问时间是多少？
-
您的查询中有很多无用的东西。比如
TO_CHAR(MAX(TO_NUMBER(W_V)))，为什么用数字和字符圈起来？显然 CTEG_S只返回一行 - 将dual替换为G_S。我个人不喜欢这些嵌入式子查询。也许尝试将所有表放在一个“FROM”子句中。我认为您不需要超过 1-2 个子查询。 -
表的统计信息是最新的吗？
标签： sql oracle query-performance