系統臨時表空間已經達到64G， 但是依然報ORA-1652錯誤，現在業務申請擴充套件臨時表空間到128g。

  經過抓取AWR報告，發現如下幾條sql語句執行時間最長，經過分析 發現 大部分是 “MINUS ”和“insert into select......”型別語句。重點關注 MINUS。

看Top10事件，direct path write temp 出現次數很多，大量等待User I/O，檢視執行時間最長的SQL：

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INSERT INTO CAMS_ACCT_TEMP03 SELECT * FROM CAMS_ACCT_TEMP01 A WHERE NOT  EXISTS(SELECT 1 FROM CAMS_ACCT_TEMP03 B WHERE A.ACCT_NO = B.ACCT_NO) MINUS SELECT * FROM CAMS_ACCT_TEMP02 A WHERE NOT EXISTS(SELECT 1 FROM CAMS_ACCT_TEMP03 B WHERE A.ACCT_NO = B.ACCT_NO)；

 

  INSERT INTO CAMS_CUST_TEMP03 SELECT * FROM CAMS_CUST_TEMP01 MINUS SELECT * FROM CAMS_CUST_TEMP02；
 

 

INSERT INTO CAMS_SUB_ACCT_TEMP (COMPANY, OPEN_BANK, ACCT_NO, SUB_ACCT_NO, INTERNAL_KEY) (SELECT COMPANY, OPEN_BANK, ACCT_NO, SUB_ACCT_NO, INTERNAL_KEY FROM    INTF_CAMS_SUB_ACCT WHERE DATA_DATE = :B1 MINUS SELECT COMPANY, OPEN_BANK, ACCT_NO, SUB_ACCT_NO, INTERNAL_KEY FROM INTF_CAMS_SUB_ACCT WHERE DATA_DATE = :B2 )；
 

 

INSERT INTO CAMS_CARD_INFO_TEMP03 SELECT * FROM CAMS_CARD_INFO_TEMP01 MINUS SELECT * FROM CAMS_CARD_INFO_TEMP02；

 

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INSERT INTO CAMS_CUST_TEMP01 (COMPANY , ORG_CODE , CUST_NO , CUST_NAME , CERTI_KIND , CERTI_NO , EFFECTIVE_DATE , ISSUE_ORGAN_REGION , IDENTITY_KIND , COUNTRY , SEX , POST_CODE , ADDRESS , TEL , DATA_STATE , AUDITING_STATE , ERROR_REASON , REPORT_DATE , REPORT_FILE , UPD_USER , UPD_TIME ) SELECT COMPANY , ORG_CODE , CUST_NO , CUST_NAME , CERTI_KIND , CERTI_NO , EFFECTIVE_DATE , ISSUE_ORGAN_REGION , IDENTITY_KIND , COUNTRY , SEX , POST_CODE , ADDRESS , TEL , DATA_STATE , AUDITING_STATE , ERROR_REASON , REPORT_DATE , REPORT_FILE , UPD_USER , UPD_TIME FROM INTF_CAMS_CUST A WHERE A.DATA_DATE = :B1；

首先我們來了解下 ‘MINUS’函式，minus主要作用在於取兩個 集合/表 補集，就類似對兩個集合排序 然後類似冒泡演算法對比去重。

 

抓了2個sql的執行計劃，可以發現使用了大量的temp排序，一條sql執行消耗800+MB的temp 排序，可以通過 not in ,not exists 來改寫，實際工作中，not in比not exists要好。

對於需要排序的列，可以適當建立索引，走索引掃描可以避免額外排序。

SQL1:

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-------------------------------------

SELECT * FROM IGRSVISE.CAMS_ACCT_TEMP01 A WHERE NOT EXISTS( SELECT 1 FROM IGRSVISE.CAMS_ACCT_TEMP03 B WHERE A.ACCT_NO = B.ACCT_NO) 

MINUS

SELECT * FROM IGRSVISE.CAMS_ACCT_TEMP02 A WHERE NOT EXISTS( SELECT 1 FROM IGRSVISE.CAMS_ACCT_TEMP03 B WHERE A.ACCT_NO = B.ACCT_NO)

SQL2:

INSERT INTO CAMS_CUST_TEMP03 SELECT * FROM IGRSVISE.CAMS_CUST_TEMP01 MINUS SELECT * FROM IGRSVISE.CAMS_CUST_TEMP02

改寫成如下 not in 

SQL3 :

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INSERT INTO CAMS_CUST_TEMP01 (COMPANY ,ORG_CODE ,CUST_NO ,CUST_NAME
,CERTI_KIND ,CERTI_NO ,EFFECTIVE_DATE ,ISSUE_ORGAN_REGION
,IDENTITY_KIND ,COUNTRY ,SEX ,POST_CODE ,ADDRESS ,TEL ,DATA_STATE
,AUDITING_STATE ,ERROR_REASON ,REPORT_DATE ,REPORT_FILE ,UPD_USER
,UPD_TIME ) SELECT COMPANY ,ORG_CODE ,CUST_NO ,CUST_NAME ,CERTI_KIND
,CERTI_NO ,EFFECTIVE_DATE ,ISSUE_ORGAN_REGION ,IDENTITY_KIND ,COUNTRY
,SEX ,POST_CODE ,ADDRESS ,TEL ,DATA_STATE ,AUDITING_STATE ,ERROR_REASON
,REPORT_DATE ,REPORT_FILE ,UPD_USER ,UPD_TIME FROM INTF_CAMS_CUST A
WHERE A.DATA_DATE = :B1

SQL4：

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INSERT INTO CAMS_CARD_INFO_TEMP01 (COMPANY, ORG_CODE, CARD_NO,IS_PRIMARY_CARD, MATURITY_DATE, ACCT_MEDIUM, CLOSED_DATE, CARD_STATUS,ERROR_REASON, REPORT_DATE, REPORT_FILE, UPD_USER, UPD_TIME,MAIN_CARD_NO ) 
SELECT COMPANY, ORG_CODE, CARD_NO, IS_PRIMARY_CARD,MATURITY_DATE, ACCT_MEDIUM, CLOSED_DATE, CARD_STATUS, ERROR_REASON,REPORT_DATE, REPORT_FILE, UPD_USER, UPD_TIME, MAIN_CARD_NO FROM INTF_CAMS_CARD_INFO A WHERE A.DATA_DATE = :B1

臨時表還有一種優化方法，類似這種：

with 
cr as 
( 
    select code from product where Name like 'C%' 
)

select * from product where code in (select * from cr)