概述

有這麼個需求，有一張5000萬大表，需要保留最後3個月數據，也就是1000萬數據，而這張表使用很頻繁，生產環境也是7*24小時不停，如果用分段delete影響的時間太長，所以用了rename切換的方法。這裡先在測試數據庫做一下演練。

以測試環境BN_SEQUENCE表做測試，數據量大約是6千萬。

思路

最近有點喜歡上畫圖，感覺形象點，可能有點丑，大家不要介意~

實現方案

1、獲取A表定義、索引、觸發器、外鍵約束

這裡的表定義、索引、主外鍵實際上用PLSQL就可以直接看到了，所以就不寫了，只寫了觸發器的。

相關sql:

--查看錶上觸發器定義
SELECT * FROM DBA_TRIGGERS WHERE TABLE_NAME='BN_SEQUENCE';
SELECT DBMS_METADATA.GET_DDL('TRIGGER','CHK_BIU_BN_SEQUENCE','GLOGOWNER') FROM DUAL;
SELECT DBMS_METADATA.GET_DDL('TRIGGER','BN_SEQUENCE_PN','GLOGOWNER') FROM DUAL;
-- Create table
create table BN_SEQUENCE
(
 BN_RULE_GID VARCHAR2(101 CHAR) not null,
 BN_CONTEXT VARCHAR2(300 CHAR) not null,
 BN_SEQUENCE_ID VARCHAR2(50 CHAR) not null,
 CURVALUE VARCHAR2(50 CHAR),
 DOMAIN_NAME VARCHAR2(50 CHAR) not null,
 INSERT_USER VARCHAR2(128 CHAR) not null,
 INSERT_DATE DATE not null,
 UPDATE_USER VARCHAR2(128 CHAR),
 UPDATE_DATE DATE
)
tablespace DATA
 pctfree 10
 initrans 1
 maxtrans 255
 storage
 (
 initial 1
 next 1
 minextents 1
 maxextents unlimited
 pctincrease 0
 );
.....

2、創建B表–BN_SEQUENCE_BAK

--這裡只創建表定義,不加約束、索引、觸發器、外鍵
-- Create table
create table BN_SEQUENCE_BAK
(
 BN_RULE_GID VARCHAR2(101 CHAR) not null,
 BN_CONTEXT VARCHAR2(300 CHAR) not null,
 BN_SEQUENCE_ID VARCHAR2(50 CHAR) not null,
 CURVALUE VARCHAR2(50 CHAR),
 DOMAIN_NAME VARCHAR2(50 CHAR) not null,
 INSERT_USER VARCHAR2(128 CHAR) not null,
 INSERT_DATE DATE not null,
 UPDATE_USER VARCHAR2(128 CHAR),
 UPDATE_DATE DATE
)
tablespace DATA
 pctfree 10
 initrans 1
 maxtrans 255
 storage
 (
 initial 1
 next 1
 minextents 1
 maxextents unlimited
 pctincrease 0
 );

3、分段insert

為了避免對線上環境的影響，建議分段insert，插入最近3個月的數據。

insert into BN_SEQUENCE_BAK select * from BN_SEQUENCE where update_date >=to_date('2019/08/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss') and
update_date <to_date('2019/09/19 14:00:00', 'yyyy/mm/dd hh24:mi:ss');
insert into BN_SEQUENCE_BAK select * from BN_SEQUENCE where update_date >=to_date('2019/07/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss') and
update_date <to_date('2019/08/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss');
insert into BN_SEQUENCE_BAK select * from BN_SEQUENCE where update_date >=to_date('2019/06/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss') and
update_date <to_date('2019/07/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss');
insert into BN_SEQUENCE_BAK select * from BN_SEQUENCE where update_date >=to_date('2018/06/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss') and
update_date <to_date('2019/06/19 00:00:00', 'yyyy/mm/dd hh24:mi:ss');

4、切換表

這裡實際上我在生產環境做切換也踏坑了，沒考慮到有物化視圖這種情況，所以導致切換不了。

alter table BN_SEQUENCE rename to BN_SEQUENCE_ARCH;
alter table BN_SEQUENCE_BAK rename to BN_SEQUENCE;

5、數據補錄

把前面插入數據後到切換表後的數據做一下補錄。

insert into BN_SEQUENCE select * from BN_SEQUENCE_ARCH where update_date >=to_date('2019/09/19 14:00:00', 'yyyy/mm/dd hh24:mi:ss')

6、B表創建索引、觸發器

記得需要重命名。

-- Add comments to the table 
comment on table BN_SEQUENCE
 is 'This table stores the current sequence value of the business number.';
-- Add comments to the columns 
comment on column BN_SEQUENCE.BN_RULE_GID
 is 'BN_RULE_GID contains the unique identifier for the Business Number (BN) rule.';
-- Create/Recreate primary, unique and foreign key constraints 
alter table BN_SEQUENCE
 add constraint PK_BN_SEQUENCE primary key (BN_RULE_GID, BN_CONTEXT, BN_SEQUENCE_ID)
 using index 
 tablespace INDX
 pctfree 10
 initrans 2
 maxtrans 255
 storage
 (
 initial 1M
 next 1M
 minextents 1
 maxextents unlimited
 pctincrease 0
 );
alter table BN_SEQUENCE
 add constraint FK_BN_SEQRULE_GID foreign key (BN_RULE_GID)
 references BN_RULE (BN_RULE_GID);
-- Grant/Revoke object privileges 
grant select, insert, update, delete on BN_SEQUENCE to APP_USER;
grant select on BN_SEQUENCE to APP_USER_SELECT;
grant select, insert, update, delete on BN_SEQUENCE to EXT_USER;
....