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这篇文章主要介绍数据库中如何高效率删除大表历史数据，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
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清理大表历史数据
通过将非分区表Online Redefinition转换为以删除条件为Range范围分区的Partition-ed Table，再直接Truncate Partiton的方法来加速历史数据的清理，
同时又不影响业务的在线。
create table order_history as select * from dba_objects;
select count(*) from order_history;
select count(*) from order_history where created < sysdate-365;
COUNT(*)
———-
49983
收集统计信息
exec dbms_stats.gather_table_stats('SCOTT','ORDER_HISTORY');
create table order_history_int(
OWNER VARCHAR2(30),
OBJECT_NAME VARCHAR2(128),
SUBOBJECT_NAME VARCHAR2(30),
OBJECT_ID NUMBER,
DATA_OBJECT_ID NUMBER,
OBJECT_TYPE VARCHAR2(19),
CREATED DATE,
LAST_DDL_TIME DATE,
TIMESTAMP VARCHAR2(19),
STATUS VARCHAR2(7),
TEMPORARY VARCHAR2(1),
GENERATED VARCHAR2(1),
SECONDARY VARCHAR2(1))
partition by range(created)
( partition p1 values less than (to_date('2010-01-01','YYYY-MM-DD')) tablespace users,
partition p2 values less than (to_date('2011-01-01','YYYY-MM-DD')) tablespace users,
partition p3 values less than (to_date('2012-01-01','YYYY-MM-DD')) tablespace users,
partition p4 values less than (to_date('2013-01-01','YYYY-MM-DD')) tablespace users,
partition p5 values less than (maxvalue) tablespace users);
begin
dbms_redefinition.can_redef_table(uname => 'SCOTT',
tname => 'ORDER_HISTORY',
options_flag => DBMS_REDEFINITION.CONS_USE_ROWID);
end;
/
begin
DBMS_REDEFINITION.START_REDEF_TABLE(uname => 'SCOTT',
orig_table => 'ORDER_HISTORY',
int_table => 'ORDER_HISTORY_INT',
options_flag => DBMS_REDEFINITION.cons_use_rowid);
end;
/
SQL> select count(*) from ORDER_HISTORY_INT;
COUNT(*)
———-
50731
DECLARE
num_errors PLS_INTEGER;
BEGIN
DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS(uname => 'SCOTT',
orig_table => 'ORDER_HISTORY',
int_table => 'ORDER_HISTORY_INT',
copy_indexes => 0,
copy_triggers => TRUE,
copy_constraints => FALSE,
copy_privileges => TRUE,
ignore_errors => FALSE,
num_errors => num_errors,
copy_statistics => TRUE);
END;
/
begin
dbms_redefinition.finish_redef_table(uname => 'SCOTT',
orig_table => 'ORDER_HISTORY',
int_table => 'ORDER_HISTORY_INT');
end;
/
alter table ORDER_HISTORY truncate partition p1;
alter table ORDER_HISTORY truncate partition p2;
alter table ORDER_HISTORY truncate partition p3;
SQL> select count(*) from ORDER_HISTORY;
COUNT(*)
———-
748
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