Oracle hash分区
原创
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1.创建表
create table t1
(
id varchar2(10),
name varchar2(20)
)
partition by hash(id)
(
partition p1,
partition p2,
partition p3
);
2.查看数据
insert into t1 values('p1',1);
insert into t1 values('p1',2);
insert into t1 values('p3',3);
3.查看数据
SQL> select * from t1;
ID NAME
------------------------------ ------------------------------------------------------------
p1 1
p1 2
p3 3
SQL> select * from t1 partition(p1);
ID NAME
------------------------------ ------------------------------------------------------------
p1 1
p1 2
SQL> select * from t1 partition(p2);
no rows selected
SQL> select * from t1 partition(p3);
ID NAME
------------------------------ ------------------------------------------------------------
p3 3
4.存储过程插入大量数据
declare
i number;
begin
for i in 1..1000000 loop
insert into t1 values(i,'name');
end loop;
commit;
end;
/
5.查看每个分区的数据,可以看出,存在数据倾斜。
SQL> select count(1) from t1 partition(p1);
COUNT(1)
----------
249867
SQL> select count(1) from t1 partition(p2);
COUNT(1)
----------
500616
SQL> select count(1) from t1 partition(p3);
COUNT(1)
----------
249517
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Linux,oracle