Mysql --分割槽(3)range分割槽
阿新 • • 發佈:2019-01-30
3.分割槽型別
RANGE分割槽
按照range分割槽的表是利用取值範圍將資料分成分割槽,區間要連續並且不能互相重疊,使用values less than操作符進行分割槽定義
CREATE TABLE tnp (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(255),
PRIMARY KEY pk (id)
)
partition by range (id) (
partition p0 values less than(10),
partition p1 values less than(20),
partition p2 values less than(30)
);
當插入ID大於30的值是,會出現錯誤
可以在設定分割槽時使用values less than maxvalue子句
alter table tnp add partition(partition p3 values less than maxvalue);
MySQL支援在values less than子句中使用表示式,比如,以日期作為range分割槽的分割槽列:
CREATE TABLE emp_date (
id INT NOT NULL auto_increment,
name VARCHAR(255),
hiredate date not null default '1970-01-01',
key (id)
)
partition by range (year(hiredate)) (
partition p0 values less than(1995),
partition p1 values less than(2000),
partition p2 values less than(2005)
);
MySQL也支援對TIMESTAMP列進行range分割槽
CREATE TABLE quarterly_report_status (
report_id INT NOT NULL,
report_status VARCHAR(20 ) NOT NULL,
report_updated TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)
PARTITION BY RANGE ( UNIX_TIMESTAMP(report_updated) ) (
PARTITION p0 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-01-01 00:00:00') ),
PARTITION p1 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-04-01 00:00:00') ),
PARTITION p2 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-07-01 00:00:00') ),
PARTITION p3 VALUES LESS THAN ( UNIX_TIMESTAMP('2008-10-01 00:00:00') ),
PARTITION p4 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-01-01 00:00:00') ),
PARTITION p5 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-04-01 00:00:00') ),
PARTITION p6 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-07-01 00:00:00') ),
PARTITION p7 VALUES LESS THAN ( UNIX_TIMESTAMP('2009-10-01 00:00:00') ),
PARTITION p8 VALUES LESS THAN ( UNIX_TIMESTAMP('2010-01-01 00:00:00') ),
PARTITION p9 VALUES LESS THAN (MAXVALUE)
);
實際是是將TMESTAMP型別通過UNIX_TIMESTAMP函式轉換成INT型
mysql> select UNIX_TIMESTAMP('2008-01-01 00:00:00');
+---------------------------------------+
| UNIX_TIMESTAMP('2008-01-01 00:00:00') |
+---------------------------------------+
| 1199116800 |
+---------------------------------------+
1 row in set (0.00 sec)
delimiter $$
drop procedure if exists pr_insertdate_2$$
create procedure pr_insertdate_2(in begindate date,in enddate date,in tabname varchar(40))
begin
set begindate = timestamp(begindate);
while begindate<enddate
do
set @s=concat_ws(' ','insert into',tabname,'values(1,''true'',''',begindate,''')');
prepare stmt from @s;
execute stmt;
drop prepare stmt;
set begindate = date_add(begindate,interval 1 day);
end while;
end$$
delimiter ;
mysql> call pr_insertdate_2('2007-01-01','2010-12-31','quarterly_report_status');
Query OK, 0 rows affected (0.32 sec)
mysql> select
-> partition_name part,
-> partition_expression expr,
-> partition_description descr,
-> table_rows
-> from information_schema.partitions where
-> table_schema = schema()
-> and table_name='quarterly_report_status';
+------+---------------------------------+------------+------------+
| part | expr | descr | table_rows |
+------+---------------------------------+------------+------------+
| p0 | UNIX_TIMESTAMP(report_updated) | 1199116800 | 365 |
| p1 | UNIX_TIMESTAMP(report_updated) | 1206979200 | 91 |
| p2 | UNIX_TIMESTAMP(report_updated) | 1214841600 | 91 |
| p3 | UNIX_TIMESTAMP(report_updated) | 1222790400 | 92 |
| p4 | UNIX_TIMESTAMP(report_updated) | 1230739200 | 92 |
| p5 | UNIX_TIMESTAMP(report_updated) | 1238515200 | 90 |
| p6 | UNIX_TIMESTAMP(report_updated) | 1246377600 | 91 |
| p7 | UNIX_TIMESTAMP(report_updated) | 1254326400 | 92 |
| p8 | UNIX_TIMESTAMP(report_updated) | 1262275200 | 92 |
| p9 | UNIX_TIMESTAMP(report_updated) | MAXVALUE | 364 |
+------+---------------------------------+------------+------------+
10 rows in set (0.00 sec)
涉及TIMESTAMP值的任何其他表示式不允許 (See Bug #42849.)
當一個或多個下列條件為真時,範圍分割槽是特別有用的:
1.需要解除安裝舊資料
此時你就可以使用 ALTER TABLE employees DROP PARTITION p0;解除安裝舊資料,效率要比delete高很多
2.你想用一列包含日期或時間值,或包含從其他系列所產生的價值
You want to use a column containing date or time values, or containing values arising from some other series
3.where條件列經常為分割槽列。這個不用多說了,利用分割槽裁剪特性