Mysql 分區介紹(九) —— 分區管理
阿新 • • 發佈：2018-04-02
mysql分區 mysql優化 分區優化 分區操作 一、分區操作
1. 將沒有分區的表改為分區表
ALTER TABLE trb3 PARTITION BY KEY(id) PARTITIONS 2;2. 刪除分區
# 刪除所有分區, 同時數據丟失
ALTER TABLE es2 REMOVE PARTITIONING;
# 刪除指定分區, 數據丟失
ALTER TABLE tr DROP PARTITION p2;3. SELECT指定分區查詢
select * from daily_rank_1_1 partition (p2015_04_24) limit 10;4. 添加分區
如果設置了MAXVALUE則無法添加新分區, 會提示 MAXVALUE can only be used in last partition definition, 這時可以使用修改分區來解決
ALTER TABLE members ADD PARTITION (PARTITION p3 VALUES LESS THAN (2010));5. 重新劃分分區
ALTER TABLE table1 REORGANIZE PARTITION 要修改的分區名(可以多個, 逗號分隔) INTO (
PARTITION 新分區1的名字 VALUES LESS THAN (值),
PARTITION 新分區2的名字 VALUES LESS THAN (值)
...
)修改一個分區成兩個分區
alter table daily_rank_1_1 reorganize partition p2015_04_28 into( partition p2015_04_28 values less than (to_days(‘2015-04-28‘)), partition pmax values less than(MAXVALUE) );
重新劃分多個分區
ALTER TABLE members REORGANIZE PARTITION p0,p1,p2,p3 INTO (
PARTITION m0 VALUES LESS THAN (1980),
PARTITION m1 VALUES LESS THAN (2000)
);分區修改的原則:<br />
-
- 不能與原方案有重疊
-
- 同時對多個分區劃分必須是連續的分區
-
- 分區類型不可以更改, 可以通過ALTER TABLE ... PARTITION BY ...實現
6. 修改分區數量(HASH/Key分區)
ALTER TABLE clients COALESCE PARTITION 4;
二、交換分區和子分區
支持交換分區的條件
-
- 表自身不是分區表
-
- 不是臨時表
-
- 兩個表的結構相同
-
- 表不包含外鍵
-
- 表的數據沒有出界
如果要執行操作, 必須具有DROP權限<br />
-
- 執行 ALTER TABLE ... EXCHANGE PARTITION不會在分區表或交換表上調用任何觸發器
-
- auto_increment會發生重置
具體操作:
pt是分區表, p是分區或子分區
1. 與非分區表交換分區
CREATE TABLE e (
id INT NOT NULL,
fname VARCHAR(30),
lname VARCHAR(30)
)
PARTITION BY RANGE (id) (
PARTITION p0 VALUES LESS THAN (50),
PARTITION p1 VALUES LESS THAN (100),
PARTITION p2 VALUES LESS THAN (150),
PARTITION p3 VALUES LESS THAN (MAXVALUE)
);
INSERT INTO e VALUES
(1669, "Jim", "Smith"),
(337, "Mary", "Jones"),
(16, "Frank", "White"),
(2005, "Linda", "Black");
mysql> CREATE TABLE e2 LIKE e;
Query OK, 0 rows affected (1.34 sec)
mysql> ALTER TABLE e2 REMOVE PARTITIONING;
Query OK, 0 rows affected (0.90 sec)
Records: 0 Duplicates: 0 Warnings: 0
# 將p0分區的數據寫入e2
ALTER TABLE e EXCHANGE PARTITION p0 WITH TABLE e2;如果沒有匹配到數據, 則提示Found row that does not match the partition
2. 交換一個子分區到一個沒有分區的表
mysql> CREATE TABLE es (
-> id INT NOT NULL,
-> fname VARCHAR(30),
-> lname VARCHAR(30)
-> )
-> PARTITION BY RANGE (id)
-> SUBPARTITION BY KEY (lname)
-> SUBPARTITIONS 2 (
-> PARTITION p0 VALUES LESS THAN (50),
-> PARTITION p1 VALUES LESS THAN (100),
-> PARTITION p2 VALUES LESS THAN (150),
-> PARTITION p3 VALUES LESS THAN (MAXVALUE)
-> );
Query OK, 0 rows affected (2.76 sec)
mysql> INSERT INTO es VALUES
-> (1669, "Jim", "Smith"),
-> (337, "Mary", "Jones"),
-> (16, "Frank", "White"),
-> (2005, "Linda", "Black");
Query OK, 4 rows affected (0.04 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> CREATE TABLE es2 LIKE es;
Query OK, 0 rows affected (1.27 sec)
mysql> ALTER TABLE es2 REMOVE PARTITIONING;
Query OK, 0 rows affected (0.70 sec)
Records: 0 Duplicates: 0 Warnings: 0
# 將p3sp0的數據交換到es2表
mysql> ALTER TABLE es EXCHANGE PARTITION p3sp0 WITH TABLE es2;
Query OK, 0 rows affected (0.29 sec)如果一個表擁有子分區, 則不能移動這個父分區到表中
三、分區維護
-
重建分區
刪除所有記錄存儲在分區，然後重新插入它們。整理碎片ALTER TABLE t1 REBUILD PARTITION p0, p1; -
優化分區
優化分區來回收未使用的空間和整理的分區中的數據文件ALTER TABLE t1 OPTIMIZE PARTITION p0, p1; - 分析分區
ALTER TABLE t1 ANALYZE PARTITION p3;-
檢查分區
ALTER TABLE trb3 CHECK PARTITION p1; -
修復分區
ALTER TABLE t1 REPAIR PARTITION p0,p1; - 獲取分區有效信息
mysql> SHOW CREATE TABLE trb3\G *************************** 1. row *************************** Table: trb3 Create Table: CREATE TABLE `trb3` ( `id` int(11) default NULL, `name` varchar(50) default NULL, `purchased` date default NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 PARTITION BY RANGE (YEAR(purchased)) ( PARTITION p0 VALUES LESS THAN (1990) ENGINE = MyISAM, PARTITION p1 VALUES LESS THAN (1995) ENGINE = MyISAM, PARTITION p2 VALUES LESS THAN (2000) ENGINE = MyISAM, PARTITION p3 VALUES LESS THAN (2005) ENGINE = MyISAM ) 1 row in set (0.00 sec)
select *
from INFORMATION_SCHEMA.PARTITIONS四、分區修剪
在執行sql時, 優化器會自動根據分區的條件, 進行分區選擇來提高性能。
分區修剪的條件: <br />
-
- partition_column = constant
-
- partition_column IN (constant1, constant2, ..., constantN)
where條件中包含<，>，< =，> =，和< > 等之間範圍查詢的時候, 就可以使用分區修剪
SELECT、UPDATE和DELETE都可以修剪分區, 但是INSERT無法修剪分區
- partition_column IN (constant1, constant2, ..., constantN)
五、分區選擇
在執行操作的時候優化器會根據語句自動進行修剪, 但是在有些時候是不同的:
- 要檢查的分區由語句的發布者指定，與分區剪枝不同，它是自動的。
- 而分區修剪僅適用於查詢，分區明確的選擇是查詢和多個DML語句支持。
支持的語句: SELECT、DELETE、INSERT、REPLACE、UPDATE、LOAD DATA.、LOAD XML.
具體的語句:
PARTITION (partition_names)
partition_names:
partition_name, ...SELECT * FROM employees PARTITION (p1);
mysql> SELECT * FROM employees PARTITION (p0, p2)
-> WHERE lname LIKE ‘S%‘;
+----+-------+-------+----------+---------------+
| id | fname | lname | store_id | department_id |
+----+-------+-------+----------+---------------+
| 4 | Jim | Smith | 2 | 4 |
| 11 | Jill | Stone | 1 | 4 |
+----+-------+-------+----------+---------------+
2 rows in set (0.00 sec)
mysql> SELECT id, CONCAT(fname, ‘ ‘, lname) AS name
-> FROM employees PARTITION (p0) ORDER BY lname;
+----+----------------+
| id | name |
+----+----------------+
| 3 | Ellen Johnson |
| 4 | Jim Smith |
| 1 | Bob Taylor |
| 2 | Frank Williams |
+----+----------------+
4 rows in set (0.06 sec)
mysql> SELECT store_id, COUNT(department_id) AS c
-> FROM employees PARTITION (p1,p2,p3)
-> GROUP BY store_id HAVING c > 4;
+---+----------+
| c | store_id |
+---+----------+
| 5 | 2 |
| 5 | 3 |
+---+----------+
2 rows in set (0.00 sec)你也可以使用PARTITION 在INSERT...SELECT語句上
mysql> CREATE TABLE employees_copy LIKE employees;
Query OK, 0 rows affected (0.28 sec)
mysql> INSERT INTO employees_copy
-> SELECT * FROM employees PARTITION (p2);
Query OK, 5 rows affected (0.04 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM employees_copy;
+----+--------+----------+----------+---------------+
| id | fname | lname | store_id | department_id |
+----+--------+----------+----------+---------------+
| 10 | Lou | Waters | 2 | 4 |
| 11 | Jill | Stone | 1 | 4 |
| 12 | Roger | White | 3 | 2 |
| 13 | Howard | Andrews | 1 | 2 |
| 14 | Fred | Goldberg | 3 | 3 |
+----+--------+----------+----------+---------------+
5 rows in set (0.00 sec)也可以在聯表中使用
CREATE TABLE stores (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
city VARCHAR(30) NOT NULL
)
PARTITION BY HASH(id)
PARTITIONS 2;
INSERT INTO stores VALUES
(‘‘, ‘Nambucca‘), (‘‘, ‘Uranga‘),
(‘‘, ‘Bellingen‘), (‘‘, ‘Grafton‘);
CREATE TABLE departments (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL
)
PARTITION BY KEY(id)
PARTITIONS 2;
INSERT INTO departments VALUES
(‘‘, ‘Sales‘), (‘‘, ‘Customer Service‘),
(‘‘, ‘Delivery‘), (‘‘, ‘Accounting‘);
mysql> SELECT
-> e.id AS ‘Employee ID‘, CONCAT(e.fname, ‘ ‘, e.lname) AS Name,
-> s.city AS City, d.name AS department
-> FROM employees AS e
-> JOIN stores PARTITION (p1) AS s ON e.store_id=s.id
-> JOIN departments PARTITION (p0) AS d ON e.department_id=d.id
-> ORDER BY e.lname;
+-------------+---------------+-----------+------------+
| Employee ID | Name | City | department |
+-------------+---------------+-----------+------------+
| 14 | Fred Goldberg | Bellingen | Delivery |
| 5 | Mary Jones | Nambucca | Sales |
| 17 | Mark Morgan | Bellingen | Delivery |
| 9 | Andy Smith | Nambucca | Delivery |
| 8 | June Wilson | Bellingen | Sales |
+-------------+---------------+-----------+------------+
5 rows in set (0.00 sec)刪除中使用分區選擇
mysql> SELECT * FROM employees WHERE fname LIKE ‘j%‘;
+----+-------+--------+----------+---------------+
| id | fname | lname | store_id | department_id |
+----+-------+--------+----------+---------------+
| 4 | Jim | Smith | 2 | 4 |
| 8 | June | Wilson | 3 | 1 |
| 11 | Jill | Stone | 1 | 4 |
+----+-------+--------+----------+---------------+
3 rows in set (0.00 sec)
mysql> DELETE FROM employees PARTITION (p0, p1)
-> WHERE fname LIKE ‘j%‘;
Query OK, 2 rows affected (0.09 sec)
mysql> SELECT * FROM employees WHERE fname LIKE ‘j%‘;
+----+-------+-------+----------+---------------+
| id | fname | lname | store_id | department_id |
+----+-------+-------+----------+---------------+
| 11 | Jill | Stone | 1 | 4 |
+----+-------+-------+----------+---------------+
1 row in set (0.00 sec)更新中使用分區選擇
mysql> UPDATE employees PARTITION (p0)
-> SET store_id = 2 WHERE fname = ‘Jill‘;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 0 Changed: 0 Warnings: 0
mysql> SELECT * FROM employees WHERE fname = ‘Jill‘;
+----+-------+-------+----------+---------------+
| id | fname | lname | store_id | department_id |
+----+-------+-------+----------+---------------+
| 11 | Jill | Stone | 1 | 4 |
+----+-------+-------+----------+---------------+
1 row in set (0.00 sec)
mysql> UPDATE employees PARTITION (p2)
-> SET store_id = 2 WHERE fname = ‘Jill‘;
Query OK, 1 row affected (0.09 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM employees WHERE fname = ‘Jill‘;
+----+-------+-------+----------+---------------+
| id | fname | lname | store_id | department_id |
+----+-------+-------+----------+---------------+
| 11 | Jill | Stone | 2 | 4 |
+----+-------+-------+----------+---------------+
1 row in set (0.00 sec)INSERT和REPLACE INTO使用分區選擇
mysql> INSERT INTO employees PARTITION (p2) VALUES (20, ‘Jan‘, ‘Jones‘, 1, 3);
ERROR 1729 (HY000): Found a row not matching the given partition set
mysql> INSERT INTO employees PARTITION (p3) VALUES (20, ‘Jan‘, ‘Jones‘, 1, 3);
Query OK, 1 row affected (0.07 sec)
mysql> REPLACE INTO employees PARTITION (p0) VALUES (20, ‘Jan‘, ‘Jones‘, 3, 2);
ERROR 1729 (HY000): Found a row not matching the given partition set
mysql> REPLACE INTO employees PARTITION (p3) VALUES (20, ‘Jan‘, ‘Jones‘, 3, 2);
Query OK, 2 rows affected (0.09 sec)六、分區的限制
-
- 無法使用存儲過程、存儲功能、UDF和插件
-
- 無法用戶變量或聲明變量
-
- 不允許位操作
七、性能影響
-
- 分區的創建、修改、刪除取決於文件系統。應該確保large_files_support啟用，open_files_limit設置正確
-
- 在執行分區操作時需要上寫鎖, 但是不影響查詢, 分區操作完成後會立即執行插入和更新操作
-
- 分區操作， 查詢、更新往往是MYISAM比INNODB更快
-
- 使用索引可以在非分區表提高性能, 使用分區修剪也可以顯著的提高性能
-
- 加載數據使用緩沖來提高性能。您應該知道緩沖區每分區使用130KB內存來實現這一點。
-
- Mysql5.6.7之前, 分區最大數為1024個, 從5.6.7開始, 分區表的數最多是8192個, 包括子分區
-
- 分區表不支持查詢緩存
Mysql 分區介紹(九) —— 分區管理