測試資料準備800萬條資料,這裡通過存儲過程導入資料
do
insert into part_tab
values (v,'testing partitions',adddate('1995-01-01',(rand(v)*36520) mod 3652));
set v = v + 1;
end while;
end
delimiter ;
call load_part_tab();
#導入末分區表中資料
insert into no_part_tab select * from part_tab;
#查詢資料庫的數量
SELECT count(*) FROM part_tab; //8000000
#測試sql性能
#分區之後的資料時間
select count(*) from part_tab where c3 > date '1995-01-01' and c3 < date '1995-12-31';
花費時間 0.138s
#未分區的資料
select count(*) from no_part_tab where c3 > date '1995-01-01' and c3 < date '1995-12-31';
花費時間1.166s
通過explain關鍵字進行分析
分區表的資料分析
EXPLAIN select count(*) from part_tab where c3 > date '1995-01-01' and c3 < date '1995-12-31';
未分區表的資料分析
explain select count(*) from no_part_tab where c3 > date '1995-01-01' and c3 < date '1995-12-31';
結果如下:
對沒有分區的資料進行加索引進行測試
create index idx_of_c3 on no_part_tab (c3)
#建立索引執行時間24.008s
建立索引執行
select count(*) from no_part_tab where c3 > date '1995-01-01' and c3 < date '1995-12-31';
花費時間:0.198s
為了驗證對未使用是以你的額兩個查詢再次進行校驗:
select count(*) from part_tab where c3 > date '1995-01-01' and c3 < date
'1996-12-31' and c2='hello';
#0.291s
select count(*) from no_part_tab where c3 > date '1995-01-01' and c3 < date '1996-12-31' and c2='hello';
#查詢時間1.216s
= 初步結論 =
* 分區和未分區占用檔案空間大緻相同 (資料和索引檔案)
* 如果查詢語句中有未建立索引字段,分區時間遠遠優于未分區時間
* 如果查詢語句中字段建立了索引,分區和未分區的差别縮小,分區略優于未分區。
= 最終結論 =
* 對于大資料量,建議使用分區功能。
* 去除不必要的字段
* 根據手冊, 增加myisam_max_sort_file_size 會增加分區性能
[分區指令詳解]
= 分區例子 =
* RANGE 類型
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY RANGE (uid) (
PARTITION p0 VALUES LESS THAN (3000000)
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1 VALUES LESS THAN (6000000)
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx',
PARTITION p2 VALUES LESS THAN (9000000)
DATA DIRECTORY = '/data4/data'
INDEX DIRECTORY = '/data5/idx',
PARTITION p3 VALUES LESS THAN MAXVALUE DATA DIRECTORY = '/data6/data'
INDEX DIRECTORY = '/data7/idx'
);
在這裡,将使用者表分成4個分區,以每300萬條記錄為界限,每個分區都有自己獨立的資料、索引檔案的存放目錄,與此同時,這些目錄所在的實體磁盤分區可能也都是完全獨立的,可以提高磁盤IO吞吐量。
* LIST 類型
CREATE TABLE category (
cid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY LIST (cid) (
PARTITION p0 VALUES IN (0,4,8,12)
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1 VALUES IN (1,5,9,13)
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx',
PARTITION p2 VALUES IN (2,6,10,14)
DATA DIRECTORY = '/data4/data'
INDEX DIRECTORY = '/data5/idx',
PARTITION p3 VALUES IN (3,7,11,15)
DATA DIRECTORY = '/data6/data'
INDEX DIRECTORY = '/data7/idx'
);
分成4個區,資料檔案和索引檔案單獨存放。
* HASH 類型
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY HASH (uid) PARTITIONS 4 (
PARTITION p0
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx',
PARTITION p2
DATA DIRECTORY = '/data4/data'
INDEX DIRECTORY = '/data5/idx',
PARTITION p3
DATA DIRECTORY = '/data6/data'
INDEX DIRECTORY = '/data7/idx'
);
分成4個區,資料檔案和索引檔案單獨存放。
例子:
CREATE TABLE ti2 (id INT, amount DECIMAL(7,2), tr_date DATE)
ENGINE=myisam
PARTITION BY HASH( MONTH(tr_date) )
PARTITIONS 6;
CREATE PROCEDURE load_ti2()
begin
declare v int default 0;
while v < 80000
do
insert into ti2
values (v,'3.14',adddate('1995-01-01',(rand(v)*3652) mod 365));
set v = v + 1;
end while;
end
//
* KEY 類型
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY KEY (uid) PARTITIONS 4 (
PARTITION p0
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx',
PARTITION p2
DATA DIRECTORY = '/data4/data'
INDEX DIRECTORY = '/data5/idx',
PARTITION p3
DATA DIRECTORY = '/data6/data'
INDEX DIRECTORY = '/data7/idx'
);
分成4個區,資料檔案和索引檔案單獨存放。
* 子分區
子分區是針對 RANGE/LIST 類型的分區表中每個分區的再次分割。再次分割可以是 HASH/KEY 等類型。例如:
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY RANGE (uid) SUBPARTITION BY HASH (uid % 4) SUBPARTITIONS 2(
PARTITION p0 VALUES LESS THAN (3000000)
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1 VALUES LESS THAN (6000000)
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx'
);
對 RANGE 分區再次進行子分區劃分,子分區采用 HASH 類型。
或者
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY RANGE (uid) SUBPARTITION BY KEY(uid) SUBPARTITIONS 2(
PARTITION p0 VALUES LESS THAN (3000000)
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1 VALUES LESS THAN (6000000)
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx'
);
對 RANGE 分區再次進行子分區劃分,子分區采用 KEY 類型。
= 分區管理 =
* 删除分區
ALERT TABLE users DROP PARTITION p0;
删除分區 p0。
* 重建分區
o RANGE 分區重建
ALTER TABLE users REORGANIZE PARTITION p0,p1 INTO (PARTITION p0 VALUES LESS THAN (6000000));
将原來的 p0,p1 分區合并起來,放到新的 p0 分區中。
o LIST 分區重建
ALTER TABLE users REORGANIZE PARTITION p0,p1 INTO (PARTITION p0 VALUES IN(0,1,4,5,8,9,12,13));
将原來的 p0,p1 分區合并起來,放到新的 p0 分區中。
o HASH/KEY 分區重建
ALTER TABLE users REORGANIZE PARTITION COALESCE PARTITION 2;
用 REORGANIZE 方式重建分區的數量變成2,在這裡數量隻能減少不能增加。想要增加可以用 ADD PARTITION 方法。
* 新增分區
o 新增 RANGE 分區
ALTER TABLE category ADD PARTITION (PARTITION p4 VALUES IN (16,17,18,19)
DATA DIRECTORY = '/data8/data'
INDEX DIRECTORY = '/data9/idx');
新增一個RANGE分區。
o 新增 HASH/KEY 分區
ALTER TABLE users ADD PARTITION PARTITIONS 8;
将分區總數擴充到8個。
[ 給已有的表加上分區 ]
alter table results partition by RANGE (month(ttime))
(PARTITION p0 VALUES LESS THAN (1),
PARTITION p1 VALUES LESS THAN (2) , PARTITION p2 VALUES LESS THAN (3) ,
PARTITION p3 VALUES LESS THAN (4) , PARTITION p4 VALUES LESS THAN (5) ,
PARTITION p5 VALUES LESS THAN (6) , PARTITION p6 VALUES LESS THAN (7) ,
PARTITION p7 VALUES LESS THAN (8) , PARTITION p8 VALUES LESS THAN (9) ,
PARTITION p9 VALUES LESS THAN (10) , PARTITION p10 VALUES LESS THAN (11),
PARTITION p11 VALUES LESS THAN (12),
PARTITION P12 VALUES LESS THAN (13) );
預設分區限制分區字段必須是主鍵(PRIMARY KEY)的一部分,為了去除此
限制:
[方法1] 使用ID
mysql> ALTER TABLE np_pk
-> PARTITION BY HASH( TO_DAYS(added) )
-> PARTITIONS 4;
ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function
However, this statement using the id column for the partitioning column is valid, as shown here:
mysql> ALTER TABLE np_pk
-> PARTITION BY HASH(id)
-> PARTITIONS 4;
Query OK, 0 rows affected (0.11 sec)
Records: 0 Duplicates: 0 Warnings: 0
[方法2] 将原有PK去掉生成新PK
mysql> alter table results drop PRIMARY KEY;
Query OK, 5374850 rows affected (7 min 4.05 sec)
Records: 5374850 Duplicates: 0 Warnings: 0
mysql> alter table results add PRIMARY KEY(id, ttime);
Query OK, 5374850 rows affected (6 min 14.86 sec)
Records: 5374850 Duplicates: 0 Warnings: 0
轉自https://blog.csdn.net/tjcyjd/article/details/11194489