1.分区键必须包含在主键中
2.如有唯一索引，分区键必须包含在唯一索引中

CREATE TABLE `partition_test` (
`id` VARCHAR (30) NOT NULL,
`name` VARCHAR (255) DEFAULT NULL,
`create_time` datetime NOT NULL,
PRIMARY KEY (`id`, `create_time`)
) ENGINE = INNODB DEFAULT CHARSET = utf8 
PARTITION BY RANGE (TO_DAYS(create_time))(
	PARTITION p20190101
	VALUES
		LESS THAN (TO_DAYS('2019-01-01')) ENGINE = INNODB,
		PARTITION p20200101
	VALUES
		LESS THAN (TO_DAYS('2020-01-01')) ENGINE = INNODB,
		PARTITION p20210101
	VALUES
		LESS THAN (TO_DAYS('2021-01-01')) ENGINE = INNODB
);

1、create_time必须是主键
2、如对p20210101赋值less than maxvalue。有MAXVALUE值后，后续加分区是不可行的
3、分区只能在最后新增，即必须大于p20210101中的2021-01-01，不能从中间新增

select
partition_name part,
partition_expression expr,
partition_description descr,
table_rows
from information_schema.partitions where
table_schema = schema()
and table_name='partition_test';

ALTER TABLE partition_test add PARTITION (
PARTITION p4
VALUES
	LESS THAN (TO_DAYS('2021-02-01'))
);

ALTER TABLE partition_test DROP PARTITION p0

1、先创建一个新的表test1、并对改表进行分区
2、拷贝数据：insert into test1 select * from test
3、删除原表test：drop table test
4、重命名：rename table test1 to test

DELIMITER ||
-- 删除存储过程
drop procedure if exists auto_set_partitions ||
-- 注意：使用该存储过程必须保证相应数据库表中至少有一个手动分区
-- 创建存储过程[通过数据库名和对应表名]-建多少个分区，分区时间间隔为多少
-- databasename：创建分区的数据库
-- tablename：创建分区的表的名称
-- partition_number：一次创建多少个分区
-- partitiontype：分区类型[0按天分区，1按月分区，2按年分区]
-- gaps：分区间隔，如果分区类型为0则表示每个分区的间隔为 gaps天；
--       如果分区类型为1则表示每个分区的间隔为 gaps月
--            如果分区类型为2则表示每个分区的间隔为 gaps年
create procedure auto_set_partitions (in databasename varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci,in tablename varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci, in partition_number int, in partitiontype int, in gaps int)
L_END:
begin     
    declare max_partition_description varchar(255) default '';
    declare p_name varchar(255) default 0;       
    declare p_description varchar(255) default 0;   
    declare isexist_partition varchar(255) default 0; 
 declare i int default 1;
  
 -- 查看对应数据库对应表是否已经有手动分区[自动分区前提是必须有手动分区]
    select partition_name into isexist_partition from information_schema.partitions where table_schema = databasename  and table_name = tablename limit 1;
    -- 如果不存在则打印错误并退出存储过程
    if isexist_partition <=> "" then
       select "partition table not is exist" as "ERROR";
       leave L_END;
    end if;
 
    -- 获取最大[降序获取]的分区描述[值]
    select partition_description into max_partition_description  from information_schema.partitions where table_schema = databasename  and table_name = tablename order by partition_description desc limit 1;
   
    -- 如果最大分区没有,说明没有手动分区,则无法创建自动分区
    if max_partition_description <=> "" then
       select "partition table is error" as "ERROR";
       leave L_END;
    end if;
 
    -- 替换前后的单引号[''两个引号表示一个单引号的转义]
    -- set max_partition_description = REPLACE(max_partition_description, '''', '');
     -- 或使用如下语句
     set max_partition_description = REPLACE(max_partition_description-1, '\'', '');
 
   -- 自动创建number个分区
    while (i <= partition_number) do
                 if (partitiontype = 0) then
                     -- 每个分区按天递增,递增gaps天
                     set p_description = DATE_ADD(FROM_DAYS(max_partition_description), interval i*gaps day); 
                 elseif (partitiontype = 1) then
                     -- 每个分区按月递增,递增gaps月
                     set p_description = DATE_ADD(FROM_DAYS(max_partition_description), interval i*gaps month); 
                 else 
                     -- 每个分区按年递增,递增gaps年
                     set p_description = DATE_ADD(FROM_DAYS(max_partition_description), interval i*gaps year);
                 end if;
                 -- 删除空格
                 set p_name = REPLACE(p_description, ' ', '');
                 -- 例如10.20的记录实际是less than 10.21
                 set p_description = DATE_ADD(p_description, interval 1 day); 
                 -- 如果有横杆替换为空
          set p_name = REPLACE(p_name, '-', '');
                 -- 删除时间冒号
                 set p_name = REPLACE(p_name, ':', '');
                 -- alter table tablename add partition ( partition pname values less than ('2017-02-20 10:05:56') );
          set @sql=CONCAT('ALTER TABLE ', tablename ,' ADD PARTITION ( PARTITION p', p_name ,' VALUES LESS THAN (TO_DAYS(\'', p_description ,'\')))');
                 -- set @sql=CONCAT('ALTER TABLE ', tablename ,' ADD PARTITION ( PARTITION p', p_name ,' VALUES LESS THAN (TO_DAYS(\'', p_description ,'\')))');
                 -- 打印sql变量
          -- select @sql;
                 -- 准备sql语句
          PREPARE stmt from @sql;
                 -- 执行sql语句
          EXECUTE stmt;
                 -- 释放资源
          DEALLOCATE PREPARE stmt;
                 -- 递增变量
          set i = (i + 1) ;
 
    end while;          
end ||
-- 恢复语句中断符
DELIMITER ;

#每月新增一个分区、按月新增、每次新增一个月

DELIMITER ||
drop event if exists auto_set_partitions  ||
create event auto_set_partitions 
on schedule every 1 MONTH
starts '2018-10-30 00:00:00'
do
BEGIN
    call auto_set_partitions('qif', 'qif_test', 1, 1, 1);
END ||
DELIMITER ;