MySQL 表分区（六）

•  子表分区，是在表分区的基础上再创建表分区的概念，每个表分区下的子表分区个数必须一致

mysql> CREATE TABLE ts (id INT, purchased DATE)
    -> PARTITION BY RANGE( YEAR(purchased) )
    -> SUBPARTITION BY HASH( TO_DAYS(purchased) )
    -> SUBPARTITIONS 2
    -> ( PARTITION p0 VALUES LESS THAN (1990),
    -> PARTITION p1 VALUES LESS THAN (2000),
    -> PARTITION p2 VALUES LESS THAN MAXVALUE );
Query OK, 0 rows affected (0.48 sec)

mysql> desc information_schema.partitions;
+-------------------------------+---------------------+------+-----+---------+-------+
| Field                         | Type                | Null | Key | Default | Extra |
+-------------------------------+---------------------+------+-----+---------+-------+
| TABLE_CATALOG                 | varchar(64)         | NO   |     | NULL    |       |
| TABLE_SCHEMA                  | varchar(64)         | NO   |     | NULL    |       |
| TABLE_NAME                    | varchar(64)         | NO   |     | NULL    |       |
| PARTITION_NAME                | varchar(64)         | YES  |     | NULL    |       |
| SUBPARTITION_NAME             | varchar(64)         | YES  |     | NULL    |       |
| PARTITION_ORDINAL_POSITION    | int(6) unsigned     | YES  |     | NULL    |       |
| SUBPARTITION_ORDINAL_POSITION | int(6) unsigned     | YES  |     | NULL    |       |
| PARTITION_METHOD              | varchar(13)         | YES  |     | NULL    |       |
| SUBPARTITION_METHOD           | varchar(13)         | YES  |     | NULL    |       |
| PARTITION_EXPRESSION          | varchar(2048)       | YES  |     | NULL    |       |
| SUBPARTITION_EXPRESSION       | varchar(2048)       | YES  |     | NULL    |       |
| PARTITION_DESCRIPTION         | text                | YES  |     | NULL    |       |
| TABLE_ROWS                    | bigint(21) unsigned | YES  |     | NULL    |       |
| AVG_ROW_LENGTH                | bigint(21) unsigned | YES  |     | NULL    |       |
| DATA_LENGTH                   | bigint(21) unsigned | YES  |     | NULL    |       |
| MAX_DATA_LENGTH               | bigint(21) unsigned | YES  |     | NULL    |       |
| INDEX_LENGTH                  | bigint(21) unsigned | YES  |     | NULL    |       |
| DATA_FREE                     | bigint(21) unsigned | YES  |     | NULL    |       |
| CREATE_TIME                   | timestamp           | NO   |     | NULL    |       |
| UPDATE_TIME                   | datetime            | YES  |     | NULL    |       |
| CHECK_TIME                    | datetime            | YES  |     | NULL    |       |
| CHECKSUM                      | bigint(21)          | YES  |     | NULL    |       |
| PARTITION_COMMENT             | text                | NO   |     | NULL    |       |
| NODEGROUP                     | varchar(256)        | YES  |     | NULL    |       |
| TABLESPACE_NAME               | varchar(259)        | YES  |     | NULL    |       |
+-------------------------------+---------------------+------+-----+---------+-------+
25 rows in set (0.01 sec)

mysql> select partition_name,subpartition_name from information_schema.partitions where table_name='ts';
+----------------+-------------------+
| PARTITION_NAME | SUBPARTITION_NAME |
+----------------+-------------------+
| p0             | p0sp0             |
| p0             | p0sp1             |
| p1             | p1sp0             |
| p1             | p1sp1             |
| p2             | p2sp0             |
| p2             | p2sp1             |
+----------------+-------------------+
6 rows in set (0.00 sec)

mysql> select to_days(now());
+----------------+
| to_days(now()) |
+----------------+
|         737917 |
+----------------+
1 row in set (0.00 sec)

mysql> desc ts;
+-----------+---------+------+-----+---------+-------+
| Field     | Type    | Null | Key | Default | Extra |
+-----------+---------+------+-----+---------+-------+
| id        | int(11) | YES  |     | NULL    |       |
| purchased | date    | YES  |     | NULL    |       |
+-----------+---------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> insert into ts values(1,now());
Query OK, 1 row affected, 1 warning (0.10 sec)

mysql> insert into ts values(1,'1980-01-01');
Query OK, 1 row affected (0.09 sec)

mysql> select * from ts partition(p1);
Empty set (0.00 sec)

mysql> select * from ts partition(p2);
+------+------------+
| id   | purchased  |
+------+------------+
|    1 | 2020-05-07 |
+------+------------+
1 row in set (0.00 sec)

mysql> select * from ts partition(p0sp0);
+------+------------+
| id   | purchased  |
+------+------------+
|    1 | 1980-01-01 |
+------+------------+
1 row in set (0.00 sec)

mysql> select * from ts partition(p0sp1);
Empty set (0.00 sec)

mysql> select purchased,to_days(purchased) from ts;
+------------+--------------------+
| purchased  | to_days(purchased) |
+------------+--------------------+
| 1980-01-01 |             723180 |
| 2020-05-07 |             737917 |
+------------+--------------------+
2 rows in set (0.00 sec)

mysql> select * from ts partition(p2sp0);
Empty set (0.00 sec)

mysql> select * from ts partition(p2sp0);
Empty set (0.00 sec)

mysql> select * from ts partition(p2);
+------+------------+
| id   | purchased  |
+------+------------+
|    1 | 2020-05-07 |
+------+------------+
1 row in set (0.00 sec)

mysql> explain select * from ts where purchased='2020-05-07';
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | ts    | p2_p2sp1   | ALL  | NULL          | NULL | NULL    | NULL |    1 |   100.00 | Using where |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+
1 row in set, 1 warning (0.00 sec)

mysql> CREATE TABLE t1 ( c1 INT, c2 VARCHAR(20) )
    -> PARTITION BY RANGE(c1)
    -> ( PARTITION p0 VALUES LESS THAN (0),
    -> PARTITION p1 VALUES LESS THAN (10),
    -> PARTITION p2 VALUES LESS THAN MAXVALUE );
Query OK, 0 rows affected (0.18 sec)

mysql> select * from t1;
Empty set (0.01 sec)

mysql> insert into ti values(-1,'a');
ERROR 1146 (42S02): Table 'course.ti' doesn't exist
mysql> insert into t1 values(-1,'a');
Query OK, 1 row affected (0.05 sec)

mysql> select * from t1 partition(p0);
+------+------+
| c1   | c2   |
+------+------+
|   -1 | a    |
+------+------+
1 row in set (0.01 sec)

mysql> insert into t1 values(null,'b');
Query OK, 1 row affected (0.04 sec)

mysql> select * from t1;
+------+------+
| c1   | c2   |
+------+------+
|   -1 | a    |
| NULL | b    |
+------+------+
2 rows in set (0.00 sec)

mysql> select * from t1 partition(p0);
+------+------+
| c1   | c2   |
+------+------+
|   -1 | a    |
| NULL | b    |
+------+------+
2 rows in set (0.00 sec)

mysql> select * from t1 partition(p2);
Empty set (0.01 sec)

mysql> CREATE TABLE ts1 (c1 INT, c2 VARCHAR(20))
    -> PARTITION BY LIST(c1)
    -> (PARTITION p0 VALUES IN (0, 3, 6), 
    -> PARTITION p1 VALUES IN (1, 4, 7), 
    -> PARTITION p2 VALUES IN (2, 5, 8));
Query OK, 0 rows affected (0.26 sec)

mysql> insert into ts1 values(null,'a');
ERROR 1526 (HY000): Table has no partition for value NULL
mysql> insert into ts1 values(10,'a');
ERROR 1526 (HY000): Table has no partition for value 10
mysql> 
mysql> 
mysql> drop table ts1;
Query OK, 0 rows affected (0.09 sec)

mysql> CREATE TABLE ts1 (c1 INT, c2 VARCHAR(20))
    -> PARTITION BY LIST(c1)
    -> (PARTITION p0 VALUES IN (0, 3, 6), 
    -> PARTITION p1 VALUES IN (1, 4, 7,null), 
    -> PARTITION p2 VALUES IN (2, 5, 8));
Query OK, 0 rows affected (0.13 sec)

mysql> insert into ts1 values(null,'a');
Query OK, 1 row affected (0.07 sec)

mysql> select * from ts1 partition(p1);
+------+------+
| c1   | c2   |
+------+------+
| NULL | a    |
+------+------+
1 row in set (0.00 sec)

mysql> CREATE TABLE th ( c1 INT, c2 VARCHAR(20) )
    -> PARTITION BY HASH(c1)
    -> PARTITIONS 2;
Query OK, 0 rows affected (0.18 sec)

mysql> insert into th values(null,'a');
Query OK, 1 row affected (0.01 sec)

mysql> select * from th;
+------+------+
| c1   | c2   |
+------+------+
| NULL | a    |
+------+------+
1 row in set (0.00 sec)

mysql> select * from th partition(p1);
Empty set (0.00 sec)