os: centos 7.4.1708
db: mysql 8.0.20
版本
# cat /etc/centos-release
CentOS Linux release 7.4.1708 (Core)
#
#
# yum list installed |grep -i mysql80
mysql-community-client.x86_64 8.0.20-1.el7 @mysql80-community
mysql-community-common.x86_64 8.0.20-1.el7 @mysql80-community
mysql-community-devel.x86_64 8.0.20-1.el7 @mysql80-community
mysql-community-libs.x86_64 8.0.20-1.el7 @mysql80-community
mysql-community-libs-compat.x86_64 8.0.20-1.el7 @mysql80-community
mysql-community-server.x86_64 8.0.20-1.el7 @mysql80-community
mysql-community-test.x86_64 8.0.20-1.el7 @mysql80-community
mysql80-community-release.noarch el7-3 installed
# mysql -e "select version();"
+-----------+
| version() |
+-----------+
| 8.0.20 |
+-----------+
partition by hash
# mysql
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.00 sec)
mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> CREATE TABLE part_hash
(
id INT NOT NULL AUTO_INCREMENT,
amount DECIMAL(7,2),
tr_date DATE,
PRIMARY KEY pk_part_hash (id,tr_date)
)
ENGINE=INNODB
PARTITION BY HASH( MONTH(tr_date) )
PARTITIONS 6;
alter table part_hash add index idx_month_tr_date ((month(tr_date)));
mysql>
mysql> select * from information_schema.tables where table_schema='test' and table_name like 'part_hash%';
+---------------+--------------+------------+------------+--------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------------+
| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | TABLE_TYPE | ENGINE | VERSION | ROW_FORMAT | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | AUTO_INCREMENT | CREATE_TIME | UPDATE_TIME | CHECK_TIME | TABLE_COLLATION | CHECKSUM | CREATE_OPTIONS | TABLE_COMMENT |
+---------------+--------------+------------+------------+--------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------------+
| def | test | part_hash | BASE TABLE | InnoDB | 10 | Dynamic | 51 | 1927 | 98304 | 0 | 98304 | 0 | 52 | 2020-07-01 15:30:40 | NULL | NULL | utf8mb4_0900_ai_ci | NULL | partitioned | |
+---------------+--------------+------------+------------+--------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------------+
1 row in set (0.00 sec)
mysql> select * from information_schema.partitions where table_schema='test' and table_name like 'part_hash%';
+---------------+--------------+------------+----------------+-------------------+----------------------------+-------------------------------+------------------+---------------------+----------------------+-------------------------+-----------------------+------------+----------------+-------------+-----------------+--------------+-----------+---------------------+-------------+------------+----------+-------------------+-----------+-----------------+
| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | PARTITION_NAME | SUBPARTITION_NAME | PARTITION_ORDINAL_POSITION | SUBPARTITION_ORDINAL_POSITION | PARTITION_METHOD | SUBPARTITION_METHOD | PARTITION_EXPRESSION | SUBPARTITION_EXPRESSION | PARTITION_DESCRIPTION | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | CREATE_TIME | UPDATE_TIME | CHECK_TIME | CHECKSUM | PARTITION_COMMENT | NODEGROUP | TABLESPACE_NAME |
+---------------+--------------+------------+----------------+-------------------+----------------------------+-------------------------------+------------------+---------------------+----------------------+-------------------------+-----------------------+------------+----------------+-------------+-----------------+--------------+-----------+---------------------+-------------+------------+----------+-------------------+-----------+-----------------+
| def | test | part_hash | p0 | NULL | 1 | NULL | HASH | NULL | month(`tr_date`) | NULL | NULL | 30 | 546 | 16384 | 0 | 16384 | 0 | 2020-07-01 15:30:40 | NULL | NULL | NULL | | default | NULL |
| def | test | part_hash | p1 | NULL | 2 | NULL | HASH | NULL | month(`tr_date`) | NULL | NULL | 0 | 0 | 16384 | 0 | 16384 | 0 | 2020-07-01 15:30:40 | NULL | NULL | NULL | | default | NULL |
| def | test | part_hash | p2 | NULL | 3 | NULL | HASH | NULL | month(`tr_date`) | NULL | NULL | 0 | 0 | 16384 | 0 | 16384 | 0 | 2020-07-01 15:30:40 | NULL | NULL | NULL | | default | NULL |
| def | test | part_hash | p3 | NULL | 4 | NULL | HASH | NULL | month(`tr_date`) | NULL | NULL | 0 | 0 | 16384 | 0 | 16384 | 0 | 2020-07-01 15:30:40 | NULL | NULL | NULL | | default | NULL |
| def | test | part_hash | p4 | NULL | 5 | NULL | HASH | NULL | month(`tr_date`) | NULL | NULL | 0 | 0 | 16384 | 0 | 16384 | 0 | 2020-07-01 15:30:40 | NULL | NULL | NULL | | default | NULL |
| def | test | part_hash | p5 | NULL | 6 | NULL | HASH | NULL | month(`tr_date`) | NULL | NULL | 21 | 780 | 16384 | 0 | 16384 | 0 | 2020-07-01 15:30:40 | NULL | NULL | NULL | | default | NULL |
+---------------+--------------+------------+----------------+-------------------+----------------------------+-------------------------------+------------------+---------------------+----------------------+-------------------------+-----------------------+------------+----------------+-------------+-----------------+--------------+-----------+---------------------+-------------+------------+----------+-------------------+-----------+-----------------+
6 rows in set (0.00 sec)
mysql> select * from information_schema.innodb_tables where name like '%part_hash%';
+----------+---------------------+------+--------+-------+------------+---------------+------------+--------------+
| TABLE_ID | NAME | FLAG | N_COLS | SPACE | ROW_FORMAT | ZIP_PAGE_SIZE | SPACE_TYPE | INSTANT_COLS |
+----------+---------------------+------+--------+-------+------------+---------------+------------+--------------+
| 1190 | test/part_hash#p#p0 | 33 | 6 | 42 | Dynamic | 0 | Single | 0 |
| 1191 | test/part_hash#p#p1 | 33 | 6 | 43 | Dynamic | 0 | Single | 0 |
| 1192 | test/part_hash#p#p2 | 33 | 6 | 44 | Dynamic | 0 | Single | 0 |
| 1193 | test/part_hash#p#p3 | 33 | 6 | 45 | Dynamic | 0 | Single | 0 |
| 1194 | test/part_hash#p#p4 | 33 | 6 | 46 | Dynamic | 0 | Single | 0 |
| 1195 | test/part_hash#p#p5 | 33 | 6 | 47 | Dynamic | 0 | Single | 0 |
+----------+---------------------+------+--------+-------+------------+---------------+------------+--------------+
6 rows in set (0.01 sec)
mysql> show create table part_hash;
+-----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| part_hash | CREATE TABLE `part_hash` (
`id` int NOT NULL AUTO_INCREMENT,
`amount` decimal(7,2) DEFAULT NULL,
`tr_date` date NOT NULL,
PRIMARY KEY (`id`,`tr_date`),
KEY `idx_month_tr_date` ((month(`tr_date`)))
) ENGINE=InnoDB AUTO_INCREMENT=52 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
/*!50100 PARTITION BY HASH (month(`tr_date`))
PARTITIONS 6 */ |
+-----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
/!../ 是一種特殊的註釋，其他的數據庫產品不會執行。mysql特殊處理，會選擇性的執行。可以認爲是：預編譯中的條件編譯。
特別注意 50100，它表示5.01.00 版本或者更高的版本，才執行。
# ls -l /var/lib/mysql/test
total 786432
-rw-r----- 1 mysql mysql 131072 Jul 1 15:30 part_hash#p#p0.ibd
-rw-r----- 1 mysql mysql 131072 Jul 1 15:30 part_hash#p#p1.ibd
-rw-r----- 1 mysql mysql 131072 Jul 1 15:30 part_hash#p#p2.ibd
-rw-r----- 1 mysql mysql 131072 Jul 1 15:30 part_hash#p#p3.ibd
-rw-r----- 1 mysql mysql 131072 Jul 1 15:30 part_hash#p#p4.ibd
-rw-r----- 1 mysql mysql 131072 Jul 1 15:30 part_hash#p#p5.ibd
mysql> call generate_seed(50,100);
mysql> insert into part_hash(amount,tr_date)
select @a := @a +1, date_sub(current_date(), interval @a day)
from generate_seed_tmp,(select @a:=0) as seq
;
mysql> select * from part_hash;
+----+--------+------------+
| id | amount | tr_date |
+----+--------+------------+
| 1 | 1.00 | 2020-06-30 |
| 2 | 2.00 | 2020-06-29 |
| 3 | 3.00 | 2020-06-28 |
| 4 | 4.00 | 2020-06-27 |
| 5 | 5.00 | 2020-06-26 |
···
···
···
| 47 | 47.00 | 2020-05-15 |
| 48 | 48.00 | 2020-05-14 |
| 49 | 49.00 | 2020-05-13 |
| 50 | 50.00 | 2020-05-12 |
| 51 | 51.00 | 2020-05-11 |
+----+--------+------------+
51 rows in set (0.00 sec)
mysql> explain select * from part_hash where MONTH(tr_date)=5;
+----+-------------+-----------+-------------------+------+-------------------+-------------------+---------+-------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-----------+-------------------+------+-------------------+-------------------+---------+-------+------+----------+-------+
| 1 | SIMPLE | part_hash | p0,p1,p2,p3,p4,p5 | ref | idx_month_tr_date | idx_month_tr_date | 5 | const | 21 | 100.00 | NULL |
+----+-------------+-----------+-------------------+------+-------------------+-------------------+---------+-------+------+----------+-------+
1 row in set, 1 warning (0.00 sec)
注意看執行計劃的 partitions 列爲 p0,p1,p2,p3,p4,p5
參考:
https://dev.mysql.com/doc/refman/8.0/en/partitioning.html
https://dev.mysql.com/doc/refman/8.0/en/partitioning-types.html
https://dev.mysql.com/doc/refman/8.0/en/create-table.html