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CREATE TABLE ti (id INT, amount DECIMAL(7,2), tr_date DATE) ENGINE=INNODB PARTITION BY HASH( MONTH(tr_date) ) PARTITIONS 6; 

Each PARTITION  clause can include a [STORAGE] ENGINE  option, but in MySQL 8.0 this has no effect. 

Unless otherwise specified, the remaining examples in this discussion assume that default_storage_engine  is InnoDB . 

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## Important 

Partitioning applies to all data and indexes of a table; you cannot partition only the data and not the indexes, or vice versa, nor can you partition only a portion of the table. 

Data and indexes for each partition can be assigned to a specific directory using the DATA DIRECTORY and INDEX DIRECTORY  options for the PARTITION  clause of the CREATE TABLE  statement used to create the partitioned table. 

Only the DATA DIRECTORY  option is supported for individual partitions and subpartitions of InnoDB tables. As of MySQL 8.0.21, the directory specified in a DATA DIRECTORY  clause must be known to InnoDB . For more information, see Using the DATA DIRECTORY Clause. 

All columns used in the table’s partitioning expression must be part of every unique key that the table may have, including any primary key. This means that a table such as this one, created by the following SQL statement, cannot be partitioned: 

CREATE TABLE tnp ( id INT NOT NULL AUTO_INCREMENT, ref BIGINT NOT NULL, name VARCHAR(255), PRIMARY KEY pk (id), UNIQUE KEY uk (name) ); 

Because the keys pk  and uk  have no columns in common, there are no columns available for use in a partitioning expression. Possible workarounds in this situation include adding the name  column to the table’s primary key, adding the id  column to uk , or simply removing the unique key altogether. See Section 24.6.1, “Partitioning Keys, Primary Keys, and Unique Keys” , for more information. 

In addition, MAX_ROWS  and MIN_ROWS  can be used to determine the maximum and minimum numbers of rows, respectively, that can be stored in each partition. See Section 24.3, “Partition Management” , for more information on these options. 

The MAX_ROWS  option can also be useful for creating NDB Cluster tables with extra partitions, thus allowing for greater storage of hash indexes. See the documentation for the DataMemory  data node configuration parameter, as well as Section 23.1.2, “NDB Cluster Nodes, Node Groups, Fragment Replicas, and Partitions” , for more information. 

Some advantages of partitioning are listed here: 

•Partitioning makes it possible to store more data in one table than can be held on a single disk or file system partition. 

•Data that loses its usefulness can often be easily removed from a partitioned table by dropping the partition (or partitions) containing only that data. Conversely, the process of adding new data can in some cases be greatly facilitated by adding one or more new partitions for storing specifically that data. 

