Advanced MySQL 8

KEY partitioning

KEY partitioning in quite like partitioning by HASH. This difference is that only one or more columns are provided for evaluation, and the HASH function is supplied by MySQL.

Using KEY is like CREATE TABLE ... PARTITION BY KEY and is similar to creating a table partitioned with HASH. The following are the main differences:

• KEY will be used rather than HASH
• Only lists of zero of more column names are accepted by KEY
• If the table has a primary key, some or all of it must be contained in columns used as a partitioning key
• If no column name is specified as the partitioning key, the primary key of the table is used as the default

Let's try the following example:

If NOT NULL was not specified in the unique key column, this command ...