OceanBase Database can split the data of a table into different groups based on some rules. Data in the same group is stored in the same physical area. This area is called a partition. A table split in this way is called a partitioned table.
For example, the following figure shows a table that consists of five partitions, which are distributed across two nodes.
Each partition can be divided into subpartitions based on some rules. A table that contains both partitions and subpartitions is called a subpartitioned table.
In a table row, a column determines which partition the row belongs to. The set of data in this column is called the partitioning key. The partitioning key must be a subset of a primary key or a unique key. An expression contains the partitioning key and determines which partitions the rows belong to. This expression is called a partitioning expression.