Partitioning Basics

Oracle allows to divide table and index data into a smaller parts - partitions and sub-partitions that can be stored and managed individually. dbForge Studio provides you handy interface for creating partitioned tables, and manipulating partitions and sub-partitions.

Note

Clustered tables and tables containing any LONG or LONG RAW columns cannot be partitioned.

Oracle provides you several partitioning methods. They are range, hash and list partitioning and composite partitioning. Range partitioning provides mapping rows to partitions based on ranges of column values. Hash partitioning provides mapping rows to partitions based on a hash value of partitioning key. List partitioning provides mapping rows to partitions based on lists of discrete values set for each partitions. When using composite partitioning method table is divided into partitions using range partitioning method and partitions can be further divided into sub-partitions with hash or list subpartitioning method.

The partitioning key is a set of one or more table columns that determines the partition. It can contain from one to 16 columns. When using list partitioning method, partitioning key can contain only one column.

Note

Index-organized tables cannot be partitioned with composite partitioning method. Index-organized tables can be partitioned with list partitioning method only on Oracle 10g and higher. Partitioning key of index-organized table must be a subset of table’s primary key columns.