Virtual columns enable the partitioning key to be defined by an expression, using one or more existing columns of a table. The expression is stored as metadata only.
Oracle Partitioning has been enhanced to enable a partitioning strategy to be defined on virtual columns. For example, a 10-digit account ID can include account branch information as the leading three digits. With the extension of virtual column based partitioning, an ACCOUNTS table containing an ACCOUNT_ID column can be extended with a virtual (derived) column ACCOUNT_BRANCH. ACCOUNT_BRANCH is derived from the first three digits of the ACCOUNT_ID column, which becomes the partitioning key for this table.
Virtual column-based partitioning is supported with all basic partitioning strategies, including reference partitioning, and interval and interval-* composite partitioning.