Cold partitions make use of Paged Attributes. While ordinary columns are loaded entirely into memory upon first access, Paged Attributes are loaded page-wise. Ideally only the pages that hold the requested rows are being loaded.
In the context of data aging/cold partitions there are only a few (release dependend) constraints which columns cannot be paged:
- Some data types (LOB, BLOB, CLOB, TEXT, GEOMETRY, POINT)
- Some internal columns ($RowID$, $Udiv$, Shadow columns for text indexes)