Logical Database structures
Logical structures include table spaces, schema objects, data blocks, extents and segments.
1.Table spaces
Database is logically divided into one or more table spaces. Each table space creates one or more data files to physically store data.
2.Schema objects
Schema objects are the structure that represents database's data. Schema objects include structures such as tables, views, sequences, stored procedures, indexes, synonyms, clusters and database links.
3.Data Blocks
Data block represents specific number of bytes of physical database space on disk.
4.Extents
An extent represents continuous data blocks that are used to store specific data information.
5.Segments
A segment is a set of extents allocated for a certain logical structure.