Data storage
The database server uses physical units of storage to allocate disk space. It stores data in logical units. Unlike the logical units of storage whose size fluctuates, each of the physical units has a fixed or assigned size that is determined by the disk architecture.
The following topics define terms and explain concepts that you must understand to manage disk space. These topics cover the following areas:
- Definitions of the physical and logical units that the database server uses to store data on disk
- Instructions on how to calculate the amount of disk space that you require to store your data
- Guidelines on how to lay out your disk space and where to place your databases and tables
- Instructions on using external tables
- The database server uses the following physical units to manage disk space:
- Chunks
- Pages
- Blobpages
- Sbpages
- Extents
- The database server stores data in the following logical units:
- Dbspaces
- Temporary dbspaces
- Blobspaces
- Sbspaces
- Temporary sbspaces
- Plogspace
- Extspaces
- Databases
- Tables
- Tblspaces
- Partitions and offsets
- The database server maintains the following storage structures to ensure physical and logical consistency of data:
- Logical log
- Physical log
- Reserved pages