Logical Structures Flashcards
What are the logical structures from smallest to largest?
- Data Blocks
- Extents
- Segments
- Tablespaces
What are Data Blocks?
The smallest units of storage that Oracle can use or allocate
One data block corresponds to a specific number of bytes of physical database space on disk
What are Extents?
A collection of contiguous data blocks
Provided by the system during a single allocation
What are Segments?
A set of extents that have been allocated for a specific type of data structure
Used to store a single database object
What are Tablespaces?
Comprised of one or more operating system files called datafiles.
What is ROWID?
A a pseudocolumn that uniquely defines a single row in a database table
What is ROWID associated with?
A table row when the row is created
In ROWID AABMjXAAEAAAGwTAAA
What does ‘AABMjX’ represent’?
The data object number
In ROWID AABMjXAAEAAAGwTAAA
What does ‘AAE’ represent’?
The data file number that the row is in
In ROWID AABMjXAAEAAAGwTAAA
What does ‘AAAGwT’ represent’?
The data block number that the row is in
In ROWID AABMjXAAEAAAGwTAAA
What does ‘AAA’ represent’?
The row number within the data block
