Memory Architecture   «Prev 

SGA Components

System Global Area


  1. Database Buffer Cache: Holds data blocks read from disk
  2. Keep Buffer Pool: Data blocks that are kept in memory
  3. Recycle Buffer Pool: Data blocks that are recycled as soon as possible
  4. Default Buffer Pool: Data blocks managed in the default fashion
  5. Redo Log Buffer: Holds redo log entries waiting to be written to disk
  6. Fixed SGA: Contains general information about the state of the database and the instance
  7. Large Pool: An optional memory area used for backup and restore operations
  8. Shared Pool: Contains memory structures related to SQL execution
  9. Library Cache: Contains the shared SQL area and PL/SQL code
  10. Data Dictionary Cache: An area in the Shared Pool where Oracle stores frequently accessed data dictionary information so that it does not need to be continuously reread from disk
  11. Control Structures: Library cache: Locks, cache handles, etc.
  12. Control Structures: Shared pool: character set conversion memory, etc.
  13. Shared SQL Area: SQL statements and execution plans
  14. PL/SQL Code: packages, procedures, and functions