From: PConline
1. One tablespace can only belong to a database.
2. Each database has a minimum of one control file (suggests 3, which are placed on different disks).
3. Each database has a table space (System table space).
4. The purpose of establishing the SYSTEM table space is to allow the same table as possible to increase the use efficiency and should only store data dictionary.
5. Each database has a minimum of two online log groups, with a minimum of one online log file.
6. A data file can only belong to a table space.
7. Once a data file is added to a table space, it is no longer removed from this table space, and can no longer be added to other tablespaces.
8. Establish a new table space to create a new data file.
9. Data file is formatted by Oracle to Oracle block, in previous versions of Oracle9i, the size of the Oracle block is set when the database is created for the first time.
10. And you can't change in the future, you want to change, you can only rebuild the database.
11. A segment segment can only belong to a table space, but can belong to multiple data files.
12. A zone extent can only belong to a data file, that is, intervals cannot span data files.
13. PctFree and Pctused sums cannot be greater than or equal to 100.
14. A single transaction cannot span multiple rollback segments.
15. The index table does not contain the ROWID value.
16. There is no benefit of returning a rollback segment with different sizes.
17.Commit, the data is not necessarily written immediately (data files).
18. Even if it is not submitted, it will be written to the redo log.
19. ORACLE 8.0.4, the default database established during initial installation, instance is named ORCL.
20. The maximum length of one block is 16KB (2K, 4K, 8K, 16K).
The maximum number of files per database (by block size)
2K block 2000 files
4K block 40000 files
8K block or more 65536 files
21. Oracle Server can start multiple databases at the same time.
22. A plurality of versions of Oracle database systems (UNIX can, NT can be installed on a set of operating systems.
23. A set of Oracle database systems can have multiple Oracle databases and their corresponding instances.
24. Each Oracle Database has a database instance (except for OPS).
25. So, a set of operating systems can have multiple Oracle database instances to start.
