2. Each database has at least one control file (recommendation 3, placed on separate disks).
3. Each database has at least one table space (System tablespace).
4. The purpose of establishing the system table space is to keep tables of the same purpose as possible so as to improve the efficiency of the use of the data dictionary.
5. Each database has at least two online log groups, with at least one online log file per group.
6. A data file can only belong to one table space.
7. Once a data file is added to a table space, it can no longer be removed from the table space and can no longer be added to other tablespace spaces.
8. The creation of new table spaces requires the creation of new data files.
9. Data files are formatted as Oracle blocks by Oracle, oracle9i in previous versions, the size of the Oracle block was set when the database was first created.
10. And the future can not change, to change, can only rebuild the database.
11. A segment segment can belong to only one table space, but may belong to multiple data files.
12. A zone extent can only belong to one data file, that is, the interval (extent) cannot cross the data file.
The sum of 13.PCTFREE and pctused cannot be greater than or equal to 100.
14. A single transaction cannot span multiple rollback segments.
15. The index table does not contain ROWID values.
16. There is no benefit to having a rollback segment of different sizes.
After 17.COMMIT, the data does not necessarily write the disk immediately (data file).
18. A transaction is written to the redo log even if it is not committed.
In 19.Oracle 8.0.4, the default database established at the initial installation, with the instance named ORCL.
20. The maximum length of a block is 16KB (2K, 4K, 8K, 16K).
Maximum number of files per database (by block size)
2 K block 20,000 files
4K Block 40,000 files
8K block or above 65,536 files
21.oracle server can start multiple databases at the same time.
22. Multiple Versions of Oracle database systems can be installed on a set of operating systems (Unix can, NT not).
23. A set of Oracle database systems can have multiple Oracle databases and their corresponding instances.
24. Each Oracle database has one database instance (INSTANCE) (excluding OPS).
25. So, a set of operating systems can also have multiple Oracle database instances to start
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