Oracle Author: Anonymous Source: InterNet Add Time: 2003-7-20 a tablespace can only belong to one database
At least one control file per database (recommended 3, on separate disks)
At least one table space per database (System tablespace)
The purpose of the system table space is to keep tables together as much as possible to improve efficiency, and only data dictionaries should be stored.
There are at least two online log groups per database, with at least one online log file per group
A data file can belong to only one table space
Once a data file is added to a table space, it can no longer be removed from the tablespace and can no longer be added to other table spaces.
Creating a new table space requires a new data file
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.
And the future can not change, to change, only to rebuild the database
A segment segment can belong to only one table space, but may belong to multiple data files
A zone extent can only belong to one data file, that is, the interval (extent) cannot cross the data file
Pctfree and pctused sum cannot be greater than or equal to 100
A single transaction cannot span multiple rollback segments
Index table does not contain ROWID value
There is no benefit to having a rollback segment of different sizes
After a commit, the data does not necessarily write the disk immediately (data file)
A transaction is written to the redo log even if it is not committed.
In Oracle 8.0.4, the default database that was established at the initial installation, with the instance named ORCL
The maximum length of a block is 16KB (with 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
Oracle server can start multiple databases at the same time
Multiple versions of Oracle database systems can be installed on a set of operating systems (Unix can, NT not)
A set of Oracle database systems can have multiple Oracle databases and their corresponding instances
Each Oracle database has one database instance (INSTANCE) (excluding OPS)
So, a set of operating systems can have multiple Oracle database instances to start at the same time
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