- Data Files and redo log files are important files in the database.
- Oracle stores data in four file systems
- Operating System (OS) File System
- Original Partition
- New Features of Automatic Storage Management (ASM) and 10g Release 1
- Cluster File System: dedicated to RAC, like the cooked file system shared by multiple nodes in the Cluster Environment
- Storage hierarchy
- A database consists of one or more tablespaces. A tablespace is a logical memory in Oracle, including one or more data files.
- A cidr block consists of one or more CIDR blocks. Segments are in the tablespace, but can contain data in multiple data files in the tablespace.
- A partition is a logical continuous block on a disk. The partition is only in one tablespace and is always in one file of the tablespace.
- A block is the smallest allocation unit in the database and the smallest I/O unit used by the database.
- Tablespace Management
- Tablespace Management Section
- Before oracle8.1.5, there was only one method: The tablespace managed by the dictionary. If an object requires another segment, it will "Apply" to the system ". Then Oracle accesses its data dictionary table, runs some queries, finds the data (maybe not), and then updates, deletes, and inserts the data.
- Temporary tablespace: You do not create your own permanent objects. The processing mode for temporary tablespace is the same as that for permanent tablespace before 7.3.
- Processing mode of temporary tablespace: Once a temporary tablespace is allocated with a partition, the system will keep holding it. The next time someone requests this temporary tablespace, Oracle will first find the allocated partition and find it for reuse. Otherwise, allocate again.
In Versions later than Oracle 8.1.5, Oracle uses local tablespace management. For local tablespace management, a flag stored in each data file is used to manage the partition. For example, if the flag is 1, the partition is used. If the flag is 0, the partition is released.
