12.3号－－－Oracle 11g中数据库能有多大？

根据11g release 2文档《Oracle® Database Reference 11g Release 2 (11.2)》，我们可以计算出11g中数据库大小的一个理论极限:

Physical Database Limits

Item	Type of Limit	Limit Value
Database Block Size	Minimum	2048 bytes; must be a multiple of operating system physical block size
Database Block Size	Maximum	Operating system dependent; never more than 32 KB
Database Blocks	Minimum in initial extent of a segment	2 blocks
Database Blocks	Maximum per datafile	Platform dependent; typically 222 – 1 blocks
Controlfiles	Number of control files	1 minimum; 2 or more (on separate devices) strongly recommended
Controlfiles	Size of a control file	Dependent on operating system and database creation options; maximum of 20,000 x (database block size)
Database files	Maximum per tablespace	Operating system dependent; usually 1022
Database files	Maximum per database	65533 May be less on some operating systems Limited also by size of database blocks and by the DB_FILES initialization parameter for a particular instance
Database extents	Maximum per dictionary managed tablespace	4 GB * physical block size (with K/M modifier); 4 GB (without K/M modifier)
Database extents	Maximum per locally managed (uniform) tablespace	2 GB * physical block size (with K/M modifier); 2 GB (without K/M modifier)
Database file size	Maximum	Operating system dependent. Limited by maximum operating system file size; typically 222 or 4 MB blocks
MAXEXTENTS	Default value	Derived from tablespace default storage or DB_BLOCK_SIZE initialization parameter
MAXEXTENTS	Maximum	Unlimited
Redo Log Files	Maximum number of logfiles	Limited by value of MAXLOGFILES parameter in the CREATE DATABASE statementControl file can be resized to allow more entries; ultimately an operating system limit
Redo Log Files	Maximum number of logfiles per group	Unlimited
Redo Log File Size	Minimum size	4 MB
Redo Log File Size	Maximum Size	Operating system limit; typically 2 GB
Tablespaces	Maximum number per database	64 K Number of tablespaces cannot exceed the number of database files because each tablespace must include at least one file
Bigfile Tablespaces	Number of blocks	A bigfile tablespace contains only one datafile or tempfile, which can contain up to approximately 4 billion ( 232 ) blocks. The maximum size of the single datafile or tempfile is 128 terabytes (TB) for a tablespace with 32 K blocks and 32 TB for a tablespace with 8 K blocks.
Smallfile (traditional) Tablespaces	Number of blocks	A smallfile tablespace is a traditional Oracle tablespace, which can contain 1022 datafiles or tempfiles, each of which can contain up to approximately 4 million (222) blocks.
External Tables file	Maximum size	Dependent on the operating system.An external table can be composed of multiple files.

11g中当采用32 K块时单个表空间最大可以扩展到128 TB，而一个数据库最多拥有64 K个表空间，则可以得出单个数据库的理论最大值为128TB *64 K= 8192 PB= 8EB，该数据与Oracle 10g 数据库的容量持平，换而言之11g中数据库的容量并未增加。

Youtube视频网站一年产生的信息量大约在800TB，世界上1000强的公司所有数据库的总数据量约合1EB(平均一个公司1PB)，而64位可寻址内存的最大容量为16EB，理论上我们可以把所有这些少于8EB的信息存储到您的笔记本上安装的Oracle数据库中，而且可以将它们完全缓存到内存中以供读取。

在几年前没有人相信TB级别的数据库会在不久后普及，但是我们今天可以很自信地说随着TB级别的数据库不断涌现，无论从硬件角度或者软件角度支撑该数量级的数据库的solution都已经十分成熟了。

在11g未来的日子里，我们将注目于EB级数据库的出现！