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` statement Control 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.