Physical Database Limits

This table describes limit types and limit values for physical database items.

Item	Type of Limit	Limit Value
Controlfiles	Number of control files	`1` minimum; `2` or more (on separate devices) strongly recommended
Controlfiles	Size of a control file	Maximum of 201031680 logical blocks
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
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	`256` KB * physical block size
Database file size	Maximum	Operating system dependent. Limited by maximum operating system file size. See the Bigfile Tablespaces and Smallfile (traditional) Tablespaces rows for more information about the maximum database file size in these types of tablespaces.
Database files	Maximum per tablespace	Operating system dependent; usually `1023`
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
External Tables file	Maximum size	Dependent on the operating system An external table can be composed of multiple files.
`MAXEXTENTS`	Default value	Derived from tablespace default storage or `DB_BLOCK_SIZE` initialization parameter
`MAXEXTENTS`	Maximum	Not defined
Redo Log File Size	Minimum size	`4 MB`
Redo Log File Size	Maximum Size	Operating system limit; typically `2` TB
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	Not defined
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 1023 datafiles or tempfiles, each of which can contain up to approximately 4 million (2²²) blocks.