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 of25,000 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.