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.