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Oracle9i Database Reference
Release 2 (9.2)

Part Number A96536-02
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Physical Database Limits

Item Type of Limit Limit Value

Database Block Size


2048 bytes; must be a multiple of operating system physical block size


Operating system dependent; never more than 32 KB

Database Blocks

Minimum in initial extent of a segment.

2 blocks

Maximum per datafile

Platform dependent; typically 222-1 blocks


Number of control files

1 minimum; 2 or more (on separate devices) strongly recommended

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

Maximum per database


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


4 GB, regardless of the maximum file size allowed by the operating system

Database file size


Operating system dependent. Limited by maximum operating system file size; typically 222 or 4M blocks


Default value

Derived from tablespace default storage or DB_BLOCK_SIZE initialization parameter



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

Maximum number of logfiles per group


Redo Log File Size

Minimum size

50 KB

Maximum size

Operating system limit; typically 2 GB


Maximum number per database

64 K

Number of tablespaces cannot exceed the number of database files, as each tablespace must include at least one file