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Oracle 数据库的限制(9iR2)

2013年01月04日 ⁄ 综合 ⁄ 共 2531字 ⁄ 字号 评论关闭

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

Maximum

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

Controlfiles

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

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

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

Database file size

Maximum

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

MAXEXTENTS

Default value

Derived from tablespace default storage or DB_BLOCK_SIZE initialization parameter

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

Maximum number of logfiles per group

Unlimited

Redo Log File Size

Minimum size

50 KB

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, as each tablespace must include at least one file

 

Process and Runtime Limits

Item Type Limit

Instances per database

Maximum number of cluster database instances per database

Operating system-dependent

Locks

Row-level

Unlimited

Distributed Lock Manager

Operating system dependent

SGA size

Maximum value

Operating system-dependent; typically 2 to 4 GB for 32-bit operating systems, and > 4 GB for 64-bit operating systems

Advanced Queuing Processes

Maximum per instance

10

Job Queue Processes

Maximum per instance

1000

I/O Slave Processes

Maximum per background process (DBWR, LGWR, etc.)

15

Maximum per Backup session

15

Sessions

Maximum per instance

32 KB; limited by the PROCESSES and SESSIONS initialization parameters

Global Cache Service Processes

Maximum per instance

10

Shared Servers

Maximum per instance

Unlimited within constraints set by the PROCESSES and SESSIONS initialization parameters, for instance

Dispatchers

Maximum per instance

Unlimited within constraints set by PROCESSES and SESSIONS initialization parameters, for instance

Parallel Execution Slaves

Maximum per instance

Unlimited within constraints set by PROCESSES and SESSIONS initialization parameters, for instance

Backup Sessions

Maximum per instance

Unlimited within constraints set by PROCESSES and SESSIONS initialization parameters, for instance

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