Oracle 数据库的限制(9iR2)
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
22
2 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 phttp://blog.csdn.net/fenng/archive/2004/07/20/rocess (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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