open_links_per_instance 和 open_links 参数说明
来源:互联网 发布:51单片机最小系统 编辑:程序博客网 时间:2024/05/02 16:33
一. 先看官网的说明
1.1 OPEN_LINKS
Property
Description
Parameter type
Integer
Default value
4
Modifiable
No --即修改需要重启实例
Range of values
0 to 255
OPEN_LINKS specifies the maximum number of concurrent open connections to remote databases in one session. These connections include database links, as well as external procedures and cartridges, each of which uses a separate process.
Oracle counts one open link for the following:
For each user that references a public or private database link
For each external procedure or cartridge connection when it is executed for the first time
Both types of connections close when the session ends. You can also close a database link connection explicitly by issuing an ALTER SESSION CLOSE DATABASE LINK statement.
You should set this parameter to allow for the external procedure and cartridge connections expected during the session plus the number of databases referred to in typical distributed transactions (that is, a single SQL statement that references multiple databases), so that all the databases can be open to execute the statement.
For example, if queries alternately access databases A, B, and C, and OPEN_LINKS is set to 2, time will be lost waiting while one connection is broken and another made. Increase the value if many different databases are accessed over time.
This parameter refers only to connections used for distributed transactions. Direct connections to a remote database specified as an application connects are not counted.
If you set OPEN_LINKS to 0, then no distributed transactions are allowed.
1.2 OPEN_LINKS_PER_INSTANCE
Property
Description
Parameter type
Integer
Default value
4
Modifiable
No
Range of values
0 to 4294967295 (4 GB -1)
Oracle RAC
Multiple instances can have different values.
OPEN_LINKS_PER_INSTANCE specifies the maximum number of migratable open connections globally for each database instance. XA transactions use migratable open connections so that the connections are cached after a transaction is committed. Another transaction can use the connection, provided the user who created the connection is the same as the user who owns the transaction.
OPEN_LINKS_PER_INSTANCE is different from OPEN_LINKS, which indicates the number of connections from a session. The OPEN_LINKS parameter is not applicable to XA applications.
二. 查看并修改
2.1 查看
SQL> show parameter open
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
open_cursors integer 300
open_links integer 4
open_links_per_instance integer 4
read_only_open_delayed boolean FALSE
session_max_open_files integer 10
2.2 与这个参数有关的错误是ORA-02020
ORA-02020: too many database links in use
Cause: The current session has exceeded the INIT.ORA open_links maximum.
Action: Increase the open_links limit, or free up some open links by committing or rolling back the transaction and canceling open cursors that reference remote databases.
2.3 修改该参数
之前说过, 修改这个参数需要重启实例。可以只修改spfile里的值。 如:
SQL> alter system set open_links=10;
alter system set open_links=10
*
第 1 行出现错误:
ORA-02095: 无法修改指定的初始化参数
SQL> alter system set open_links=10 scope=spfile;
系统已更改。
在次查看:
SQL> show parameter open_links
NAME TYPE VALUE
------------------------------------ ----------- -------
open_links integer 4
open_links_per_instance integer 4
修改没有生效,还是需要重启实例的。
------------------------------------------------------------------------------
- open_links_per_instance 和 open_links 参数说明
- open_links_per_instance 和 open_links 参数说明
- open_links_per_instance 和 open_links 参数说明
- open_links_per_instance 和 open_links 参数说明
- open_links_per_instance 和 open_links 参数说明
- open_links_per_instance 和 open_links 参数说明
- SetSocketopt()和getsocketopt() 参数说明
- impdp 和expdp参数说明
- innodb_flush_log_at_trx_commit和sync_binlog 参数说明
- haproxy 配置和参数说明
- innodb_log_buffer_size和innodb_buffer_pool_size参数说明
- MaxTenuringThreshold 和 TargetSurvivorRatio参数说明
- innodb_flush_log_at_trx_commit和sync_binlog 参数说明
- setsockopt和getsockopt参数说明和使用
- 网页弹出窗口和iframe参数说明
- 网页弹出窗口和iframe参数说明
- eclipse常用快捷方式 和 启动参数 说明
- Hydrax简介和HydraxDemo.hdx参数说明
- exp/imp 与 expdp/impdp 对比 及使用中的一些优化事项
- 在linux下使用curl访问 多参数url GET参数问题
- java创建临时文件
- Ubuntu源设置
- oracle伪列 rowid和rownum
- open_links_per_instance 和 open_links 参数说明
- linux 客户端 Socket 非阻塞connect编程
- Linux设备驱动工程师之路——网络设备驱动基本原理和框架
- Java_9_28课堂总结
- xml文件解析办法
- 7个改变世界的Java项目
- 在一个论坛上看到的,可以学习与借鉴!
- 关于err C2065: 'sprintf_instead_use_StringCbPrintfA_or_StringCchPrintfA' : undeclared identifer.
- Oracle 修改DB_NAME 和 DBID