How does Oracle11g modify open_links parameters -- concurrency

1. open_links meaning OPEN_LINKS_PER_INSTANCEspecifiesthemaximumnumberofmigratableopenconnectionsgloballyforeachd

1. open_links meaning OPEN_LINKS_PER_INSTANCE specifies the maximum number of migratable open connections globally for each d

1. open_links meaning

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.
Possible errors:

ORA-02020: too relational 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. View open_links

Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0
Connected as SYS
SQL> show parameters open_links;
NAME TYPE VALUE
-----------------------------------------------------------------------------
Open_links integer 4
Open_links_per_instance integer 4

3. Modify open_links

Alter system set open_links = 255 scope = spfile;
Alter system set open_links_per_instance = 255 scope = spfile;

4. Make the modified open_links take effect

After modification, check that the value has not changed.

SQL> show parameters open_links;
NAME TYPE VALUE
-----------------------------------------------------------------------------
Open_links integer 4
Open_links_per_instance integer 4
SQL> alter system set open_links = 255 scope = spfile;
System altered
SQL> alter system set open_links_per_instance = 255 scope = spfile;
System altered
SQL>
SQL> show parameters open_links;
NAME TYPE VALUE
-----------------------------------------------------------------------------
Open_links integer 4
Open_links_per_instance integer 4
SQL>

Restart the database to view the changes:

[Oracle @ eds2db ~] $ Dbshut
ORACLE_HOME_LISTNER is not SET, unable to auto-stop Oracle Net Listener
Usage:/u01/app/oracle/db/bin/dbshut ORACLE_HOME
Processing Database instance "wg97": log file/u01/app/oracle/db/shutdown. log
[Oracle @ eds2db ~] $ Dbstart
ORACLE_HOME_LISTNER is not SET, unable to auto-start Oracle Net Listener
Usage:/u01/app/oracle/db/bin/dbstart ORACLE_HOME
Processing Database instance "wg97": log file/u01/app/oracle/db/startup. log
[Oracle @ eds2db ~] $

SQL> show parameters open_links;
NAME TYPE VALUE
-----------------------------------------------------------------------------
Open_links integer 255
Open_links_per_instance integer 255

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