Oracle修改dblink连接数

alter system set open_links=10 scope=spfile;alter system set open_links_per_instance=10 scope=spfile;

OPEN_LINKS

PropertyDescriptionParameter typeIntegerDefault value4ModifiableNoRange of values0 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.

OPEN_LINKS_PER_INSTANCE

PropertyDescriptionParameter typeIntegerDefault value4ModifiableNoRange of values0 to 4294967295 (4 GB -1)Oracle RACMultiple 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.