In this example, a view was created in order to limit the records that users could retrieve. If no
such restriction is necessary, a synonym can be used instead. This is shown in the following example:
create public synonym EMPLOYEE for EMPLOYEE@HR_LINK;
Local users who query the local public synonym EMPLOYEE will automatically have their queries
redirected to the EMPLOYEE table in the LOC instance on the HQ server. Location transparency
has thus been achieved.
By default, a single SQL statement can use up to four database links. This limit can be increased
via the OPEN_LINKS parameter in the database??™s SPFILE or init.ora file. If this value is set to 0, no
distributed transactions are allowed.
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540 Oracle Database 11g DBA Handbook
Tuning Oracle Net
Tuning Oracle Net applications is fairly straightforward: Wherever possible, reduce the amount
of data that is sent across the network, particularly for online transaction-processing applications.
Also, reduce the number of times data is requested from the database. The basic procedures that
should be applied include the following:
The use of distributed objects, such as materialized views, to replicate static data to
remote databases.
The use of procedures to reduce the amount of data sent across the network. Rather than
data being sent back and forth, only the procedure??™s error status is returned.
The use of homogenous servers wherever possible to eliminate the need for connection
managers.
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