DBLINKS and Network Traffic

I am interested in understanding the difference in network traffic between a direct client session with a remote database, call it REMOTE1, and a session where I am connecting with REMOTE1 via a database link created at my Oracle server, call it HOST1.

I noticed that when connecting directly with REMOTE1 using SQLPLUS, Oracle checked my client TNSNAMES.ORA for service names. I was successful because my client TNSNAMES.ORA included the service name for REMOTE1. But when I connected with HOST1 using SQLPLUS, and tried to query a table in REMOTE1 using my database link, ORACLE initially could not recognize the service name. This was because it was reading the TNSNAMES.ORA on the HOST1 server, which did not include REMOTE1's service name.

After adding the service name to the HOST1 TNSNAMES.ORA, I still could not query a REMOTE1 table, getting a TNS-012203 SQLNET error.

The fact that the database link way of accessing REMOTE1 was using a different TNSNAMES.ORA indicates a fundamentally different network path for database links. Also the TNS-012203 error seems to suggest a network problem that did not occur with my direct connection to REMOTE1.

The HOST1(Netware 4.11) and REMOTE1(NT 4.0) servers are in the same building and can see each other over a T-100 copper connection.

I hope that my story was clear, and that someone can shed some light on the issue.

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Share what you know. Learn what you don't. Received on Fri Aug 27 1999 - 12:17:28 CDT