Oracle Transparent Gateway

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Oracle Transparent Gateway

We tried to use Oracle transparent gateway, we succesfully tried run query from oracle to Teradata. The purpose is to run joint query from teradata and oracle tables/views.
For the performance issue, We haven't tested to run the join query with large tables.

My questions are:
1. Is it suggested to run join query using Oracle transparent gateway considering the performance?
2. Is it also possible to run query from Teradata to Oracle (the same with from oracle to Teradata)?

Regards
Jonhoni N