The working principle of oracle_fdw？ about oracle_fdw HOT 7 CLOSED

As long as you don't access foreign tables, oracle_fdw should have no impact on the performance of PostgreSQL.
If you read from a foreign table, and the query on the Oracle side takes a long time, or if the data transfer rate is slow, that will also affect the performance on the PostgreSQL side.

from oracle_fdw.

@ruralqiu , this is very common description. Full list of PostgreSQL functions implemented by oracle_fdw and executed for OracleDB or inside of OracleDB is here.

from oracle_fdw.

Yes, your description is pretty accurate. Another way to think of it is that a foreign table is somewhat like a view: it does not store any data, and whenever you read or write, it is actually the underlying Oracle table that is accessed.

from oracle_fdw.

Yes, your description is pretty accurate. Another way to think of it is that a foreign table is somewhat like a view: it does not store any data, and whenever you read or write, it is actually the underlying Oracle table that is accessed.

OK，So I can understand it as follows: there is no relationship between oracle_fdw and the performance of the postgreSQL environment, is it？

from oracle_fdw.

As long as you don't access foreign tables, oracle_fdw should have no impact on the performance of PostgreSQL. If you read from a foreign table, and the query on the Oracle side takes a long time, or if the data transfer rate is slow, that will also affect the performance on the PostgreSQL side.

Okay,thanks, I understand now. Will I use indexes to improve query speed when I create indexes in Oracle tables that are mapped externally?

from oracle_fdw.

Indexes on the Oracle side will get used at the discretion of Oracle. PostgreSQL knows nothing about them. All it does is send a query (look at the EXPLAIN output), and Oracle decides if it wants to use an index or not (look at the EXPLAIN (VERBOSE) output).

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Okay, thank you very much

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