Pass through query aka openquery

Hi,

We are have setup a infromix odbc connection under HS to our remote informix server and select from data for processing.

We have also ms sql server setup with the same informix odbc connection as well.

When we use oracle to select data, the performance is very slow. The benchmark we get is like 5-6 seconds to return a result.

Where as when we use ms sql to select data with openquery it is very fast Typically we get around 1-1.5 seconds only.

openquery is built in ms sql and it is free of charge.

We are asking what is the openquery equivalent in oracle ?

or

How do we perform pass through query on odbc connection under HS? What is the command or syntax?

Thank you.