One database queries another:

I have a project condition under which I need to get at data on a frequently updated Oracle 9i server--but at the same time its schema

should not in any way be contacted, other than to query it. But queried in a way that allows the secondhand db to be set up as something

approximating a real time mirror.

The live server specifically cannot be modified, cannot be added onto.

So I would like to attempt an environment in which my secondhand database periodically makes a query against the Oracle server, and stores

that data.

So how does a database system, say MySQL, poll against a separate Oracle db? What is the minimum footprint of middleware that enables that

coordination and direct data transfer?

Better yet, can one Oracle 9i database (or schema) be set up to automatically query a separate Oracle database on a regular schedule--

perhaps every second?

Thanks for any response.

Let the source database propagate changes after registering data itself

How does this work? Is this a feature of Oracle 9i? Is there a configuration setting inside of it that has a check box which says, more or less, "[X] Propagate changes after registering data myself"?

Or is that just a generalized strategy?

Also does this involve fiddling with that database (in order to set up such a propagation)?

Thanks.

No
Yes
Yes, no free lunch generally speaking