Accessing data on Microsoft SQL Server from a PostgreSQL function

Question

I have an application that uses PostgreSQL but also interacts with a third-party-controlled database on MSSQL. The data are sometimes tied together closely enough that it becomes desirable to do things like:

select thing_from_pg, thing_from_ms_crossover_function(thing_from_pg) -- etc

Currently I implement thing_from_ms_crossover_function in plperl. Is there a way to do this in plpgsql or something, so that I don't need to start a plperl interpreter for such cases?

Another option is obviously to access both databases from my client app, but that becomes far less convenient than the view syntax above.

Answer 1

You have two basic options, well three basic ones rather.

The first is to use DBI-Link and then access this via your pl/pgsql or pl/perl function. The nice thing about DBI-Link is that it is relatively older and mature. If it works for you I would start there.

The second option is to use foreign data wrappers.

The third option is to write a more general framework in something like pl/perl that you can call from pl/pgsql. However at that point you are basically looking at re-inventing DBI-Link so I think you are better off starting with DBI-Link and modifying it as needed.