Re: Suggestion for Easier Cross-Database Query Handling in PostgreSQL

Frank,

Why doesn't the shared OID space make cross-database queries possible? SQL
Server does it, so the idea isn't that far-fetched.

On Fri, May 15, 2026 at 6:18 PM Frank Heikens <frank(at)elevarq(dot)com> wrote:

>
> Hi Shivam,
>
> Thank you for your feedback.
>
> One important difference is terminology.
>
> In MySQL, CREATE DATABASE and CREATE SCHEMA are essentially the same
> command, so what MySQL calls a “database” is effectively a schema
> (namespace).
>
> PostgreSQL also supports querying across schemas natively, so the same
> functionality is already available when the objects are in the same
> PostgreSQL database.
>
> In PostgreSQL, a database is a true isolation boundary with its own
> catalogs and connection context. Because of this design, direct joins
> across databases are not supported. When this is required, postgres_fdw is
> the recommended solution.
>
> So for most MySQL users, the equivalent approach in PostgreSQL is to use
> multiple schemas within a single database rather than multiple databases.
>
> Best regards,
> Frank Heikens
>
>
>
> > On May 15, 2026, at 3:06 PM, Shivam Pandey <shivampandey91199(at)gmail(dot)com>
> wrote:
> >
> > 
> > Hello PostgreSQL Team,
> >
> > I would like to share feedback from a developer perspective regarding
> cross-database querying in PostgreSQL.
> >
> > One feature that many developers appreciate in MySQL is the ability to
> directly query and join tables across multiple databases within the same
> server instance. This approach becomes very useful in real-world situations
> where applications need to access shared or distributed data quickly and
> efficiently.
> >
> > In PostgreSQL, achieving similar functionality often requires additional
> setup using extensions such as postgres_fdw or dblink. While these
> solutions are powerful and architecturally clean, they can feel complex for
> developers who are building applications rapidly or migrating from systems
> like MySQL.
> >
> > It would be valuable if PostgreSQL could provide a more
> developer-friendly and simplified native approach for cross-database
> querying while still maintaining PostgreSQL’s strong isolation and security
> principles.
> >
> > Possible improvements could include:
> >
> > 1)Simpler syntax for cross-database joins
> > 2) Easier configuration for trusted local databases
> > 3) Built-in lightweight federation support
> > 4) Better onboarding documentation for multi-database use cases
> >
> > PostgreSQL is already one of the most powerful and respected databases
> in the industry. Enhancing developer convenience in this area could make
> adoption even smoother for many teams.
> >
> > Thank you for your incredible work and continuous innovation.
> >
> > Best Regards,
> > Shivam Pandey
>

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