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From: Merlin Moncure <mmoncure@gmail.com>
Date: Tue, 7 Jul 2026 14:34:29 -0600
Message-ID: 
 <CAHyXU0zSj1SXxyWr-Jwk7SVEMGDsKu9VtT6vJLPyWqaHtVFaYA@mail.gmail.com>
Subject: Re: Suggestion for Easier Cross-Database Query Handling in PostgreSQL
To: Isaac Morland <isaac.morland@gmail.com>
Cc: Shivam Pandey <shivampandey91199@gmail.com>, pgsql-general@postgresql.org
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On Fri, May 15, 2026 at 8:15=E2=80=AFPM Isaac Morland <isaac.morland@gmail.=
com>
wrote:

> On Fri, 15 May 2026 at 18:06, Shivam Pandey <shivampandey91199@gmail.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 situati=
ons
>> where applications need to access shared or distributed data quickly and
>> efficiently.
>>
>
> What MySQL calls databases PostgreSQL calls schemas, and PostgreSQL
> certainly has the ability to query and join tables across schemas.
>
> What MySQL might call an instance (a collection of MySQL databases)
> PostgreSQL calls a database (a collection of PostgreSQL schemas). A singl=
e
> PostgreSQL instance has the ability to host multiple databases (albeit
> sharing a single set of roles and role relationships). Can MySQL query an=
d
> join across multiple instances?
>

mysql treats SCHEMA and DATABASE the same.   So the features are at parity
from an isolation standpoint.  (This is also why you won't get this feature
since most of the benefits from cross database querying are already
present).

Besides. postgres schemas are better in pretty much every way, mainly due
to the games you can play with search_path and plan invalidation,
especially in p/pgsql.

merlin

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<div dir=3D"ltr"><div dir=3D"ltr"><span style=3D"background-color:transpare=
nt">On Fri, May 15, 2026 at 8:15=E2=80=AFPM Isaac Morland &lt;<a href=3D"ma=
ilto:isaac.morland@gmail.com">isaac.morland@gmail.com</a>&gt; wrote:</span>=
</div><div class=3D"gmail_quote gmail_quote_container"><blockquote class=3D=
"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(2=
04,204,204);padding-left:1ex"><div dir=3D"ltr"><div dir=3D"ltr">On Fri, 15 =
May 2026 at 18:06, Shivam Pandey &lt;<a href=3D"mailto:shivampandey91199@gm=
ail.com" target=3D"_blank">shivampandey91199@gmail.com</a>&gt; wrote:<br></=
div><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"m=
argin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left=
:1ex"><div dir=3D"auto">Hello PostgreSQL Team,<div dir=3D"auto"><br></div><=
div dir=3D"auto">I would like to share feedback from a developer perspectiv=
e regarding cross-database querying in PostgreSQL.</div><div dir=3D"auto"><=
br></div><div dir=3D"auto">One feature that many developers appreciate in M=
ySQL is the ability to directly query and join tables across multiple datab=
ases within the same server instance. This approach becomes very useful in =
real-world situations where applications need to access shared or distribut=
ed data quickly and efficiently.</div></div></blockquote><div><br></div><di=
v>What MySQL calls databases PostgreSQL calls schemas, and PostgreSQL certa=
inly has the ability to query and join tables across schemas.</div><div><br=
></div><div>What MySQL=C2=A0might call an instance (a collection of MySQL d=
atabases) PostgreSQL calls a database (a collection of PostgreSQL schemas).=
 A single PostgreSQL instance has the ability to host multiple databases (a=
lbeit sharing a single set of roles and role relationships). Can MySQL quer=
y and join across multiple instances?</div></div></div></blockquote><div><b=
r></div><div>mysql treats SCHEMA and DATABASE the same.=C2=A0 =C2=A0So the =
features are at parity from an isolation standpoint.=C2=A0 (This is also wh=
y you won&#39;t get this feature since most of the benefits from cross data=
base querying are already present).</div><div><br></div><div>Besides. postg=
res schemas are better in pretty much every way, mainly due to the games yo=
u can play with search_path and plan invalidation, especially in p/pgsql.</=
div><div><br></div><div>merlin</div></div></div>

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