|From:||Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>|
|To:||Guyren Howe <guyren(at)gmail(dot)com>, PostgreSQL General <pgsql-general(at)postgresql(dot)org>|
|Subject:||Re: First-class Polymorphic joins?|
|Views:||Raw Message | Whole Thread | Download mbox|
On 08/13/2015 05:23 PM, Guyren Howe wrote:
> It surprises me that no SQL database to my knowledge has polymorphic joins as a first-class feature.
> A polymorphic join is where a fk contains not just an id but an indicator of which table it refers to.
I am pretty sure it already does that:
REFERENCES reftable [ ( refcolumn ) ]
So you could have a "tags" table, that can attach tags to any of a
variety of other tables. Rails handles this by including the table name
as a string.
> This seems a reasonable thing to want to do, and it seems that the database could handle it by combining the fields from the target tables in the result.
> I also think migrations ought to be a first-class feature…
So is this the push the ORM into the database day?
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