Re: Idea: Avoid JOINs by using path expressions to follow FKs - Mailing list pgsql-hackers

From Julien Rouhaud
Subject Re: Idea: Avoid JOINs by using path expressions to follow FKs
Date
Msg-id CAOBaU_a6fx+W7PSgEqyn7WNvdh6_6MTnPpXCyK7ts1XVWia+WA@mail.gmail.com
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In response to Re: Idea: Avoid JOINs by using path expressions to follow FKs  ("Joel Jacobson" <joel@compiler.org>)
Responses Re: Idea: Avoid JOINs by using path expressions to follow FKs  ("Joel Jacobson" <joel@compiler.org>)
List pgsql-hackers
On Wed, Mar 31, 2021 at 5:19 PM Joel Jacobson <joel@compiler.org> wrote:
>
> If using the -> notation, you would only need to manually
> inspect the tables involved in the remaining JOINs;
> since you could be confident all uses of -> cannot affect cardinality.

Talking about that, do you have some answers to the points raised in
my previous mail, which is how it's supposed to behave when a table is
both join using your "->" syntax and a plain JOIN, how to join the
same table multiple time using this new syntax, and how to add
predicates to the join clause using  this new syntax.

> I think this would be a win also for an expert SQL consultant working
> with a new complex data model never seen before.

By experience if the queries are written with ANSI JOIN it's not
really a problem.  And if it's a new complex data model that was never
seen, I would need to inspect the data model first anyway to
understand what the query is (or should be) doing.



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