| From: | Julien Rouhaud <rjuju123(at)gmail(dot)com> |
|---|---|
| To: | Joel Jacobson <joel(at)compiler(dot)org> |
| Cc: | Isaac Morland <isaac(dot)morland(at)gmail(dot)com>, Vik Fearing <vik(at)postgresfriends(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Idea: Avoid JOINs by using path expressions to follow FKs |
| Date: | 2021-03-31 17:16:44 |
| Message-ID: | CAOBaU_a6fx+W7PSgEqyn7WNvdh6_6MTnPpXCyK7ts1XVWia+WA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Mar 31, 2021 at 5:19 PM Joel Jacobson <joel(at)compiler(dot)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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