Re: should we have a fast-path planning for OLTP starjoins?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Nico Williams <nico(at)cryptonector(dot)com>
Cc: Tomas Vondra <tomas(at)vondra(dot)me>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: should we have a fast-path planning for OLTP starjoins?
Date: 2025-11-15 15:57:07
Message-ID: 3353330.1763222227@sss.pgh.pa.us
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Nico Williams <nico(at)cryptonector(dot)com> writes:
> Some unsolicited advice:
> ...
> But here you can just use the order that the SQL uses. It gives the
> author some power.

If that's the approach you want, it's been possible for decades:
"set join_collapse_limit = 1" and away you go. I don't feel a
need to invent a different version of that for star schemas.

I do not think this patch should have ambitions beyond the stated
one of avoiding useless join-order search effort. If you try to
load more than that onto the plate you'll probably end in failure.

regards, tom lane

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