Re: Improving our clauseless-join heuristics - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Improving our clauseless-join heuristics
Date
Msg-id 29472.1334547594@sss.pgh.pa.us
Whole thread Raw
In response to Re: Improving our clauseless-join heuristics  (Amit Kapila <amit.kapila@huawei.com>)
Responses Re: Improving our clauseless-join heuristics  (Amit Kapila <amit.kapila@huawei.com>)
List pgsql-hackers
Amit Kapila <amit.kapila@huawei.com> writes:
> I want to clarify small doubt in this regard. 
> In function make_rels_by_clause_joins(..), it tries to join the given
> relation old_rel with other relations if there exist a join between them. 
> What I can understand is, it is because if there exists a join condition its
> better to join with that relation.
> However if the given relation old_rel is not able to join any relation, then
> why can't it try to make cross-join with other relations there itself.

Hm?  That case is handled by make_rels_by_clauseless_joins.  I suppose
we could refactor to combine those two functions, but what's the point?
If that's not what your question is about, then I don't understand.
        regards, tom lane


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