From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Amit Kapila <amit(dot)kapila(at)huawei(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Improving our clauseless-join heuristics |
Date: | 2012-04-19 05:33:13 |
Message-ID: | 10101.1334813593@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Amit Kapila <amit(dot)kapila(at)huawei(dot)com> writes:
> The way I am telling was as below code.
> With this extra paths will get generated, but it will as well consider for
> joining c and d in query:
> select * from a, b, c, d where a.x = b.y and (a.z = c.c or a.z = d.d)
I think this would just be dead code as of HEAD. With the recent
changes in the definition of have_relevant_joinclause, if we get into
make_rels_by_clause_joins there should always be at least one other
relation that the old_rel is considered to join to. In any case,
I don't see the point of adding more logic to make_rels_by_clause_joins
unless it allows us to take out as much or more work elsewhere.
regards, tom lane
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