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Re: Improving our clauseless-join heuristics

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: 2012-04-18 05:06:29
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Lists: pgsql-hackers
Amit Kapila <amit(dot)kapila(at)huawei(dot)com> writes:
>> I might still be misunderstanding, but I think what you are suggesting
>> is that in the loop in make_rels_by_clause_joins, if we find that the
>> old_rel doesn't have a join clause/restriction with the current
>> other_rel, we check to see whether other_rel has any join clauses at
>> all, and force the join to occur anyway if it doesn't.

> It is on similar lines, but the only difference is that it will try to join 
> old_rel with other_rel list incase 
> old_rel is not able to join with any of other_rel in the list with proper
> join clause between them. 

I'm afraid I'm still not following you very well.  Perhaps you could
submit a proposed patch?

			regards, tom lane

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