Re: How does postgres store the join predicate for a relation in a given query

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Gourav Kumar <gourav1905(at)gmail(dot)com>
Cc: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: How does postgres store the join predicate for a relation in a given query
Date: 2017-10-12 16:38:36
Message-ID: 30260.1507826316@sss.pgh.pa.us
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Gourav Kumar <gourav1905(at)gmail(dot)com> writes:
> I have the RelOptInfo data structure for the relations which are to be
> joined but when I check their joininfo, it is empty.

You aren't telling us anything much about the case you're studying,
but if the join clauses have the form of equality comparisons, they
likely got converted into EquivalenceClass data structures instead.
These days the joininfo lists only contain "unstructured" join
conditions.

regards, tom lane

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