Re: postgres_fdw join pushdown (was Re: Custom/Foreign-Join-APIs)

<div dir="ltr">During join planning, the planner tries multiple combinations of joining relations, thus the same base
orjoin relation can be part of multiple of combination. Hence remote_conds or joinclauses will get linked multiple
timesas they are bidirectional lists, thus breaking linkages of previous join combinations tried. E.g. while planning A
joinB join C join D planner will come up with combinations like A(B(CD)) or (AB)(CD) or ((AB)C)D etc. and remote_conds
fromA will first be linked into A(B(CD)), then AB breaking the first linkages.<br /></div><div class="gmail_extra"><br
/><divclass="gmail_quote">On Tue, Feb 16, 2016 at 11:36 AM, Etsuro Fujita <span dir="ltr"><<a
href="mailto:fujita.etsuro@lab.ntt.co.jp"target="_blank">fujita.etsuro@lab.ntt.co.jp</a>></span> wrote:<br
/><blockquoteclass="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span
class="">On2016/02/15 21:33, Ashutosh Bapat wrote:<br /><blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px#ccc solid;padding-left:1ex"> Here's patch with better way to fix it. I think while concatenating
the<br/> lists, we need to copy the lists being appended and in all the cases. If<br /> we don't copy, a change in
thoselists can cause changes in the upward<br /> linkages and thus lists of any higher level joins.<br
/></blockquote><br/></span> Maybe I'm missing something, but I don't understand why such a change in those lists
happens. Could you explain about that in more detail?<br /><br /> Best regards,<br /> Etsuro Fujita<br /><br /><br
/></blockquote></div><br/><br clear="all" /><br />-- <br /><div class="gmail_signature"><div dir="ltr">Best Wishes,<br
/>AshutoshBapat<br />EnterpriseDB Corporation<br />The Postgres Database Company<br /></div></div></div>