Re: Passing more context info to selectivity-estimation code

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Passing more context info to selectivity-estimation code
Date: 2007-05-20 17:07:39
Message-ID: 2226.1179680859@sss.pgh.pa.us
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Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
> Tom Lane wrote:
>> Comments, better ideas?

> How about building a separate Var-node for the variable when it's above
> an outer join?

[ itch... ] That would be a whole lot *more* invasive than what I'm
proposing now. It might be an interesting avenue to pursue,
particularly in conjunction with the planner's inability to deal with
non-nullable expressions in subselect outputs below outer joins (which
seems to require some special kind of Var to fix). But I can't see
back-patching it.

regards, tom lane

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