Re: NOT IN subquery optimization

On Fri, 1 Mar 2019 at 15:27, Richard Guo <riguo@pivotal.io> wrote:
> I have reviewed your patch. Good job except two issues I can find:
>
> 1. The patch would give wrong results when the inner side is empty. In this
> case, the whole data from outer side should be in the outputs. But with the
> patch, we will lose the NULLs from outer side.
>
> 2. Because of the new added predicate 'OR (var is NULL)', we cannot use hash
> join or merge join to do the ANTI JOIN.  Nested loop becomes the only choice,
> which is low-efficency.

Yeah. Both of these seem pretty fundamental, so setting the patch to
waiting on author.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
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