Re: NOT IN subquery optimization - Mailing list pgsql-hackers

From David Rowley
Subject Re: NOT IN subquery optimization
Date
Msg-id CAKJS1f9o+f-xH8TGHJnuAM_RjjTxV6hTVOxiMKjrfdcjWiSzzA@mail.gmail.com
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In response to Re: NOT IN subquery optimization  ("Li, Zheng" <zhelli@amazon.com>)
List pgsql-hackers
On Wed, 27 Feb 2019 at 13:05, Li, Zheng <zhelli@amazon.com> wrote:
> -With the latest fix (for the empty table case), our patch does the transformation as long as the outer is
non-nullableregardless of the inner nullability, experiments show that the results are always faster.
 

Hi Zheng,

I'm interested to know how this works without testing for inner
nullability.  If any of the inner side's join exprs are NULL then no
records can match. What do you propose to work around that?

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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