Horton

Re: NOT IN subquery optimization

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Steele <david@pgmasters.net>
Cc: David Rowley <david.rowley@2ndquadrant.com>, "Li, Zheng" <zhelli@amazon.com>, "Finnerty, Jim" <jfinnert@amazon.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2019-03-05T14:37:55Z
Lists: pgsql-hackers 
David Steele <david@pgmasters.net> writes:
> I'm not sure if I have an issue with competing patches on the same 
> thread.  I've seen that before and it can lead to a good outcome.  It 
> case, as you say, also lead to confusion.

It's a bit of a shame that the cfbot will only be testing one of them
at a time if we leave it like this.  I kind of lean towards the
two-thread, two-CF-entry approach because of that.  The amount of
confusion is a constant.

			regards, tom lane

Commits

  1. Check we don't misoptimize a NOT IN where the subquery returns no rows.