Date: Tue, 21 Dec 2021 15:13:37 -0600
From: Justin Pryzby <pryzby@telsasoft.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "David G. Johnston" <david.g.johnston@gmail.com>,
	Lars Bergeson <larsavatar@gmail.com>,
	pgsql-performance@lists.postgresql.org
Subject: Re: Query is slower with a large proportion of NULLs in several
 columns
Message-ID: <20211221211337.GB17618@telsasoft.com>
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On Tue, Dec 21, 2021 at 12:33:06AM -0500, Tom Lane wrote:
> So now we have a real mystery about what is happening on Lars'
> system.  Those numbers can't be right.

I realized Lars said it was x86_64/Linux, but I'm hoping to hear back with more
details:

What OS version?
Is it a VM of some type ?
How did you install postgres?  From a package or compiled from source?
grep -r HAVE_CLOCK_GETTIME /usr/pgsql-13/include
Send the exact command and output you used to run the query?
Why does your explain output have IO timing but not Buffers: hit/read ?

-- 
Justin