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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Justin Pryzby <pryzby@telsasoft.com>
cc: Lars Bergeson <larsavatar@gmail.com>,
        pgsql-performance@lists.postgresql.org
Subject: Re: Query is slower with a large proportion of NULLs in several
 columns
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Comments: In-reply-to Justin Pryzby <pryzby@telsasoft.com>
	message dated "Mon, 20 Dec 2021 22:51:38 -0600"
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Justin Pryzby <pryzby@telsasoft.com> writes:
> On Mon, Dec 20, 2021 at 08:11:42PM -0800, Lars Bergeson wrote:
>> Still taking 10X more I/O to read the smaller table. Very odd.

> If I'm not wrong, it's even worse than that ?
> It takes 20 or 30sec to run the query - but it says the associated I/O times
> are ~500sec or ~6000sec ?

It would help if somebody had labeled the units of I/O Time
... but I'm guessing those are microsec vs. the millisec
of the other times, because otherwise it's completely wrong.

			regards, tom lane