From: Tom Lane <tgl@sss.pgh.pa.us>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Lars Bergeson <larsavatar@gmail.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Query is slower with a large proportion of NULLs in several columns
Date: Tue, 21 Dec 2021 00:01:28 -0500
Message-ID: <2704544.1640062888@sss.pgh.pa.us> (raw)
In-Reply-To: <20211221045138.GZ17618@telsasoft.com>
References: <CAK66RGYim22Sd8-NvmufcxEQ_P99=UTAyJ9agnwDyEbCiVGEQg@mail.gmail.com>
<2688019.1640051519@sss.pgh.pa.us>
<CAK66RGbd8n46xEp3fTKOa3pO3eC=NT8tEHHZYjuNZq4Y0SQHTw@mail.gmail.com>
<20211221045138.GZ17618@telsasoft.com>
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
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, pryzby@telsasoft.com, larsavatar@gmail.com, pgsql-performance@lists.postgresql.org
Subject: Re: Query is slower with a large proportion of NULLs in several columns
In-Reply-To: <2704544.1640062888@sss.pgh.pa.us>
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