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Date: Mon, 21 Aug 2023 09:47:05 -0500
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Subject: Re: Why doesn't autovacuum/analyze run in due time after calling
 pg_stat_reset?
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From: Ron <ronljohnsonjr@gmail.com>
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On 8/20/23 14:10, Rihad wrote:
> On 8/20/23 20:22, Adrian Klaver wrote:
>> On 8/18/23 22:35, Rihad wrote:
>>> On 8/17/23 13:01, rihad wrote:
>>>>
>>>> Hi, all. After calling pg_stat_reset all statistics used by autovacuum 
>>>> got zeroed, and started accumulating from scratch. Some tables get 
>>>> acted upon properly, some don't.
>>>>
>>>>
>>> Self-replying: yup, it seems there's an arbitrary limit of 100K of 
>>> n_live_tup after which autovac/analyze kicks in, or it seems so.
>>
>> To know rather then guess read:
>>
>> https://www.postgresql.org/docs/current/routine-vacuuming.html#AUTOVACUUM
>
>
> Sure, I read it before asking.
>
> Taking the first table in the list as an example:
>
>
>         relname          | n_live_tup | n_dead_tup |   left   | 
> n_mod_since_analyze |  left
> --------------------------+------------+------------+----------+---------------------+--------
> fooooooooooo             |      32781 |     240663 |  -234057 | 
>              513265 | -509937
>
>
> n_dead_tup (not the actual value, but some time after calling 
> pg_stat_reset) is much larger than 20% of n_live_tup 32781, and 
> n_mod_since_analyze is much larger than 10% of it.
>
> Yet it is kept unvacuumed and unanalyzed for a long time.
>
> autovacuum_(vacuum|analyze)_threshold is 50.
>
> What am I missing?
>

What are your autovacuum_(vacuum|analyze_*scale_factor* values?

-- 
Born in Arizona, moved to Babylonia.
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    On 8/20/23 14:10, Rihad wrote:<br>
    <blockquote type="cite"
      cite="mid:c1d7097c-710a-9513-7831-c765a2b622bf@gmail.com">
      <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
      <div class="moz-cite-prefix">On 8/20/23 20:22, Adrian Klaver
        wrote:<br>
      </div>
      <blockquote type="cite"
        cite="mid:9440ab9c-4ee1-7668-5476-dc28e8086524@aklaver.com">On
        8/18/23 22:35, Rihad wrote: <br>
        <blockquote type="cite">On 8/17/23 13:01, rihad wrote: <br>
          <blockquote type="cite"> <br>
            Hi, all. After calling pg_stat_reset all statistics used by
            autovacuum got zeroed, and started accumulating from
            scratch. Some tables get acted upon properly, some don't. <br>
            <br>
            <br>
          </blockquote>
          Self-replying: yup, it seems there's an arbitrary limit of
          100K of n_live_tup after which autovac/analyze kicks in, or it
          seems so. <br>
        </blockquote>
        <br>
        To know rather then guess read: <br>
        <br>
        <a class="moz-txt-link-freetext"
href="https://www.postgresql.org/docs/current/routine-vacuuming.html#AUTOVACUUM"
          moz-do-not-send="true">https://www.postgresql.org/docs/current/routine-vacuuming.html#AUTOVACUUM</a>
        <br>
      </blockquote>
      <p><br>
      </p>
      <p>Sure, I read it before asking.</p>
      <p>Taking the first table in the list as an example:</p>
      <p><br>
      </p>
      <p><span style="font-family:monospace">        relname          |
          n_live_tup | n_dead_tup |   left   | n_mod_since_analyze |
           left   <br>
--------------------------+------------+------------+----------+---------------------+--------<br>
          fooooooooooo             |      32781 |     240663 |  -234057
          |              513265 | -509937 <br>
        </span></p>
      <p><br>
      </p>
      <p>n_dead_tup (not the actual value, but some time after calling
        pg_stat_reset) is much larger than 20% of n_live_tup 32781, and
        n_mod_since_analyze is much larger than 10% of it.</p>
      <p>Yet it is kept unvacuumed and unanalyzed for a long time.</p>
      <p>autovacuum_(vacuum|analyze)_threshold is 50.<br>
      </p>
      <p>What am I missing?</p>
    </blockquote>
    <br>
    What are your autovacuum_(vacuum|analyze_<b>scale_factor</b> values?<br>
    <br>
    <div class="moz-signature">-- <br>
      Born in Arizona, moved to Babylonia.</div>
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