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List: postgresql-general
Subject: Re: Understanding pg_stat_io.evictions
From: "Daniel Westermann (DWE)" <daniel.westermann () dbi-services ! com>
Date: 2023-07-31 7:57:23
Message-ID: GV0P278MB0419D67F8EA158F25D4D8E29D205A () GV0P278MB0419 ! CHEP278 ! PROD ! OUTLOOK ! COM
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> > postgres=# insert into t select i, md5(i::text), md5(i::text), md5(i::text) from \
> > generate_series(1,1000000) i;
> ..
> > client backend | 207 | normal
> > client backend | 0 | vacuum
> >
> > Shouldn't these evictions show up under context blkwrite? The description in docs \
> > is:
> No, that's not the case because INSERT doesn't execute a bulk
> write. It is is only performed during COPY FROM, and the write side of
> some other comands, such as CREATE AS (and some internal table-copy
> operations.).
Thanks, makes sense.
> > As far as I understand this, a ring buffer is used in this case. Do I miss \
> > something?
> Maybe you're confusiong it with bulk-read cases?
Yes, you're right.
Thank you
Daniel
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<div>>> postgres=# insert into t select i, md5(i::text), md5(i::text), \
md5(i::text) from generate_series(1,1000000) i;<br> </div>
<div class="BodyFragment"><font size="2"><span style="font-size:11pt">
<div class="PlainText elementToProof">>..<br>
>> client backend | 207 | normal<br>
>> client backend | 0 | \
vacuum<br> >> <br>
>> Shouldn't these evictions show up under context blkwrite? The description in \
docs is:<br> <br>
>No, that's not the case because INSERT doesn't execute a bulk<br>
>write. It is is only performed during COPY FROM, and the write side of<br>
>some other comands, such as CREATE AS (and some internal table-copy<br>
>operations.).<br>
</div>
<div class="PlainText elementToProof"><br>
</div>
<div class="PlainText elementToProof">Thanks, makes sense.<br>
</div>
<div class="PlainText elementToProof"><br>
>> As far as I understand this, a ring buffer is used in this case. Do I miss \
something?<br> <br>
>Maybe you're confusiong it with bulk-read cases?<br>
</div>
<div class="PlainText elementToProof"><br>
</div>
<div class="PlainText elementToProof">Yes, you're right.</div>
<div class="PlainText elementToProof"><br>
</div>
<div class="PlainText elementToProof">Thank you</div>
<div class="PlainText elementToProof">Daniel<br>
</div>
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