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help / color / mirror / Atom feedFrom: Jim Nasby <[email protected]>
To: Andres Freund <[email protected]>
To: Melanie Plageman <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Heikki Linnakangas <[email protected]>
Cc: Thomas Munro <[email protected]>
Cc: Nazir Bilal Yavuz <[email protected]>
Subject: Re: Confine vacuum skip logic to lazy_scan_skip
Date: Thu, 4 Jan 2024 17:25:22 -0600
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAAKRu_Yf3gvXGcCnqqfoq0Q8LX8UM-e-qbm_B1LeZh60f8WhWA@mail.gmail.com>
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<div class="moz-cite-prefix">On 1/4/24 2:23 PM, Andres Freund wrote:<br>
</div>
<blockquote type="cite"
cite="mid:[email protected]">
<pre><pre class="moz-quote-pre" wrap="">On 2024-01-02 12:36:18 -0500, Melanie Plageman wrote:
</pre><blockquote type="cite" style="color: #007cff;"><pre
class="moz-quote-pre" wrap="">Subject: [PATCH v2 1/6] lazy_scan_skip remove unnecessary local var rel_pages
Subject: [PATCH v2 2/6] lazy_scan_skip remove unneeded local var
nskippable_blocks
</pre></blockquote><pre class="moz-quote-pre" wrap="">I think these may lead to worse code - the compiler has to reload
vacrel->rel_pages/next_unskippable_block for every loop iteration, because it
can't guarantee that they're not changed within one of the external functions
called in the loop body.</pre></pre>
</blockquote>
<p>Admittedly I'm not up to speed on recent vacuum changes, but I
have to wonder if the concept of skipping should go away in the
context of vector IO? Instead of thinking about "we can skip this
range of blocks", why not maintain a list of "here's the next X
number of blocks that we need to vacuum"?<br>
</p>
<pre class="moz-signature" cols="72">--
Jim Nasby, Data Architect, Austin TX</pre>
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Subject: Re: Confine vacuum skip logic to lazy_scan_skip
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