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        <build-number>970001</build-number>
        <build-date>13-04-2023</build-date>
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<item>
            <title>[SERVER-56520] Time-series inserts spent a lot of time in wt_calc_modify but don&apos;t generate deltas</title>
                <link>https://jira.mongodb.org/browse/SERVER-56520</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;p&gt;We spend 25% of time on attempting to compute WT_MODIFY deltas, but never succeed to the limit of 16 changes. We should either support deltas with more than 16 changes, or find a way to avoid useless calculations.&lt;/p&gt;

&lt;p&gt;Probably it is best to directly change the &lt;tt&gt;doc_diff&lt;/tt&gt; updates into deltas.&lt;/p&gt;</description>
                <environment></environment>
        <key id="1697758">SERVER-56520</key>
            <summary>Time-series inserts spent a lot of time in wt_calc_modify but don&apos;t generate deltas</summary>
                <type id="1" iconUrl="https://jira.mongodb.org/secure/viewavatar?size=xsmall&amp;avatarId=14703&amp;avatarType=issuetype">Bug</type>
                                            <priority id="3" iconUrl="https://jira.mongodb.org/images/icons/priorities/major.svg">Major - P3</priority>
                        <status id="6" iconUrl="https://jira.mongodb.org/images/icons/statuses/closed.png" description="The issue is considered finished, the resolution is correct. Issues which are closed can be reopened.">Closed</status>
                    <statusCategory id="3" key="done" colorName="success"/>
                                    <resolution id="13201">Fixed</resolution>
                                        <assignee username="yuhong.zhang@mongodb.com">Yuhong Zhang</assignee>
                                    <reporter username="geert.bosch@mongodb.com">Geert Bosch</reporter>
                        <labels>
                    </labels>
                <created>Fri, 30 Apr 2021 17:27:55 +0000</created>
                <updated>Sun, 29 Oct 2023 21:54:13 +0000</updated>
                            <resolved>Thu, 10 Jun 2021 03:46:45 +0000</resolved>
                                                    <fixVersion>5.0.0-rc2</fixVersion>
                    <fixVersion>5.1.0-rc0</fixVersion>
                                                        <votes>0</votes>
                                    <watches>6</watches>
                                                                                                                <comments>
                            <comment id="4108347" author="JIRAUSER1259052" created="Wed, 6 Oct 2021 19:04:28 +0000"  >&lt;p&gt;Updating the fixversion since branching activities occurred yesterday. This ticket will be in rc0 when it&#8217;s been triggered. For more active release information, please keep an eye on #server-release. Thank you!&lt;/p&gt;</comment>
                            <comment id="3871744" author="xgen-internal-githook" created="Thu, 10 Jun 2021 19:54:23 +0000"  >&lt;p&gt;Author:&lt;/p&gt;
{&apos;name&apos;: &apos;Yuhong Zhang&apos;, &apos;email&apos;: &apos;danielzhangyh@gmail.com&apos;, &apos;username&apos;: &apos;YuhongZhang98&apos;}
&lt;p&gt;Message: &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-56520&quot; title=&quot;Time-series inserts spent a lot of time in wt_calc_modify but don&amp;#39;t generate deltas&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-56520&quot;&gt;&lt;del&gt;SERVER-56520&lt;/del&gt;&lt;/a&gt; Time-series inserts spent a lot of time in wt_calc_modify but don&apos;t generate deltas&lt;/p&gt;

&lt;p&gt;(cherry picked from commit f3e5e05277309a8394a33aef9303dfb7ff4c0a4a)&lt;br/&gt;
Branch: v5.0&lt;br/&gt;
&lt;a href=&quot;https://github.com/mongodb/mongo/commit/b2ab180f9556370a2a9ecbf77b7041415cf7fb9c&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;https://github.com/mongodb/mongo/commit/b2ab180f9556370a2a9ecbf77b7041415cf7fb9c&lt;/a&gt;&lt;/p&gt;</comment>
                            <comment id="3869184" author="JIRAUSER1253424" created="Wed, 9 Jun 2021 17:52:14 +0000"  >&lt;p&gt;We are resolving the ticket by skipping the &quot;wiredtiger_calc_modify()&quot; for time-series updates now. We experimented with the original idea which converts the diff in BSON format to &quot;WT_MODIFY&quot; directly, but the assumption that updating with deltas in wiredtiger storage engine is more efficient is not completely true. The implementation in wiredtiger makes it not ideal to integrate the approach for now. So we are keeping the logic in &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-57101&quot; title=&quot;Prove generating DamageVector from docDiff in unittest&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-57101&quot;&gt;&lt;del&gt;SERVER-57101&lt;/del&gt;&lt;/a&gt;, &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-57159&quot; title=&quot;Generate DamageVector from docDiff with subdocuments in unittest&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-57159&quot;&gt;&lt;del&gt;SERVER-57159&lt;/del&gt;&lt;/a&gt;&#160;and &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-57504&quot; title=&quot;Minimize the number of damages created for an internal time-series bucket collection update&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-57504&quot;&gt;&lt;del&gt;SERVER-57504&lt;/del&gt;&lt;/a&gt; with unit tests in the codebase.&lt;/p&gt;

&lt;p&gt;The next step will be removing the special handling in this ticket after implementing a more general heuristic in &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-57482&quot; title=&quot;Adaptively call wiredtiger_calc_modify&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-57482&quot;&gt;SERVER-57482&lt;/a&gt;. This work is not scheduled for 5.0 as it will also affect non-timeseries workload.&lt;/p&gt;

&lt;p&gt;Ultimately, after locating the issue in wiredtiger and work with the storage team, we will still want to take advantages of knowing the structure of our data and make update in wiredtiger smarter.&lt;/p&gt;</comment>
                            <comment id="3868820" author="xgen-internal-githook" created="Wed, 9 Jun 2021 15:52:44 +0000"  >&lt;p&gt;Author:&lt;/p&gt;
{&apos;name&apos;: &apos;Yuhong Zhang&apos;, &apos;email&apos;: &apos;danielzhangyh@gmail.com&apos;, &apos;username&apos;: &apos;YuhongZhang98&apos;}
&lt;p&gt;Message: &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-56520&quot; title=&quot;Time-series inserts spent a lot of time in wt_calc_modify but don&amp;#39;t generate deltas&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-56520&quot;&gt;&lt;del&gt;SERVER-56520&lt;/del&gt;&lt;/a&gt; Time-series inserts spent a lot of time in wt_calc_modify but don&apos;t generate deltas&lt;br/&gt;
Branch: master&lt;br/&gt;
&lt;a href=&quot;https://github.com/mongodb/mongo/commit/f3e5e05277309a8394a33aef9303dfb7ff4c0a4a&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;https://github.com/mongodb/mongo/commit/f3e5e05277309a8394a33aef9303dfb7ff4c0a4a&lt;/a&gt;&lt;/p&gt;</comment>
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            <issuekey id="1754522">SERVER-57159</issuekey>
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            <issuekey id="1770868">SERVER-57504</issuekey>
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