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    <title>MongoDB Jira</title>
    <link>https://jira.mongodb.org</link>
    <description>This file is an XML representation of an issue</description>
    <language>en-us</language>    <build-info>
        <version>9.7.1</version>
        <build-number>970001</build-number>
        <build-date>13-04-2023</build-date>
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<item>
            <title>[SERVER-61599] Evaluate prefix compression for clustered collections</title>
                <link>https://jira.mongodb.org/browse/SERVER-61599</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;p&gt;We use &lt;a href=&quot;https://github.com/mongodb/mongo/blob/e25f4d744b46a849b9785d233b527407c40dd830/src/mongo/db/storage/wiredtiger/wiredtiger_index.cpp#L171&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;WT prefix compression&lt;/a&gt; for indexes. Evaluate the tradeoff of storage savings and the performance impact of enabling this for clustered collections.&lt;/p&gt;</description>
                <environment></environment>
        <key id="1928641">SERVER-61599</key>
            <summary>Evaluate prefix compression for clustered collections</summary>
                <type id="3" iconUrl="https://jira.mongodb.org/secure/viewavatar?size=xsmall&amp;avatarId=14718&amp;avatarType=issuetype">Task</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="9">Done</resolution>
                                        <assignee username="daniel.gomezferro@mongodb.com">Daniel Gomez Ferro</assignee>
                                    <reporter username="louis.williams@mongodb.com">Louis Williams</reporter>
                        <labels>
                            <label>PM-2311-M2</label>
                    </labels>
                <created>Thu, 18 Nov 2021 17:34:46 +0000</created>
                <updated>Fri, 7 Jan 2022 14:11:19 +0000</updated>
                            <resolved>Fri, 7 Jan 2022 12:33:33 +0000</resolved>
                                                                                        <votes>0</votes>
                                    <watches>3</watches>
                                                                                                                <comments>
                            <comment id="4280185" author="JIRAUSER1263153" created="Fri, 7 Jan 2022 12:33:33 +0000"  >&lt;p&gt;Prefix compression for clustered collections is not universally useful. Opened &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-62421&quot; title=&quot;Enable prefix compression on clustered collections with long key prefixes&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-62421&quot;&gt;SERVER-62421&lt;/a&gt; to enable it in conjunction with other configuration changes so that it only triggers when it&apos;s advantageous.&lt;/p&gt;</comment>
                            <comment id="4280089" author="JIRAUSER1263153" created="Fri, 7 Jan 2022 10:49:37 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=louis.williams&quot; class=&quot;user-hover&quot; rel=&quot;louis.williams&quot;&gt;louis.williams&lt;/a&gt; I couldn&apos;t find that info on the benchmark runs, but I recreated the TSBS datasets manually. The size difference as reported by &lt;tt&gt;db.system.buckets.point_data.stats()&lt;/tt&gt; is small:&lt;/p&gt;

&lt;div class=&quot;panel&quot; style=&quot;border-width: 1px;&quot;&gt;&lt;div class=&quot;panelHeader&quot; style=&quot;border-bottom-width: 1px;&quot;&gt;&lt;b&gt;TSBS&lt;/b&gt;&lt;/div&gt;&lt;div class=&quot;panelContent&quot;&gt;
&lt;p&gt;With compression: 227610624&lt;br/&gt;
Without compression: 228003840&lt;br/&gt;
Difference: 393216 (~400 KB, 0.17% reduction)&lt;/p&gt;
&lt;/div&gt;&lt;/div&gt;

&lt;p&gt;I also had some data for YCSB datasets, in that case the size is &lt;b&gt;larger&lt;/b&gt; with compression enabled, presumably because the shared prefix is small (just 4 bytes).&lt;/p&gt;

&lt;div class=&quot;panel&quot; style=&quot;border-width: 1px;&quot;&gt;&lt;div class=&quot;panelHeader&quot; style=&quot;border-bottom-width: 1px;&quot;&gt;&lt;b&gt;YCSB&lt;/b&gt;&lt;/div&gt;&lt;div class=&quot;panelContent&quot;&gt;
&lt;p&gt;With compression: 75890688&lt;br/&gt;
Without compression: 68009984&lt;br/&gt;
Difference: -7880704 (~7.5 MB, 11.6 % increase)&lt;/p&gt;
&lt;/div&gt;&lt;/div&gt;</comment>
                            <comment id="4273403" author="louis.williams" created="Tue, 4 Jan 2022 10:53:27 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=daniel.gomezferro&quot; class=&quot;user-hover&quot; rel=&quot;daniel.gomezferro&quot;&gt;daniel.gomezferro&lt;/a&gt; do these tests report the storage size? It would be useful information for weighing the time/space tradeoff here.&lt;/p&gt;</comment>
                            <comment id="4268005" author="JIRAUSER1263153" created="Mon, 27 Dec 2021 16:37:38 +0000"  >&lt;p&gt;I ran a perf build with prefix_compression enabled by default for clustered collections (including time series collections): &lt;a href=&quot;https://spruce.mongodb.com/version/61c9a110562343577524cac7/tasks?sorts=STATUS%3AASC%3BBASE_STATUS%3ADESC&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;https://spruce.mongodb.com/version/61c9a110562343577524cac7/tasks?sorts=STATUS%3AASC%3BBASE_STATUS%3ADESC&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;The results for TSBS are a bit worse:&lt;br/&gt;
 &lt;span class=&quot;image-wrap&quot; style=&quot;&quot;&gt;&lt;img src=&quot;https://jira.mongodb.org/secure/attachment/352623/352623_tsbs_query.png&quot; width=&quot;100%&quot; style=&quot;border: 0px solid black&quot; /&gt;&lt;/span&gt; &lt;/p&gt;

&lt;p&gt;Are there other workloads I could try this on? Should we enabled it by default only for clustered collections but not for time series collections?&lt;/p&gt;</comment>
                    </comments>
                <issuelinks>
                            <issuelinktype id="10012">
                    <name>Related</name>
                                                                <inwardlinks description="is related to">
                                        <issuelink>
            <issuekey id="1960013">SERVER-62421</issuekey>
        </issuelink>
                            </inwardlinks>
                                    </issuelinktype>
                    </issuelinks>
                <attachments>
                            <attachment id="352623" name="tsbs_query.png" size="1547901" author="daniel.gomezferro@mongodb.com" created="Mon, 27 Dec 2021 16:36:09 +0000"/>
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