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    <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>[DOCS-16394] Investigate changes in SERVER-81133: Speedup logic to persist routing table cache</title>
                <link>https://jira.mongodb.org/browse/DOCS-16394</link>
                <project id="10380" key="DOCS">Documentation</project>
                    <description>    &lt;div class=&quot;panel&quot; style=&quot;background-color: #c2d2c2;border-width: 1px;&quot;&gt;&lt;div class=&quot;panelHeader&quot; style=&quot;border-bottom-width: 1px;background-color: #239eb0;&quot;&gt;&lt;b&gt;Original Downstream Change Summary&lt;/b&gt;&lt;/div&gt;&lt;/div&gt;
&lt;p&gt;    Introduced a new parameter `persistedChunkCacheUpdateMaxBatchSize` on mongod to control the maximum batch size used for updating persisted chunk cache on shards.&lt;/p&gt;

&lt;p&gt;The parameter is defaulted to 1000 and can be changed both at runtime and startup.&lt;/p&gt;
&lt;h2&gt;&lt;a name=&quot;DescriptionofLinkedTicket&quot;&gt;&lt;/a&gt;Description of Linked Ticket&lt;/h2&gt;
&lt;p&gt;    Each shard maintain a persisted version of the collection routing table cache in &lt;tt&gt;config.cache.chunks.&amp;lt;nss&amp;gt;&lt;/tt&gt;. The function used to update this collection is &lt;a href=&quot;https://github.com/mongodb/mongo/blob/669f87e05810e70c9586a5ff46d44aeb550992ad/src/mongo/db/s/shard_metadata_util.cpp#L361&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;updateShardChunks&lt;/a&gt; that is performing sequentially a &lt;a href=&quot;https://github.com/mongodb/mongo/blob/669f87e05810e70c9586a5ff46d44aeb550992ad/src/mongo/db/s/shard_metadata_util.cpp#L406-L418&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;delete operation&lt;/a&gt; followed by an &lt;a href=&quot;https://github.com/mongodb/mongo/blob/669f87e05810e70c9586a5ff46d44aeb550992ad/src/mongo/db/s/shard_metadata_util.cpp#L420-L428&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;insert operation&lt;/a&gt; for every new chunk.&lt;/p&gt;

&lt;p&gt;When the number of new chunks to persist is high, this logic could become extremely slow. For instance, with a routing table of 10 millions chunks, it could take up to 45 min to persist the entire routing table.&lt;/p&gt;

&lt;p&gt;This is problematic because until all the updated chunks get persisted, they will slow down considerably all the concurrent incremental routing table refreshes. For instance, an incremental refresh for a routing table of 10 millions chunks usually takes on the order of 10 milliseconds, but if the routing table needs still to be persisted to disk this incremental refresh can take up to ~5 secs.&lt;/p&gt;

&lt;p&gt;The goal of this ticket is to speedup the logic that persist new chunks in &lt;tt&gt;config.cache.chunks.&amp;lt;nss&amp;gt;&lt;/tt&gt;. One potential solution could be to perform a batch of deletions followed by a batch of insertion.&lt;/p&gt;
</description>
                <environment></environment>
        <key id="2447691">DOCS-16394</key>
            <summary>Investigate changes in SERVER-81133: Speedup logic to persist routing table cache</summary>
                <type id="3" iconUrl="https://jira.mongodb.org/secure/viewavatar?size=xsmall&amp;avatarId=14718&amp;avatarType=issuetype">Task</type>
                                            <priority id="4" iconUrl="https://jira.mongodb.org/images/icons/priorities/minor.svg">Minor - P4</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="jeffrey.allen@mongodb.com">Jeffrey Allen</assignee>
                                    <reporter username="backlog-server-pm">Backlog - Core Eng Program Management Team</reporter>
                        <labels>
                    </labels>
                <created>Thu, 21 Sep 2023 07:02:23 +0000</created>
                <updated>Mon, 5 Feb 2024 16:21:39 +0000</updated>
                            <resolved>Thu, 16 Nov 2023 21:38:13 +0000</resolved>
                                                    <fixVersion>7.2.0-rc0</fixVersion>
                    <fixVersion>7.1.1</fixVersion>
                    <fixVersion>7.0.4</fixVersion>
                    <fixVersion>6.0.13</fixVersion>
                    <fixVersion>5.0.25</fixVersion>
                    <fixVersion>Server_Docs_[20240205]</fixVersion>
                                    <component>manual</component>
                    <component>Server</component>
                        <due></due>
                            <votes>0</votes>
                                    <watches>1</watches>
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                                        <issuelink>
            <issuekey id="2493463">DOCS-16483</issuekey>
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            <issuelink>
            <issuekey id="2529174">DOCS-16555</issuekey>
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            <issuelink>
            <issuekey id="2545466">DOCS-16586</issuekey>
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