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        <build-number>970001</build-number>
        <build-date>13-04-2023</build-date>
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            <title>[SERVER-64219] $last/$first window functions repeat evaluation for every document in a static window</title>
                <link>https://jira.mongodb.org/browse/SERVER-64219</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;p&gt;The executors for &lt;a href=&quot;https://github.com/10gen/mongo/blob/46a82e8cd87b95cf404420916246e7af8b96850b/src/mongo/db/pipeline/window_function/window_function_exec_first_last.h#L65&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;$last/$first do not cache results&lt;/a&gt;, even if the window is static (&lt;span class=&quot;error&quot;&gt;&amp;#91;unbounded, unbounded&amp;#93;&lt;/span&gt;). This means that we will evaluate the same expression against the same document for every document in the window. &lt;/p&gt;

&lt;p&gt;Without partitioning it&apos;s probably not an interesting case, but I could imagine a query such as &quot;give me the last measurement per device&quot; would be impacted by this.&lt;/p&gt;</description>
                <environment></environment>
        <key id="1994824">SERVER-64219</key>
            <summary>$last/$first window functions repeat evaluation for every document in a static window</summary>
                <type id="4" iconUrl="https://jira.mongodb.org/secure/viewavatar?size=xsmall&amp;avatarId=14710&amp;avatarType=issuetype">Improvement</type>
                                            <priority id="3" iconUrl="https://jira.mongodb.org/images/icons/priorities/major.svg">Major - P3</priority>
                        <status id="10038" iconUrl="https://jira.mongodb.org/images/icons/subtask.gif" description="">Backlog</status>
                    <statusCategory id="2" key="new" colorName="default"/>
                                    <resolution id="-1">Unresolved</resolution>
                                        <assignee username="backlog-query-optimization">Backlog - Query Optimization</assignee>
                                    <reporter username="nicholas.zolnierz@mongodb.com">Nicholas Zolnierz</reporter>
                        <labels>
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                <created>Fri, 4 Mar 2022 17:07:30 +0000</created>
                <updated>Tue, 6 Dec 2022 00:27:11 +0000</updated>
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