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<channel>
    <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>
    </build-info>


<item>
            <title>[SERVER-32150] Only increment scanAndOrder once per logical operation</title>
                <link>https://jira.mongodb.org/browse/SERVER-32150</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;p&gt;We will increment the scanAndOrder metric once per operation, which includes getMore operations. This makes for the following strange behaviors:&lt;/p&gt;
&lt;ul&gt;
	&lt;li&gt;The number of times this metric is incremented depends on the batchSize used. A smaller batch size will mean more getMores, and the metric will be incremented once per getMore.&lt;/li&gt;
	&lt;li&gt;In a sharded aggregation which performs a blocking sort, this metric will be incremented &lt;em&gt;at least&lt;/em&gt; twice, once for the &apos;cursor establishment&apos; portion of the aggregate, sent with batchSize: 0, and once for the actual computation of the first batch, which happens in a getMore.&lt;/li&gt;
&lt;/ul&gt;


&lt;h3&gt;&lt;a name=&quot;OriginalDescription&quot;&gt;&lt;/a&gt;Original Description&lt;/h3&gt;

&lt;p&gt;Currently each operation that reports to have a sort stage &lt;a href=&quot;https://github.com/mongodb/mongo/blob/r3.6.0-rc0/src/mongo/db/curop_metrics.cpp#L79&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;will increment the global serverStatus counter &quot;metrics.operation.scanAndOrder&quot;&lt;/a&gt;. When an aggregation is issued against a sharded cluster, this number can be incremented twice, once for the shards half of the pipeline, and once for the merging half (see also &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-32014&quot; title=&quot;scanAndOrder serverStatus metric should not be incremented for $sort stages that are merging pre-sorted results&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-32014&quot;&gt;&lt;del&gt;SERVER-32014&lt;/del&gt;&lt;/a&gt;). &lt;/p&gt;

&lt;p&gt;This arguably makes sense, since from the &lt;tt&gt;mongod&lt;/tt&gt;&apos;s perspective there are two operations performing a blocking sort. On the other hand there was only one operation that performed a blocking sort from the client&apos;s perspective. For one last perspective, we did technically scan and order documents twice for that operation. If this metric is tracking the number of times the server performed a blocking sort, then we should increment this once per blocking &lt;tt&gt;$sort&lt;/tt&gt; stage, not once per operation.&lt;/p&gt;</description>
                <environment></environment>
        <key id="467198">SERVER-32150</key>
            <summary>Only increment scanAndOrder once per logical operation</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="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-execution">Backlog - Query Execution</assignee>
                                    <reporter username="charlie.swanson@mongodb.com">Charlie Swanson</reporter>
                        <labels>
                    </labels>
                <created>Fri, 1 Dec 2017 22:29:59 +0000</created>
                <updated>Tue, 6 Dec 2022 03:45:27 +0000</updated>
                                            <version>3.4.0</version>
                    <version>3.6.0</version>
                                                    <component>Aggregation Framework</component>
                    <component>Diagnostics</component>
                                        <votes>0</votes>
                                    <watches>11</watches>
                                                                                                                <comments>
                            <comment id="1753272" author="charlie.swanson" created="Fri, 15 Dec 2017 18:22:11 +0000"  >&lt;p&gt;Oh - yea I found an easier way to test my above hypothesis, if I play with the batch size I can force more getMores to happen. Looks like this is just being incremented on each getMore, but a max of once per operation. Note this is tested on 3.6, which for operations like the following without allowDiskUse will perform the merge on mongos, so there is no merging operation happening on either shard.&lt;/p&gt;
&lt;p/&gt;
&lt;div id=&quot;syntaxplugin&quot; class=&quot;syntaxplugin&quot; style=&quot;border: 1px dashed #bbb; border-radius: 5px !important; overflow: auto; max-height: 30em;&quot;&gt;
&lt;table cellspacing=&quot;0&quot; cellpadding=&quot;0&quot; border=&quot;0&quot; width=&quot;100%&quot; style=&quot;font-size: 1em; line-height: 1.4em !important; font-weight: normal; font-style: normal; color: black;&quot;&gt;
		&lt;tbody &gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;  margin-top: 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;// Before any operation:&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;mongo localhost:20000 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0000)&quot;)&apos;; mongo localhost:20001 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0001)&quot;)&apos;&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 8 (shard0000)&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 8 (shard0001)&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;// Use a smaller batch size to force multiple batches.&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;db.sharded.aggregate([{$match: {A: {$in: [343, 467, 64903, 45698]}}}, {$sort: {C: 1}}], {cursor: {batchSize: 2}})&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 1324, &quot;A&quot; : 343, &quot;B&quot; : 3253, &quot;C&quot; : 3134, &quot;D&quot; : 4143 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 459, &quot;A&quot; : 64903, &quot;B&quot; : 6049, &quot;C&quot; : 4096, &quot;D&quot; : 1345 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 698, &quot;A&quot; : 45698, &quot;B&quot; : 589, &quot;C&quot; : 4981, &quot;D&quot; : 20956 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 1212, &quot;A&quot; : 467, &quot;B&quot; : 305, &quot;C&quot; : 6908243, &quot;D&quot; : 394058 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;...&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;mongo localhost:20000 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0000)&quot;)&apos;; mongo localhost:20001 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0001)&quot;)&apos;&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 11 (shard0000)  // Up by 3, this shard must have had more than one batch&apos;s worth of documents (&amp;gt;2)&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   margin-bottom: 10px;  width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 10 (shard0001)  // This went up by 2, presumably because the initial aggregate simply opened a cursor, and the getMore returned the 1 matching document.&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
			&lt;/tbody&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;p/&gt;

&lt;p&gt;Compared to without specifying batch size:&lt;/p&gt;
&lt;p/&gt;
&lt;div id=&quot;syntaxplugin&quot; class=&quot;syntaxplugin&quot; style=&quot;border: 1px dashed #bbb; border-radius: 5px !important; overflow: auto; max-height: 30em;&quot;&gt;
&lt;table cellspacing=&quot;0&quot; cellpadding=&quot;0&quot; border=&quot;0&quot; width=&quot;100%&quot; style=&quot;font-size: 1em; line-height: 1.4em !important; font-weight: normal; font-style: normal; color: black;&quot;&gt;
		&lt;tbody &gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;  margin-top: 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;// Before operation:&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;mongo localhost:20000 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0000)&quot;)&apos;; mongo localhost:20001 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0001)&quot;)&apos;&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 11 (shard0000)&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 10 (shard0001)&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;// No batch size, everything should fit in first batch.&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;mongos&amp;gt; db.sharded.aggregate([{$match: {A: {$in: [343, 467, 64903, 45698]}}}, {$sort: {C: 1}}])&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 1324, &quot;A&quot; : 343, &quot;B&quot; : 3253, &quot;C&quot; : 3134, &quot;D&quot; : 4143 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 459, &quot;A&quot; : 64903, &quot;B&quot; : 6049, &quot;C&quot; : 4096, &quot;D&quot; : 1345 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 698, &quot;A&quot; : 45698, &quot;B&quot; : 589, &quot;C&quot; : 4981, &quot;D&quot; : 20956 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : 1212, &quot;A&quot; : 467, &quot;B&quot; : 305, &quot;C&quot; : 6908243, &quot;D&quot; : 394058 }&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;...&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;mongo localhost:20000 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0000)&quot;)&apos;; mongo localhost:20001 --quiet --eval &apos;print(&quot;scanAndOrder = &quot; + db.serverStatus().metrics.operation.scanAndOrder + &quot; (shard0001)&quot;)&apos;&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 13 (shard0000)  // Each increments by 2.&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   margin-bottom: 10px;  width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;scanAndOrder = 12 (shard0001)&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
			&lt;/tbody&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;p/&gt;

&lt;p&gt;I wouldn&apos;t really consider this conclusive evidence, but combined with my above comment and the priority of &apos;Backlog&apos;, I&apos;m going to stop there. We can reconsider when this ticket is scheduled in the future.&lt;/p&gt;</comment>
                            <comment id="1753054" author="charlie.swanson" created="Fri, 15 Dec 2017 15:26:29 +0000"  >&lt;p&gt;So Akira&apos;s reproduction script definitely is accurate, it looks like we&apos;re incrementing it twice for the aggregation in that example. I can&apos;t figure out why though. It looks like the only place we ever touch the &lt;a href=&quot;https://github.com/mongodb/mongo/blob/661bb326d8a02dfa202b003d1766a939e264e2bd/src/mongo/db/curop_metrics.cpp#L53&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;&lt;tt&gt;scanAndOrderCounter&lt;/tt&gt;&lt;/a&gt; is in &lt;a href=&quot;https://github.com/mongodb/mongo/blob/661bb326d8a02dfa202b003d1766a939e264e2bd/src/mongo/db/curop_metrics.cpp#L79&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;&lt;tt&gt;recordCurOpMetrics()&lt;/tt&gt;&lt;/a&gt;, and that will only do it one time if the operation reports to have a sort stage at all, we don&apos;t ask &lt;em&gt;how many&lt;/em&gt; sorts were performed by the operation (maybe we should?). In any case, it looks like we&apos;re somehow calling &lt;tt&gt;recordCurOpMetrics()&lt;/tt&gt; multiple times, which is strange because it looks like the only callers of that are from within write commands and &lt;a href=&quot;https://github.com/mongodb/mongo/blob/661bb326d8a02dfa202b003d1766a939e264e2bd/src/mongo/db/service_entry_point_mongod.cpp#L1223&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;right before we return the response from &lt;tt&gt;ServiceEntryPointMongod::handleRequest()&lt;/tt&gt;&lt;/a&gt;. I&apos;m investigating how and why this is called twice, but I&apos;m gonna have to dig a little bit and set up a debug build with a breakpoint. Will post back if I find anything. My initial hypothesis is that it&apos;s being incremented once on the cursor establishment, and again on the getMore.&lt;/p&gt;</comment>
                            <comment id="1741756" author="asya" created="Mon, 4 Dec 2017 17:59:21 +0000"  >&lt;p&gt;From user POV, it seems like most important is to not ever increment when sort is satisfied by an index, or is a simple merge.&lt;/p&gt;

&lt;p&gt;Second in importance is not over-counting actual in-memory sorts that should be counted.&lt;/p&gt;</comment>
                            <comment id="1740609" author="charlie.swanson" created="Fri, 1 Dec 2017 22:32:41 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=david.storch&quot; class=&quot;user-hover&quot; rel=&quot;david.storch&quot;&gt;david.storch&lt;/a&gt; I put this in &quot;Needs Triage&quot; so that we can discuss what we believe the correct answer to be. We discussed earlier that the number of times this counter increments is not as important as whether it increments at all, so we could also just move this to the backlog and re-visit later.&lt;/p&gt;</comment>
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