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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-9870] Rollback should not enforce unique indexes while applying ops</title>
                <link>https://jira.mongodb.org/browse/SERVER-9870</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;p&gt;We recently had an event where our primary server had to step down and after the new election occurred was put into a rollback state. During the rollback mongo encountered a unique index violation while attempting to write to the view_stats collection and promptly crashed.&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;
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				&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;Mon Jun  3 18:50:32 [repl writer worker 2] ERROR: writer worker caught exception: E11000 duplicate key error index: songza.view_stats.$view_1_host_1_pid_1  dup key: { : null, : null, : null } on: { ts: Timestamp 1370285310000|4, h: 1593562783886765644, v: 2, op: &quot;u&quot;, ns: &quot;songza.view_stats&quot;, o2: { _id: ObjectId(&apos;51ace4772a5a3f13accdbe17&apos;) }, o: { $set: { count: 2 }, $set: { sum_ms: 29 }, $set: { sum_square_ms: 565 } } }&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;Mon Jun  3 18:50:32 [repl writer worker 2]   Fatal Assertion 16360&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;0xb07561 0xacc8b3 0x9abaf6 0xadab5d 0xb4d3d9 0x7f845177be9a 0x7f8450a8ecbd &lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
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						&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;/usr/bin/mongod(_ZN5mongo15printStackTraceERSo+0x21) [0xb07561]&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;/usr/bin/mongod(_ZN5mongo13fassertFailedEi+0xa3) [0xacc8b3]&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
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						&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;/usr/bin/mongod(_ZN5mongo7replset14multiSyncApplyERKSt6vectorINS_7BSONObjESaIS2_EEPNS0_8SyncTailE+0x156) [0x9abaf6]&lt;/span&gt;&lt;/pre&gt;
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		&lt;/tr&gt;
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						&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;/usr/bin/mongod(_ZN5mongo10threadpool6Worker4loopEv+0x26d) [0xadab5d]&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;/usr/bin/mongod() [0xb4d3d9]&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;/lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a) [0x7f845177be9a]&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;/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7f8450a8ecbd]&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;Mon Jun  3 18:50:32 [repl writer worker 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;***aborting after fassert() failure&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;Mon Jun  3 18:50:32 Got signal: 6 (Aborted).&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;Mon Jun  3 18:50:32 Backtrace:&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;0xb07561 0x5598c9 0x7f84509d14a0 0x7f84509d1425 0x7f84509d4b8b 0xacc8ee 0x9abaf6 0xadab5d 0xb4d3d9 0x7f845177be9a 0x7f8450a8ecbd &lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
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						&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;/usr/bin/mongod(_ZN5mongo15printStackTraceERSo+0x21) [0xb07561]&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;/usr/bin/mongod(_ZN5mongo10abruptQuitEi+0x399) [0x5598c9]&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;/lib/x86_64-linux-gnu/libc.so.6(+0x364a0) [0x7f84509d14a0]&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;/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x35) [0x7f84509d1425]&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;/lib/x86_64-linux-gnu/libc.so.6(abort+0x17b) [0x7f84509d4b8b]&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;/usr/bin/mongod(_ZN5mongo13fassertFailedEi+0xde) [0xacc8ee]&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;/usr/bin/mongod(_ZN5mongo7replset14multiSyncApplyERKSt6vectorINS_7BSONObjESaIS2_EEPNS0_8SyncTailE+0x156) [0x9abaf6]&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
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						&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;/usr/bin/mongod(_ZN5mongo10threadpool6Worker4loopEv+0x26d) [0xadab5d]&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
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						&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;/usr/bin/mongod() [0xb4d3d9]&lt;/span&gt;&lt;/pre&gt;
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					&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;/lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a) [0x7f845177be9a]&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
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						&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;/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7f8450a8ecbd]&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 brought the machine back up out of the replicaset and was able to verify that there were 4 bad documents that lacked the host, view and pid fields. No other active hosts had these bad documents and it&apos;s technically highly unlikely that any of our code inserted them in the first place. I removed the bad documents and brought the member back into the replicaset, but it crashed again shortly thereafter with the same error. We were only able to resolve the issue by restoring the database from an EBS snapshot and letting it catch up again.&lt;/p&gt;

&lt;p&gt;I&apos;ve attached a log from the primary to this ticket.&lt;/p&gt;</description>
                <environment>Ubuntu Precise 12.04 LTS</environment>
        <key id="78133">SERVER-9870</key>
            <summary>Rollback should not enforce unique indexes while applying ops</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="9">Done</resolution>
                                        <assignee username="backlog-server-repl">Backlog - Replication Team</assignee>
                                    <reporter username="michael@songza.com">Michael Henson</reporter>
                        <labels>
                    </labels>
                <created>Thu, 6 Jun 2013 17:06:14 +0000</created>
                <updated>Tue, 6 Dec 2022 05:20:29 +0000</updated>
                            <resolved>Mon, 21 Dec 2015 21:25:30 +0000</resolved>
                                    <version>2.2.3</version>
                    <version>2.4.4</version>
                    <version>2.5.0</version>
                                    <fixVersion>3.0.0</fixVersion>
                                    <component>Replication</component>
                                        <votes>3</votes>
                                    <watches>8</watches>
                                                                                                                <comments>
                            <comment id="394328" author="n1t0" created="Fri, 2 Aug 2013 09:56:19 +0000"  >&lt;p&gt;We had a similar behavior just after adding an index with &lt;/p&gt;
{ unique: true, dropDups: true }
&lt;p&gt;. The index got created, and just after that, all our secondaries started to crash with errors &quot;E11000 duplicate key error index&quot; and similar stacks. The only way to stop this from happening again was to remove the index and re-sync secondaries from scratch.&lt;/p&gt;

&lt;p&gt;All our instances are running MongoDB 2.4.3&lt;/p&gt;</comment>
                            <comment id="357834" author="scotthernandez" created="Tue, 11 Jun 2013 16:58:25 +0000"  >&lt;p&gt;Yes, this sounds like the exact situation which would cause this kind of issue. We will look through the oplog for some proof, but I think we can reproduce this in the future either way.&lt;/p&gt;

&lt;p&gt;Thanks for the oplog data.&lt;/p&gt;</comment>
                            <comment id="355729" author="michael@songza.com" created="Sat, 8 Jun 2013 02:30:40 +0000"  >&lt;p&gt;Here are the indexes that are currently on that collection:&lt;/p&gt;

&lt;p&gt;[&lt;br/&gt;
	{&lt;br/&gt;
		&quot;v&quot; : 1,&lt;br/&gt;
		&quot;key&quot; : &lt;/p&gt;
{
			&quot;_id&quot; : 1
		}
&lt;p&gt;,&lt;br/&gt;
		&quot;ns&quot; : &quot;songza.view_stats&quot;,&lt;br/&gt;
		&quot;name&quot; : &quot;&lt;em&gt;id&lt;/em&gt;&quot;&lt;br/&gt;
	},&lt;br/&gt;
	{&lt;br/&gt;
		&quot;v&quot; : 1,&lt;br/&gt;
		&quot;key&quot; : &lt;/p&gt;
{
			&quot;view&quot; : 1,
			&quot;host&quot; : 1,
			&quot;pid&quot; : 1
		}
&lt;p&gt;,&lt;br/&gt;
		&quot;unique&quot; : true,&lt;br/&gt;
		&quot;ns&quot; : &quot;songza.view_stats&quot;,&lt;br/&gt;
		&quot;name&quot; : &quot;view_1_host_1_pid_1&quot;,&lt;br/&gt;
		&quot;background&quot; : true&lt;br/&gt;
	}&lt;br/&gt;
]&lt;/p&gt;

&lt;p&gt;This collection acts as a staging ground to store performance information on various routes in our REST api. There are basically two sorts of operations that we perform on the documents in this collection. The first is to perform an upsert on a particular (view, host, pid) which will increment the count, sum_ms, and sum_square_ms fields. This action is triggered by a request being issued against our API for the given route (called view in this case). We don&apos;t actually perform an upsert for every request. Instead, we sample, let&apos;s say 10% of our requests. The second sort of operation occurs once per minute. We aggregate all of the documents for a given view and then delete them all one view at a time.&lt;/p&gt;</comment>
                            <comment id="355483" author="scotthernandez" created="Fri, 7 Jun 2013 18:46:31 +0000"  >&lt;p&gt;Thanks Michael, &lt;/p&gt;

&lt;p&gt;Can you also provide your index definitions for that collection:&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;&amp;gt; use songza&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;&amp;gt; db.view_stats.getIndexes()&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;We believe the problem was a transitive index violation during the rollback because documents were being replaced by the current ones (as existed on the new/current primary) in an order different than happened in the original timeline. We are trying to track down where this might be possible by looking at the oplog as a hint since we can&apos;t really go back in time &lt;img class=&quot;emoticon&quot; src=&quot;https://jira.mongodb.org/images/icons/emoticons/smile.png&quot; height=&quot;16&quot; width=&quot;16&quot; align=&quot;absmiddle&quot; alt=&quot;&quot; border=&quot;0&quot;/&gt;  Once we get the indexes it should be a little more clear. &lt;/p&gt;

&lt;p&gt;Do you think the application/data might have changed documents in an order where looking at two different points in time, in that small windows of time, there were two documents which had the same [&lt;b&gt;view, host, pid&lt;/b&gt;] values (it seems like you have a unique index on the combination of those three fields)?&lt;/p&gt;</comment>
                            <comment id="355407" author="michael@songza.com" created="Fri, 7 Jun 2013 16:42:11 +0000"  >&lt;p&gt;Here are the contents of the oplog on that machine from after 2013-06-03T18:48:00 (the log indicated this was the date to sync back to).&lt;/p&gt;</comment>
                            <comment id="354704" author="scotthernandez" created="Thu, 6 Jun 2013 19:09:12 +0000"  >&lt;p&gt;Would it be possible for you to upload the oplog from that &quot;rollback&quot; host? Really we just need the portion being used to do the rollback.&lt;/p&gt;</comment>
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