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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>
    </build-info>


<item>
            <title>[CDRIVER-2063] JSON export prints insignificant digits / noise</title>
                <link>https://jira.mongodb.org/browse/CDRIVER-2063</link>
                <project id="10030" key="CDRIVER">C Driver</project>
                    <description>&lt;p&gt;Since version 1.6 of the C driver, exporting data to JSON leads to unfortunate rounding/printing behavior. For example a simple value:&lt;/p&gt;

&lt;p/&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;&amp;gt; db.test.find()&lt;/span&gt;&lt;/pre&gt;
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					&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;{ &quot;_id&quot; : ObjectId(&quot;58a84a0325b646783be8cf6e&quot;), &quot;x&quot; : 1.8 }&lt;/span&gt;&lt;/pre&gt;
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&lt;p/&gt;

&lt;p&gt;Previously, exporting this data with the C driver would lead to the correct output:&lt;/p&gt;

&lt;p/&gt;
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					&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; mongo(&quot;test&quot;)$export()&lt;/span&gt;&lt;/pre&gt;
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					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;   margin-bottom: 10px;  width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;{ &quot;_id&quot; : { &quot;$oid&quot; : &quot;58a84a0325b646783be8cf6e&quot; }, &quot;x&quot; : 1.8 }&lt;/span&gt;&lt;/pre&gt;
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&lt;p/&gt;

&lt;p&gt;However with the new C driver I get:&lt;/p&gt;

&lt;p/&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;{ &quot;_id&quot; : { &quot;$oid&quot; : &quot;58a84a0325b646783be8cf6e&quot; }, &quot;x&quot; : 1.8000000000000000444 }&lt;/span&gt;&lt;/pre&gt;
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&lt;p/&gt; 

&lt;p&gt;Unfortunately this can be a serious problem for scientific applications where numeric precision is important.&lt;/p&gt;</description>
                <environment></environment>
        <key id="355391">CDRIVER-2063</key>
            <summary>JSON export prints insignificant digits / noise</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="13202">Works as Designed</resolution>
                                        <assignee username="jesse@mongodb.com">A. Jesse Jiryu Davis</assignee>
                                    <reporter username="jeroen.ooms">Jeroen Ooms</reporter>
                        <labels>
                    </labels>
                <created>Sat, 18 Feb 2017 13:29:04 +0000</created>
                <updated>Mon, 29 Jan 2024 12:08:25 +0000</updated>
                            <resolved>Tue, 28 Feb 2017 15:06:36 +0000</resolved>
                                                                    <component>json</component>
                                        <votes>0</votes>
                                    <watches>3</watches>
                                                                                                                <comments>
                            <comment id="1511228" author="jesse" created="Tue, 28 Feb 2017 15:06:36 +0000"  >&lt;p&gt;Closing based on Luke&apos;s comment.&lt;/p&gt;</comment>
                            <comment id="1505298" author="luke.lovett" created="Tue, 21 Feb 2017 18:50:58 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=jesse&quot; class=&quot;user-hover&quot; rel=&quot;jesse&quot;&gt;jesse&lt;/a&gt;, I think that &lt;tt&gt;%.20g&lt;/tt&gt; seems reasonable. Even using &lt;tt&gt;%g&lt;/tt&gt; would not solve the problem Jeroen sees, since more precise numbers would be truncated. It seems a better policy to emit more digits than necessary.&lt;/p&gt;

&lt;p&gt;FWIW, the Python interpreter does something complicated with &lt;tt&gt;repr(some_float)&lt;/tt&gt; called on a floating point, where it prints the fewest possible digits &lt;tt&gt;d_0, d_1, ..., d_n&lt;/tt&gt; such that &lt;tt&gt;float(d_0, d_1, ..., d_n) == float(some_float)&lt;/tt&gt;. This is very convenient, but I don&apos;t think it&apos;s necessary for everyone to implement. See &lt;a href=&quot;https://bugs.python.org/issue1580&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;https://bugs.python.org/issue1580&lt;/a&gt; if interested.&lt;/p&gt;
</comment>
                            <comment id="1504502" author="jesse" created="Mon, 20 Feb 2017 20:14:33 +0000"  >&lt;p&gt;Hey Jeroen, I asked @llvt to help answer, since he&apos;s the author of our Extended JSON Spec and understands format specifiers better than me. What I want to say is, we&apos;ve somewhat standardized on printf (&quot;%.20g&quot;) as our definitive string-encoding of doubles, as you can see in this test:&lt;/p&gt;

&lt;p&gt;&lt;a href=&quot;https://github.com/mongodb/specifications/blob/deff67d64b61861fee9e02dc5f38f574dc8b0513/source/bson-corpus/tests/double.json#L17-L17&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;https://github.com/mongodb/specifications/blob/deff67d64b61861fee9e02dc5f38f574dc8b0513/source/bson-corpus/tests/double.json#L17-L17&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;I changed the format string in libbson 1.6 from &quot;%g&quot; to &quot;%.20g&quot;, which resulted in the change you see, but it matches the standard tests that all MongoDB drivers must pass so I don&apos;t think we should revert it.&lt;/p&gt;</comment>
                            <comment id="1503177" author="jeroen.ooms" created="Sat, 18 Feb 2017 13:32:38 +0000"  >&lt;p&gt;It looks like `mongoexport` does not suffer from this problem; only the C driver does.&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;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; mongoexport --db test --collection test&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;2017-02-18T14:33:18.500+0100	connected to: localhost&lt;/span&gt;&lt;/pre&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;{&quot;_id&quot;:{&quot;$oid&quot;:&quot;58a84a0325b646783be8cf6e&quot;},&quot;x&quot;:1.8}&lt;/span&gt;&lt;/pre&gt;
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&lt;/div&gt;
&lt;p/&gt;</comment>
                    </comments>
                <issuelinks>
                            <issuelinktype id="10012">
                    <name>Related</name>
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            <issuekey id="1317628">CDRIVER-3626</issuekey>
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