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id="docs-internal-guid-fb5b1b9d-ac38-63ff-458c-7584742b2c7e"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">Because
of ongoing issues with data quality in Firefox Health Report
(FHR), we are planning on changing the way data is sent and
stored on the server.</span></p>
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<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">Currently
Firefox and the server try to cooperate in storing only one
record for each browser instance; they do this by creating a new
upload ID on each upload and removing the document from the
prior upload ID. In practice this system is not working:
situations like backups, profile copying, machine imaging, and
other scenarios are causing “orphan” documents in the FHR
dataset, skewing many kinds of statistics that FHR was designed
to collect.</span></p>
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<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">We
are changing this system to upload using a single identifier per
browser instance for all uploads.</span></p>
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<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">The
original varying document ID was developed to improve user
privacy. In reality it doesn’t help: to associate FHR data with
a particular person you would have to get the ID off of their
client, but the client already stores all of the relevant data.
The rotating server ID doesn’t provide any additional privacy
benefit.</span></p>
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<span
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<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">For
a transition period, we are going to add the stable identifier
to the FHR payload: this will allow us to reliably measure the
orphaning problem and give us time to add some additional
error-handling and logging code to the collection servers. After
we’ve verified that the stable ID isn’t causing new problems, we
will switch the client to upload using the stable ID.</span></p>
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<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">In
the case of profile copying and machine imaging, we may end up
in a state where multiple Firefox profiles are uploading data to
the same identifier. This may not be a problem in practice, but
if we do measure this happening, we have a plan to help address
the issue:</span></p>
<br>
<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">On
upload, the server will compare the new data with existing data.
If the data doesn’t match, the server will log the affected
documents and mark the upload ID as inactive. The next time any
client tries to upload to an inactive ID, the server will
instruct the client to generate and switch to a new random ID.</span></p>
<br>
<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">The
client-side bug for the initial stage of this work is bug
968419.</span></p>
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<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span>
<p dir="ltr"
style="line-height:1.15;margin-top:0pt;margin-bottom:0pt;"><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">Please
direct any questions or concerns to the fhr-dev mailing list.</span></p>
<br>
<span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;"></span><span
style="font-size:15px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;">--BDS<br>
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