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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Hi Pradeep,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">HPE has investigated the use of Cassandra for Monasca and came to the conclusion that it is not a good choice. One of
the problems is that Cassandra is not performant when querying across big data sets with many dimension key-value combinations. As KairosDB is based on Cassandra it suffers from the same problems.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">The excerpt from KariosDB documentation [1]:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">“So if you have a million tag/value combinations, phase 1 will always take a few seconds to complete. Phase 2 could be
fast if you filter by tags so that only a few partitions are read or it could be slow if you have to read the data from all one million partitions.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">How do you know if what you are planning is going to be fast enough? From our experience if you have 10's of thousands
of tag combinations you will be fine. Once you start getting towards a million you will be in for trouble.”<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">The existing code for Cassandra is planned to be removed.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Greetings<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Witek<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">[1] https://github.com/kairosdb/kairosdb/wiki/Query-Performance<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Pradeep Singh [mailto:ps4openstack@gmail.com]
<br>
<b>Sent:</b> Mittwoch, 1. März 2017 06:51<br>
<b>To:</b> Shinya Kawabata <s-kawabata@wx.jp.nec.com><br>
<b>Cc:</b> OpenStack Development Mailing List (not for usage questions) <openstack-dev@lists.openstack.org>; roland.hochmuth@hpe.com<br>
<b>Subject:</b> Re: [openstack-dev] [monasca] cassandra support in Monasca<o:p></o:p></span></p>
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<p class="MsoNormal">Hello,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I have registered a BP[1] for that.<o:p></o:p></p>
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<p class="MsoNormal">Please let me know if you have any concerns.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">[1]<a href="https://blueprints.launchpad.net/monasca/+spec/kairosdb-support">https://blueprints.launchpad.net/monasca/+spec/kairosdb-support</a><o:p></o:p></p>
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<p class="MsoNormal">Thanks,<o:p></o:p></p>
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<p class="MsoNormal">Pradeep Singh<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Feb 24, 2017 at 2:20 PM, Shinya Kawabata <<a href="mailto:s-kawabata@wx.jp.nec.com" target="_blank">s-kawabata@wx.jp.nec.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi Pradeep<br>
<br>
Basic Cassandra support is already implemented.<br>
But there are some performance problems.<br>
These performance problems are difficult to enhance.<br>
So we are planning to switch other DB and will let Cassandra deprecated.<br>
KariosDB is one of candidates and not implemented yet.<br>
KariosDB is build-on Cassandra so you might have problems we had.<br>
<br>
Regards<br>
<span class="hoenzb"><span style="color:#888888">Shinya Kawabata</span></span><o:p></o:p></p>
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> -----Original Message-----<br>
> From: Pradeep Singh [mailto:<a href="mailto:ps4openstack@gmail.com">ps4openstack@gmail.com</a>]<br>
> Sent: Thursday, February 23, 2017 2:39 PM<br>
> To: OpenStack Development Mailing List (not for usage questions)<br>
> <<a href="mailto:openstack-dev@lists.openstack.org">openstack-dev@lists.openstack.org</a>><br>
> Cc: Kawabata Shinya <<a href="mailto:s-kawabata@wx.jp.nec.com">s-kawabata@wx.jp.nec.com</a>>;<br>
> <a href="mailto:santhosh.fernandes@gmail.com">santhosh.fernandes@gmail.com</a><br>
> Subject: [openstack-dev][monasca] cassandra support in Monasca<br>
><br>
> Hello,<br>
><br>
> Could you please suggest status of Cassandra support in Monasca.<br>
> Is there any plan to support kairosdb?<br>
> If it is not implemented then we can take kairosdb support work.<br>
><br>
> Thanks,<br>
> Pradeep Singh<o:p></o:p></p>
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