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Thanks for the input. I'll go ahead with this plan then.
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<div>Greg</div>
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<div>On Dec 20, 2013, at 2:06 AM, Vipul Sabhaya <<a href="mailto:vipuls@gmail.com">vipuls@gmail.com</a>> wrote:</div>
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<div dir="ltr">I am fine with requiring the deployer to update default values, if they don’t make sense for their given deployment. However, not having any value for older/existing instances, when the code requires it is not good. So let’s create a default
datastore of mysql, with a default version, and set that as the datastore for older instances. A deployer can then run trove-manage to update the default record created.</div>
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<div class="gmail_quote">On Thu, Dec 19, 2013 at 6:14 PM, Tim Simpson <span dir="ltr">
<<a href="mailto:tim.simpson@rackspace.com" target="_blank">tim.simpson@rackspace.com</a>></span> wrote:<br>
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<div>I second Rob and Greg- we need to not allow the instance table to have nulls for the datastore version ID. I can't imagine that as Trove grows and evolves, that edge case is something we'll always remember to code and test for, <span style="font-size:10pt">so
let's cauterize things now by no longer allowing it at all.</span></div>
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<div>The fact that the migration scripts can't, to my knowledge, accept parameters for what the dummy datastore name and version should be isn't great, but I think it would be acceptable enough to make the provided default values sensible and ask operators
who don't like it to manually update the database.</div>
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<div><span style="font-size:10pt">- Tim</span></div>
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<div style="direction:ltr"><font face="Tahoma"><b>From:</b> Robert Myers [<a href="mailto:myer0052@gmail.com" target="_blank">myer0052@gmail.com</a>]<br>
<b>Sent:</b> Thursday, December 19, 2013 9:59 AM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Subject:</b> Re: [openstack-dev] [trove] datastore migration issues<br>
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<div dir="ltr">I think that we need to be good citizens and at least add dummy data. Because it is impossible to know who all is using this, the list you have is probably complete. But Trove has been available for quite some time and all these users will not
be listening on this thread. Basically anytime you have a database migration that adds a required field you *have* to alter the existing rows. If we don't we're basically telling everyone who upgrades that we the 'Database as a Service' team don't care about
data integrity in our own product :)
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<div>Robert</div>
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<div class="gmail_quote">On Thu, Dec 19, 2013 at 9:25 AM, Greg Hill <span dir="ltr">
<<a href="mailto:greg.hill@rackspace.com" target="_blank">greg.hill@rackspace.com</a>></span> wrote:<br>
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<div>We did consider doing that, but decided it wasn't really any different from the other options as it required the deployer to know to alter that data. That would require the fewest code changes, though. It was also my understanding that mysql variants
were a possibility as well (percona and mariadb), which is what brought on the objection to just defaulting in code. Also, we can't derive the version being used, so we *could* fill it with a dummy version and assume mysql, but I don't feel like that solves
the problem or the objections to the earlier solutions. And then we also have bogus data in the database.</div>
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<div>Since there's no perfect solution, I'm really just hoping to gather consensus among people who are running existing trove installations and have yet to upgrade to the newer code about what would be easiest for them. My understanding is that list is basically
HP and Rackspace, and maybe Ebay?, but the hope was that bringing the issue up on the list might confirm or refute that assumption and drive the conversation to a suitable workaround for those affected, which hopefully isn't that many organizations at this
point. </div>
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<div>The options are basically:</div>
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<div>1. Put the onus on the deployer to correct existing records in the database.</div>
<div>2. Have the migration script put dummy data in the database which you have to correct.</div>
<div>3. Put the onus on the deployer to fill out values in the config value</div>
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<div>Greg</div>
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<div>On Dec 18, 2013, at 8:46 PM, Robert Myers <<a href="mailto:myer0052@gmail.com" target="_blank">myer0052@gmail.com</a>> wrote:</div>
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<p dir="ltr">There is the database migration for datastores. We should add a function to back fill the existing data with either a dummy data or set it to 'mysql' as that was the only possibility before data stores.</p>
<div class="gmail_quote">On Dec 18, 2013 3:23 PM, "Greg Hill" <<a href="mailto:greg.hill@rackspace.com" target="_blank">greg.hill@rackspace.com</a>> wrote:<br type="attribution">
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<div style="word-wrap:break-word">I've been working on fixing a bug related to migrating existing installations to the new datastore code:
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<div><a href="https://bugs.launchpad.net/trove/+bug/1259642" target="_blank">https://bugs.launchpad.net/trove/+bug/1259642</a></div>
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<div>The basic gist is that existing instances won't have any data in the datastore_version_id field in the database unless we somehow populate that data during migration, and not having that data populated breaks a lot of things (including the ability to list
instances or delete or resize old instances). It's impossible to populate that data in an automatic, generic way, since it's highly vendor-dependent on what database and version they currently support, and there's not enough data in the older schema to populate
the new tables automatically.</div>
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<div>So far, we've come up with some non-optimal solutions:</div>
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<div>1. The first iteration was to assume 'mysql' as the database manager on instances without a datastore set.</div>
<div>2. The next iteration was to make the default value be configurable in trove.conf, but default to 'mysql' if it wasn't set.</div>
<div>3. It was then proposed that we could just use the 'default_datastore' value from the config, which may or may not be set by the operator.</div>
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<div>My problem with any of these approaches beyond the first is that requiring people to populate config values in order to successfully migrate to the newer code is really no different than requiring them to populate the new database tables with appropriate
data and updating the existing instances with the appropriate values. Either way, it's now highly dependent on people deploying the upgrade to know about this change and react accordingly.</div>
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<div>Does anyone have a better solution that we aren't considering? Is this even worth the effort given that trove has so few current deployments that we can just make sure everyone is populating the new tables as part of their upgrade path and not bother
fixing the code to deal with the legacy data?</div>
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<div>Greg</div>
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