<div dir="ltr">Point definitely well made. I'm with you now. :)<div><br></div><div>Now this being the case. I can't just swap the location. This is where I would need a rock solid upgrade hook. But I would only need to run it the once. Any suggestions? Or any good examples?</div></div><br><div class="gmail_quote"><div dir="ltr">On Fri, Oct 28, 2016 at 1:54 PM Kyle Fazzari <<a href="mailto:kyle.fazzari@canonical.com">kyle.fazzari@canonical.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br class="gmail_msg"> <br class="gmail_msg"> On 10/27/2016 11:27 PM, Didier Roche wrote:<br class="gmail_msg"> > Le 27/10/2016 à 19:00, Aaron Ogle a écrit :<br class="gmail_msg"> >> On Thu, Oct 27, 2016 at 11:56 AM Kyle Fazzari<br class="gmail_msg"> >> <<a href="mailto:kyle.fazzari@canonical.com" class="gmail_msg" target="_blank">kyle.fazzari@canonical.com</a> <mailto:<a href="mailto:kyle.fazzari@canonical.com" class="gmail_msg" target="_blank">kyle.fazzari@canonical.com</a>>> wrote:<br class="gmail_msg"> >><br class="gmail_msg"> >><br class="gmail_msg"> >> So are you storing this database in $SNAP_COMMON? Because<br class="gmail_msg"> >> $SNAP_DATA would do this for you, no?<br class="gmail_msg"> >><br class="gmail_msg"> >><br class="gmail_msg"> >> Correct we are doing in $SNAP_COMMON. Is $SNAP_DATA using CoW? Or is<br class="gmail_msg"> >> it going to be a full copy. From what I could see it was a full<br class="gmail_msg"> >> copy. This would quickly add up. Not to mention you loose all of our<br class="gmail_msg"> >> messages sent when you roll back.<br class="gmail_msg"> <br class="gmail_msg"> No, you're correct-- it's a full copy. But ...<br class="gmail_msg"> <br class="gmail_msg"> > I would suggest to use $SNAP_DATA. Once we have garbage collection<br class="gmail_msg"> > enabled on snapd, you will have approx. 2 copies at most of your data<br class="gmail_msg"> > (the old version and the current one). I guess this is a reasonable<br class="gmail_msg"> > tradeoff to ensure you can always revert safely.<br class="gmail_msg"> <br class="gmail_msg"> This ^^ . Note that garbage collection is in place today: snapd will<br class="gmail_msg"> begin pruning revisions once you have three of them, i.e. you will have<br class="gmail_msg"> only the three most recent revisions taking up space.<br class="gmail_msg"> <br class="gmail_msg"> > Imagine the case if a new version corrupts your data. You will not have<br class="gmail_msg"> > any way to retrieve them back if you store in $SNAP_COMMON, whichever<br class="gmail_msg"> > downgrade scripts you are writing…<br class="gmail_msg"> ><br class="gmail_msg"> > So, I would argue to try $SNAP_DATA first, and then only revisit to move<br class="gmail_msg"> > to $SNAP_COMMON if you see that doesn't suit you.<br class="gmail_msg"> <br class="gmail_msg"> I second this. Note that the ability to revert is not necessarily<br class="gmail_msg"> something that should be exercised a week after using the new version<br class="gmail_msg"> ("Nah, the other one was prettier. Revert!") simply because of the<br class="gmail_msg"> limitation you pointed out. It's better used with "Uh oh, my web server<br class="gmail_msg"> isn't coming up with this version. Revert!" or "Uh oh, my database<br class="gmail_msg"> migration failed. Revert!"<br class="gmail_msg"> <br class="gmail_msg"> Of course, nothing says it can't be used that way, but then you run into<br class="gmail_msg"> the limitations of the facilities provided by snapd, and you need to<br class="gmail_msg"> start hosting your data in a version-agnostic area (like you're doing).<br class="gmail_msg"> Which has its risks, as Didier pointed out.<br class="gmail_msg"> <br class="gmail_msg"> --<br class="gmail_msg"> Kyle Fazzari (kyrofa)<br class="gmail_msg"> Software Engineer<br class="gmail_msg"> Canonical Ltd.<br class="gmail_msg"> <a href="mailto:kyle@canonical.com" class="gmail_msg" target="_blank">kyle@canonical.com</a><br class="gmail_msg"> <br class="gmail_msg"> --<br class="gmail_msg"> Snapcraft mailing list<br class="gmail_msg"> <a href="mailto:Snapcraft@lists.snapcraft.io" class="gmail_msg" target="_blank">Snapcraft@lists.snapcraft.io</a><br class="gmail_msg"> Modify settings or unsubscribe at: <a href="https://lists.ubuntu.com/mailman/listinfo/snapcraft" rel="noreferrer" class="gmail_msg" target="_blank">https://lists.ubuntu.com/mailman/listinfo/snapcraft</a><br class="gmail_msg"> </blockquote></div><div dir="ltr">-- <br></div><div data-smartmail="gmail_signature"><div dir="ltr"> <div><br></div><div><table border="0" cellspacing="0" cellpadding="0" style="color:rgb(0,0,0);font-family:verdana;font-size:medium"> <tbody> <tr> <td style="padding-right:15px"> <img src="https://cdn-download.rocket.chat/email-signature.png?v=3" style="width: 80px; display: block; margin-left: 10px;"> </td> <td valign="top" style="padding-left:15px;border-left-width:1px;border-left-style:solid;border-left-color:rgb(240,240,240)"> <table width="100%" border="0" cellspacing="0" cellpadding="3" style="border-collapse:collapse;font-size:12px;margin-top:4px"> <tbody> <tr> <td style="padding:3px 0px 10px;margin:0px;font-family:verdana,geneva,sans-serif;font-size:12px;color:rgb(86,97,120)"> <b style="display:block;font-size:12px">Aaron Ogle</b> <span style="color:rgb(153,153,153);font-size:10px;display:block">Core Developer</span> </td> </tr> <tr> <td style="padding:0px 0px 2px;margin:0px"> <p style="margin:0px;padding:0px"><a href="mailto:aaron.ogle@rocket.chat" style="color:rgb(156,160,172);font-size:10px" target="_blank">aaron.ogle@rocket.chat</a></p> </td> </tr> <tr> </tr> <tr> <td style="padding:0px 0px 2px;margin:0px"> <p style="margin:0px;padding:0px"><a href="https://demo.rocket.chat/direct/aaron.ogle" style="color:rgb(156,160,172);font-size:10px" target="_blank">@aaron.ogle</a></p> </td> </tr> <tr> <td style="padding:0px 0px 2px;margin:0px"> <p style="margin:0px;padding:0px"><a href="https://rocket.chat" style="color:rgb(156,160,172);font-size:10px" target="_blank">https://rocket.chat</a></p> </td> </tr> </tbody> </table> </td> </tr> </tbody> </table></div> </div></div>